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IW5EDI Simone – Ham-Radio

Understanding propagation numbers

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How To Read Propagation Numbers

The A index [ LOW is GOOD ]

  • 1 to 6 is BEST
  • 7 to 9 is OK
  • 11 or more is BAD

Represents the overall geomagnetic condition of the ionosphere (“Ap” if averaged from the Kp-Index) (an average of the eight 3-hour K-Indices) (‘A’ referring to amplitude) over a given 24 hour period, ranging (linearly) typically from 1-100 but theoretically up to 400.

A lower A-Index generally suggests better propagation on the 10, 12, 15, 17, & 20 Meter Bands; a low & steady Ap-Index generally suggest good propagation on the 30, 40, 60, 80, & 160 Meter Bands.

SFI index [ HIGH is GOOD ]

  • 70 NOT GOOD
  • 80 GOOD
  • 90 BETTER
  • 100+ BEST

The measure of total radio emissions from the sun at 10.7cm (2800 MHz), on a scale of 60 (no sunspots) to 300, generally corresponding to the sunspot level, but being too low in energy to cause ionization, not related to the ionization level of the Ionosphere.

Higher Solar Flux generally suggests better propagation on the 10, 12, 15, 17, & 20 Meter Bands; Solar Flux rarely affects the 30, 40, 60, 80, & 160 Meter Bands.

K index [ LOW is GOOD ]

  • 0 or 1 is BEST
  • 2 is OK
  • 3 or more is BAD
  • 5 is VERY VERY BAD

The overall geomagnetic condition of the ionosphere (“Kp” if averaged over the planet) over the past 3 hours, measured by 13 magnetometers between 46 & 63 degrees of latitude, and ranging quasi-logarithmically from 0-9. Designed to detect solar particle radiation by its magnetic effect. A higher K-index generally means worse HF conditions.

A lower K-Index generally suggests better propagation on the 10, 12, 15, 17, & 20 Meter Bands; a low & steady Kp-Index generally suggest good propagation on the 30, 40, 60, 80, & 160 Meter Bands.

Copyright VR2/KQ6XA and ARRL OES

Push pull 2m amplifier

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Two 4CX1000A’s in grounded-screen push-pull – an amplifier that did not work.


Describing this amplifier may seem a really silly thing to do, as it never worked well. However, someone else might learn from our mistakes, or even perhaps someone can tell us why it did not work.

Background.
A friend Paul G8WYI and I were are a radio junk sale when we were offered a pair  what appeared to be new  Eimac 4CX1000A tubes. Paul bought them, and I set about designing a 2 m  amplifier to use them. The first thing that became apparent was that the correct Eimac SK-800 series bases, with the screen decoupling capacitor, were very expensive. However, a design published in the 1991 ARRL handbook, A Legal-Limit 2-Metre Tetrode Amplifier, pages 31-57 to 31-72,  using a single 4CX1000A had avoided the need for such a base. The authors, K1JX and W1VD, had used a SK-800 series base with a damaged screen decoupling capacitor and grounded the screen for both RF and DC. They claimed that this avoided the need for the decoupling capacitor in the base and instead meant a cathode decoupling capacitor was needed. However, they argued that any reactance in this cathode decoupling capacitor would not make the amplifier unstable, but would act as negative feedback, and increase drive power.

We did not have any base, but I decided making one was not too difficult, having access to a good mechanical workshop at university.  A picture of the SK-800 base appeared in an Eimac publication, so making one seemed easy. In fact, making a base was a lot of work, and with hindsight is not something I would try again, but I did make a pair of bases that grounded the screens.

The data sheet for the 4CX1000A gives the following as typical operating conditions.

Anode voltage             3000 V
Screen voltage             325 V
Grid voltage               -60 V
Cathode voltage              0 V (cathode grounded for DC+RF)
Output power              1630 W
Zero signal anode current  250 mA

We proposed to run like this

Anode voltage              2675 V
Screen  voltage               0 V (screen grounded for DC+RF)
Cathode voltage            -325 V
Grid voltage               -385 V

Note that voltage differences between our proposed design and the recommended ones are the same. We have 385-325=60 V between grid and cathode, 2675+325 = 3000 between anode and cathode etc. We aimed to return the negative of the HT supply to the cathode and not the ground. Hence a 3000 V HT supply was needed, but the +V would be at +2675 V wrt ground and the -V at -325 V wrt ground.

With the DC sorted out, the next step was to design the RF deck. Having had a lot of success with a  well known twin 4X250B amplifier , I decided to base the twin 4CX1000A on this. The grids had two lengths of 6.3 mm (1/4″) pipe, inductively coupled to the input with a loop and a series capacitor. The anode line was in the shape of the letter U. with the tubes at each end of the U and the DC fed into the middle via an RF choke.

Switch on.

The amplifier was switched on and the DC operating conditions seemed okay. The zero signal anode current was close to the 500 mA expected (2 x 250 mA). It could be adjusted to be exactly 250 mA each tube, by taking the grid voltage very negative on one tube at a time to cut it off. It was clear the DC conditions were fine. It was also clear that the amplifier was stable no matter how we neutralised it – something necessary to get 100% right on the W1SL design, otherwise it took off and took the HV fuses with it. Our twin 4CX1000A amplifier was remarkably stable. So far so good !

Application of RF.
When RF was applied, the amplifier did a job of amplifying. In fact, with less than a Watt of drive, several hundred watts came out. However, it was soon apparent was that the amplifier started to draw grid current very early – by a couple of hundred Watts out, the amplifier was drawing grid current. By the time the output was up to 700 W, our grid current meters were at full scale ( 1 mA). I think we eventually ran up to about 800 W out, when the grids were taking a couple of mA each. Clearly the amplifier was non-linear and we were likely to destroy the grids of the tubes if we pushed it any harder.

The grid dissipation rating of the 4CX1000A is 0 W !!!

Despite a lot of effort, a lot of asking around, the amplifier still amplifies, but has never been used in a QSO, as we know it would be non-linear. Why it draws grid current so early is not known to us. We have thought the problem was one of incorrect loading, but have tried various methods of coupling the RF out from the amplifier with no success. No matter what we try, the positive grid current problem will not go away. If you have any comments on this, we would like to hear from you. by email  at drkirkby@ntlworld.com G8WRB is now making a conventional cathode driven YC156/3CX5000A7 amplifier and hopes he has less problems than this design that was unusual to say the least.

PC-programming cable for Kenwood TH-G71A / TH-F6A

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I wanted to make my own cable to program my Kenwood TH-G71A ham radio with a PC, but the owner’s manual simply did not show the pinout needed for the connector plugs. I searched the web but was not able to find this information but I did discover that several other radios used an RS-232-to-logic (0-3.3V) level-shifter and a Full-duplex serial connection (separate RXD / TXD), and found schematics for such interfaces for other radios. I also found a device called the “MAK interface” which claimed to work with the TH-G71A, and the web site listed an interface cable.



With these clues, and after studing the signals coming out of the radio (and lots of debug time …), I finally figured out the plug connections at the radio end.

I was able to use basically the same interface schematic that was claimed to work for the Kenwood PG-4S cable (which is used for the TM-G707 / TM-V7 radios instead of the Kenwood TH-G71).

Refer to http://home.attbi.com/~kc7zru/pg4s.html for the schematic for the PG-4S interface:


The DB-9 connector to the PC is the same, but the connector on radio side is different. (Instead of the 6-pin mini-DIN connector, use the 2.5mm and 3.5mm phono plugs for the TH-G71)



Refer to Drawing at the URL above (Tate Belden’s site), right hand side, starting at the top:

   1. Ignore the tie between pins 4 and 5 of the mini-DIN connector. (There is no such tie on the TH-G71 Cable)
   2. The interface’s “TXD” goes to Ring of 2.5mm plug. (cathode of the diode on the interface)
   3. The interface’s “RxD” goes to the Shield of 3.5mm plug. (collector of NPN on interface)
   4. GND goes to shield of the 2.5mm plug.
   5. The tips of both plugs are No-connect.

Schematic tweaks:
Note: If you have an interface that already works on another radio such as the Kenwood TM-G707 / TM-V7, then you may not need to make these changes!


   1. Change R1 from 150ohm to 1K ohm (this is the resistor feeding the zener diode). I found that 150ohms loaded the line too much and the resulting voltage was too low to power the interface from the Serial port. If you have problems, be sure that the cathode of the Zener is at about 4.9V. I found that the interface worked down to about 3.2V when I just powered this from a variable power supply instead of through the PC serial port (after removing R1 and the zener and just applying voltage at C1)
   2. add a 150K ohm resistor between the Radio TXD to gnd. I did this just to keep the voltage down on the TxD pin because the radio seems to be 3.3V I/O pin (not 5V)
  
Update: Dec 2001: The Kenwood manual for the newer TH-F6 radio shows the pinout for the Plugs (page 46). Through Dec 17, 2001, this web page showed the Ring and Shield of the 3.5mm plug both shorted together, but I have updated the plug pinout to match the Kenwood documentation, and I confirmed that it does work as shown, without the connection to the ring.

I was able to find a 90-degree “elbow” shaped, 2.5mm stereo plug at Radio Shack (p/n 274-298).

Using the interface / software

   1. For TH-G71: Menu 15, TC ON
      Transceiver Control must be enabled, or else you will get a communication timeout error when trying to communicate with the radio after connecting the cable up to your PC. “TC ON” enables the plugs on the side to work as data lines instead of as external mic/speaker.

            Press the “F” button, and then Band, turn the main tuning
            knob to Menu 15 Transceiver Control and turn it ON for
            Programming.  You will need to use a free com port (Com 1 or 2) on the PC.
           

      Note: For the TH-F6 radio, the Kenwood manual states: Access Menu No. 9 and select “PC”

   2. Kenwood Programming software
      Download the PC Programming s/w from Kenwood FTP site ftp://ftp.kenwood.net or web page http://www.kenwood.net/amateur -> downloads -> software -> THG71A
      You should see the files mg71200.exe and readme.txt .
      Install the software and Run mcp-g71.exe. go to file menu, and be sure your com port is set correctly, then turn on radio, and plug in, and do “Radio-> Read”. Try it a few times — I found that it sometimes said something like “Communication timeout” the first time I tried after connecting up the interface.

Debugging problems with the interface

   1. Be sure you have done everything listed under “Use”. If you are really stuck, you can try these checks:
   2. Verify power + side:
         1. With the interface connected to the pc, connect a meter to node 1 (cathode of the Zener) and ground.
         2. In the MCP program, do radio->read (you should see “reading data from radio”) As it is “trying” to read the radio, quickly check the voltage.
         3. The voltage should be about 4-5 Volts. This is needed to power the interface from the serial port. Note: The voltage at the RTS and CTS pins of the DB-9 connector will NEGATIVE when the Com port is inactive (when you are not trying to read or write to the radio with the software). But the voltage will go POSITIVE (about 9V on my PC) when the Com port is active.
            Condition     RTS/CTS Voltage
            Com port idle, not reading/writing radio     about -6 to -12V
            Com port active, reading/writing radio     about +6 to +12V
         4. If you don’t have good power here, something is wrong. (This is why I increased R1 resistance from the original schematic – as the original lower value loaded my serial port down too much due to the diode at node 1).
            You can power the interface externally: Remove the rts/cts connections from the PC and just power node 1 with a battery or external power supply. This was the main problem I had getting my interface working (besides trying to figure out the pinouts of kenwood jacks).
   3. Verify power negative (-) side:
         1. With the interface connected to the pc, connect a meter to node 7 (negative terminal of the Cap C2)
         2. In the MCP program, do radio->read (you should see “reading data from radio” As it is “trying” to read the radio, quickly check the voltage.
         3. The voltage should be negative (more negative than about -5 or -6V) This is needed to generate a negative voltage back to the PC RxD.
   4. If this power is good in the previous steps, but the interface still does not work, recheck the interface to make sure everything is wired up correctly including all ground connections, and the pinouts the serial port DB connector. Check all part values and that the polarity of caps is correct, and that NPN and PNP transistor are wired up the correct way.
   5. If that does not find any problems, I would then test the interface to be sure it does the correct level-shifting and “inversion” of the levels from the PC (RS-232) to lower-voltage for the Radio. This can be a bit tricky and you need some power supplies and clips to do this, with the interface disconnected from the PC and the Radio. Basically, you want to verify the following:
         1. With TXD (out from the radio) = 0V, the RxD to PC should be about 5V
         2. With TXD (out from the radio) = 3-5V, the RxD to PC should be between -5V to -12V.
         3. With TXD (out from the PC) between -5V to -12V, the RxD to the Radio should be “floating” (Q2 off) (and the weak pullup in radio pulls the node to a logic “high” value)
         4. With TXD (out of the PC) > 5V or so, the RxD to Radio should be 0V (Q2 is “on”).
      But the catch is that the interface generates the -12V (or so) by the switching on TXD. So you need to fake it out to be sure you have this voltage (which should be there in step 3c) because you don’t have the interface connected to the PC anymore. Otherwise, you won’t get the negative voltage in step 5B.

Programming the TH-G71
See this page for information used to program and control the TH-G71 through a serial port. Serial Port command protocol is provided. This is useful if you are interested in how Kenwood’s MCP memory control program works, or if you are interested in programming the radio using a PC.

Chris Koza azkoza@yahoo.com
KB7QPK

SWL home made antennas

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Home-made antennas can greatly improve the performance of AM and FM radios, short-wave receivers, and scanners. If you are a talk-radio fan then experiment with the AM band antennas and you will be able to hear shows from all over the country with surprising clarity. Short-wave receivers are always coping with weak signals and they must have a good antenna to perform adequately. Scanners can pick up local police and two-way radio with the little telescoping antenna provided but with good antennas a scanner becomes an amazing ear on the world nearby. No pre-amp, filter or other receiver refinement offers anywhere near the level of performance improvemen t that a well-designed antenna offers. The results can be quite satisfying, leaving no doubt that the project was well worth the effort.

This PDF file contains several SWL antennas

SWL Antennas PDFDownload

An Introduction To Amateur Satellite Ground Station Antennas

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There are many kinds of satellite antennas that will get you on the birds (some better than others) and allow you to have lots of fun. If you are new to amateur satellites, though, all the options may be confusing, or worse, a disincentive to try the birds. It’s really not that bad. I offer below some facts and some opinions about the state of the art today and I hope it helps you try some new things and have some fun. I have arranged the information in a progressive outline, allowing you to visualize a step-by-step methodology, gain some experience, and make incremental improvements each time you try something new.

 

Hearing the Birds:
Often, the first challenge is just to hear the satellites. The easiest thing to try first is an HT with 70 cm capability and a “gain” antenna. HT antennas 500-900 mm long (often collapsible) were very effective for UO-14 and SO-35, but are a little weak for AO-27 and SO-50. If you have a mobile dual-band FM radio, try a ¼ wavelength 2 m antenna on 70 cm. These antennas are 3/4 wavelength at 70 cm and offer considerable gain above 30 degrees elevation (deaf below that).

If you want to hear a little better, try a small 70 cm beam. I have plans here for a little 3-element Handi-Tenna. The very popular Arrow Antenna is a convenient and very effective portable antenna. Cushcraft makes a 3+3 dual-band beam with a built-in duplexer, suitable for both portable or fixed station use. All of these antennas are “linearly polarized.” For a great discussion on linear v. circular polarization, see The Amateur Satellite Handbook, by Martin Davidorff, K2UBC (available from both ARRL and AMSAT). Small quads, quagi’s, and helix’s are also workable at 70 cm, but a little more awkward to handle.

Working The “Easy Sats”:
Of course, “easy” is a relative term. See the AMSAT web site for some general introductory articles. The next step for a home station might be to try a simple, omnidirectional circularly polarized antenna. The most common of these is the M2 eggbeater. You can also build a popular version of this antenna, but I have found them to be ineffective at low elevation passes (most passes are below 45 degrees 90 percent of the time). An improved version of this classic design, the Eggbeater II, will give pretty fair results from horizon to horizon, especially if combined with a preamp. The basic Eggbeater II design is fixed right-hand circularly polarized (RHCP), leaving it susceptible to the “fades” common in satellite downlinks (you will not hear 100 % of the pass), but is still an effective, simple antenna–and MUCH better than the “classic” eggbeater. Other antennas in this class are the turnstile, the quadrifilar helix array (QHA), and the Lindenblad.

The next step up is to buy or build a higher gain antenna and rotate it to match the satellite’s position (azimuth). Gain in the 6-7 dBi range, corresponding to a 60 degree beamwidth, is about the maximum that can be utilized without needing elevation control. Unfortunately, there are no commercially available circularly polarized antennas available in this size/gain range. If you don’t mind building somethng from scratch, I recommend the TPM II antenna as a perfect solution for working all the LEO’s. The TPM II antenna does not require an elevation rotor or even accurate pointing (you can do it manually with no trouble). A crafty and inexpensive automatic azimuth rotor system can be easily constructed using WB4APR’s design. I built my TPM II with coaxial relays to switch the circular polarity, allowing me to optimize both downlink and uplink. I can hear and work ALL the LEOs from horizon to horizon using this simple to build antenna and a manual TV-type rotator: I have literally thousands of contacts and have Worked All Continents, WAS, and VUCC with this antenna..

Working AO-10 (not heard since March 2002):
You can work AO-10 with any of the antennas described above when it is near perigee (less than 10,000 km or so with an omni antenna). To work it further out, though, requires considerably more gain. A typical “OSCAR class” station uses 100 Watts on 70 cm for the uplink into a 40 element antenna (20 x 20) and a 22 element (11 x 11) downlink antenna (with mast-mounted preamp). Both antennas are circularly polarized and usually switchable. The most common models here in the US are KLM, Hy-Gain, and M2, but many people also use large linear antennas (or arrays of linear antennas). These antennas require both azimuth and elevation control, most often from a Yaesu or Kenpro rotator. The narrow beamwidth of these antennas also requires precise pointing, making computer control of the rotator almost mandatory: popular devices include FODTrack, Kansas City Tracker, Uni-Trac, and others. This setup is the standard of excellence in satellite antennas today.

Working AO-40 (not heard since December 2003):
AO-40 operation is pretty attractive: a high-altitude orbit that repeats every 4 days, lots of DX, and lots of interesting and educational technical challenges. Mode U/S was the most popular combination, but L/S was favored by many of the operators. Smaller UHF ground station antennas than those used for AO-10 can be used: many use 70 cm uplink antennas in the 10 dBi range. Most any Yagi-Uda beam in the 4-6 element range will work. For L-band, 23 cm, antennas in the 20 dBi range are required if you only have a 10 W rig. Many L-band ops use amplifiers with 40 or more Watts (for BIG! signals). Many operators are taking a wait-and-see approach to AO-40, but if you want to put something up now, you will probably want to consider a small parabolic dish for S-band, 13 cm, as a starter system. For about $200 you can get a 3′ BBQ dish and a low noise MMDS downconverter modified for 2 m. The microwave bands lend themselves to experimentation, so expect to see lots of new and interesting antenna designs published. Almost all of the future satellites have some plans for mode U/S or L/S.

Article by K5OE originally available a http://members.aol.com/k5oe/new_ant_intro.htm

Kenwood TS-850S Mods

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As posted to the CQ Contest e-mail reflector…

Subject: TS-850 contest mods (long)
Date: 4 Jun 1997
From: David O Hachadorian, K6LL
Organization: cq-contest Mailing List [CQ-Contest]

There was a huge number of requests for the TS-850 mods,
so I’ll just post them here.

Mod for External Keying, While Using the Internal Keyer –by N7EX
Front Panel CW Sidetone Level Adjustment Mod –by N6TR
Separate Receive Antenna Modification #1 –by WA3WJD
Separate Receive Antenna Input Mod #2 –by N6TR
PROJECT #2: The switch box –by N6TR
PC Interface, without using the IF-232 Level Converter –by N6TR
Power Output Control –by the unknown contester
Level Attenuator for DRU-2 playback audio –by K6LL

KENWOOD TS-850:

MODIFICATION FOR EXTERNAL KEYING,
WHILE USING THE INTERNAL KEYER
BY: N7EX (ex-N0DH), Dave Henderson

One of the minor draw backs to the TS-850 as a CW contest machine is the inability to use the internal keyer in conjunction with an external keying circuit such as a personal computer or auxiliary memory keyer. As designed you must manually throw a switch from internal to external keying to switch between one or the other. To make matters even more inconvenient this switch is on the back of the unit and is not readily accessible during normal operation.

Simply said this modification involves running a new keying line from the junction of S1 and D51 on the IF Board. For convenience this additional keying line can be wired to the DSP1 and/or DSP2 RCA phono jacks if you do not use the external DSP unit.

The modification to the unit to resolve this problem takes less than 30 minutes to accomplish and can be done without “permanently” modifying the unit which would detract from its future resale value. If you don’t use the external DSP unit then the two RCA phono jacks marked DSP1 and DSP2 can be used as additional keying input jacks as will be outlined below. If you use the external DSP unit then the modification can still be accomplished by running the external keying line out on a “pigtail.” I highly recommend the purchase of a service manual which will greatly improve your ability to indentify the circuit points involved in the modification. Considering that the radio costs $1500 what’s another $30 to keep from messing it up! By the way compared to the two TS-930’s that I nursed through the 80’s, this radio is a breeze to trouble shoot and repair which I have had to do twice through no fault of Kenwood (long stupid story ~8>).

From here you proceed at your own risk, if you fry the radio DON’T CALL ME. A precision low wattage solder pencil for doing surface mount soldering is recommended, If all you have is a 150 watt Weller solder gun then read no farther your better off taking the unit to an expert rather than “melt” the circuit traces.

I assume no risk for the accuracy or completeness of the enclosed information. All yee who enter here embrace all hope for you may likely have a better contest radio when you are done.

1) Turn the unit upside down with the back of the TS-850 toward you.

2) Remove the bottom cover.

3) In this position the IF board is on your left.

4) Remove all the screws holding the IF board to the chassis.
(put them in a jar or something for safe keeping).

5) Unplug enough of the cabling to allow you to tilt the board up so that you can access the bottom side of the board underneath S1 the “External/Internal” keying switch.

6) On the bottom side of the board directly underneath S1 you will see 6 solder pads arranged in two rows of three pads each.

7) The middle pad on S1 nearest the back of the radio should be GROUND, solder the braid of an approximately 9 inch piece of small audio style shielded cable to this point, being careful to dress the coax so as not to short to other circuitry.

8) The middle pad on S1 in the next row up of three pads is the keying line. Solder the center of the shielded cable to this point.

9) Route the other end of the shielded audio cable through the chassis in the vicinity of the DSP jacks above.

10) Carefully inspect all solder joints for shorts, etc. Replug the wire harnesses unplugged in step 5 above and reassemble the board to housing. Reassemble the bottom cover.

11) Turn the unit over and remove the top cover.

12) Find the DSP input board with the three RCA phono jacks on it at the rear of the unit. The two DSP jacks are on the right when facing the rear of the unit. There are two connectors on this board (a 2pin and a 4pin). Unplug the 4 pin connector. Obtain another 4 pin connector and connect as follows (or directly solder to the underside of the board as follows) If you only need one additional CW jack then ground is pin 2 (closer to center of the radio)connect the braid of your new key line to this pin. The input from the middle RCA phono plug is pin 1 connect the ceneter conductor to this pin. Like wise if you want two additional CW jacks then do as above plus add a short between pins 1 and 3. If you want a small RF choke or some ferrite beads on the center conductor of the audio cable may prevent keying problems in high RF field environments…

14) Close the unit up and switch S1 to INTERNAL keying. You should now be able to key the unit via the internal keyer (Via the standard key input jack) or with an external keyer or computer via the old DSP jacks, without having to switch S1.

TS-850 front panel CW sidetone level adjustment, mod by N6TR.
Refer to NCJ, Vol 22, Issue 2, Page 23.

TS-850 Separate Receive Antenna Modification #1.
This modification was developed by Brian, WA3WJD

Make a short loop of white telfon cable with a male and female BNC connector.

Loop it out of the back of the rig so just enough of the coax sticks out so the BNCs can be joined with a barrel connector.

Locate the little header connector on the filter board in the TS-850 that is on the receiver side of the TS850 antenna relay. Pull that connector loose.

Spend a little time tracking down male and female header connectors that match what Kenwood uses. Install those on the ends of the white teflon coaxes sticking in the back of the radio.

For normal use, just connect the BNCs with a barrel connector and the rig is normal. For Beverage use, connect an extra antenna switch common and ant #1 to the BNC connectors, and put ur Beverages on the other positions.

TS-850 Separate RX antenna input mod #2.
This mod was developed by N6TR.

This is near the top of everyone’s list when they are asked “What things bug you about the TS-850S.” I initially overcame this deficiency by modifying my amplifier so I could connect a different receive antenna to the TR relay. However, I wanted to change things so there wasn’t as much RF getting into the RX antenna due to close proximity to the amplifier’s output. This became a problem when using the same receive antenna on a second radio (you knew two radio contest operating was going to work its way in here somehow).

Ville, OH2MM had provided me with instruction on how he modified his TS-850S to have a separate RX input and this inspired me to try it.
Here are some simple steps to hopefully inspire others:

It took me an unrushed two hours to do all this.

1. Remove the top panel (you don’t need to take off the bottom one).

2. Remove the plate which sits between the fan and the back of the radio. This covers the output filter PC board.

3. Unsolder the connections to the SO-239 output connector.

4. Remove the three cables from the PC board next to the SO-239. This includes two coax and one 3 conductor harness.

5. Remove the two screws holding in the PC board and remove it.

6. Locate the trace that goes from the relay’s normally closed contact. You can use an ohm-meter to find it – probe from the wire that went to the SO-239. You will find a short trace on the back of the board which runs to a chip capacitor. Cut this trace and solder some very small coax to each side of the cut – connect ground to the nearby ground trace.

Make the cables about 4 inches long.

7. Remove the antenna tuner. There are 2 screws in the back and front (you will need a magnetic screw-driver) and one on the side. You will need to carefully unplug two wire harnesses and one coax connector.

8. Drill two holes for phono jacks on the back of the radio. Be careful not to obstruct the screw hole for one of the screws in the back of the antenna tuner. The best place is between the RF output connector and the groundpost. Put them on top of each other and as close to the bump on the back panel as possible. I used a vacuum cleaner while drilling to make sure no metal chips went anywhere.

9. You will find a small hole under the SO-239 where you can feed the two coaxs through. Solder them to the phono jacks and reassemble everything. I put back to back diodes on the RX antennas input, but you may not want to do this. A better thing would be to add a relay to disconnect the RX antenna input when transmitting. I took care of that in project #2.

10. Obviously, you will need a jumper cable to make your receiver work again.

PROJECT #2 – The switch box:

  • 4 position rotary switch
  • DPDT 12 VDC relay
  • 1 K Ohm pot (optional)
  • 12 phono jacks (or you can get by with 9)
  • mini box for above and knobs.
  • Clamp diode for relay coil if not included in relay

This box does two things: disconnects the receive antenna input when transmitting and allows selection of the transmitting antenna or one of three RX antennas when receiving. The pot can be used for RF attenuation if your rig doesn’t have one.

The relay gets controlled by the PTT output from your rig that normally would go to your amplifier. Then one set of the contacts is used to key your amplifier. Don’t forget to put a diode across the coil of your relay if there isn’t one internally. Otherwise, you will have undesired arcing across the contacts of the relay in your radio.

The other set of contacts disconnect the output of the rotary swtich when transmitting. The rotary switch selects either the signal coming from the transmitting antenna (from the TR relay in your rig) or one of three receiving antennas. I use two phono jacks per RX antenna so I can feed them to other boxes for other radios. I also use two jacks for +12 volts so I can jumper power to another box.

You can build up one of these boxes in an hour or two. You can epoxy the relay to the mini box.

If you want the pot there to act as an attenuator, I just hook it up like you would a volume control: one end is ground, the other end goes to the output of the rotary switch and the wiper goes to the output. Use shielded cable as much as possible to avoid stray pickup.

Computer Interface for the TS-850, without using the IF-232 Level Converter.
Mod developed by N6TR, and possibly others, with zener idea added by K6LL.
Note: This interface will work with “TR,” contest logging software by N6TR.

Computer Interface:

                    470 ohms
DB9 PIN 3 (TXD)  ----////------------ TS850 ACC 1 PIN 3 (RXD)
(DB25 PIN 2)                  |
                              |
                              |
                            ----  5 VOLT ZENER DIODE
                              / 
                             /  
                              |        
                              |
DB9 PIN 5 (GND)  ------------------------  TS850 ACC 1 PIN 1 (GND)
(DB25 PIN 7)

DB9 PIN 2 (RXD)  ------------------------  TS850 ACC 1 PIN 2 (TXD)
(DB25 PIN 3)

                                   -----  TS850 ACC 1 PIN 4 (CTS)
                                   |
                                   |
                                   |
                                   -----  TS850 ACC 1 PIN 5 (RTS)

TS-850 Power Output Control
VR7 on the RF Board (bottom side of radio). 125 watts or so on cw is safe. Do not exceed
100 watts on SSB, since distortion will broaden the transmitted signal.

TS-850 Level Attenuator for DRU-2 playback audio. Mod by K6LL.

1. Remove the little hatch on the top of the radio.
2. With the front of the radio facing you, find connector CN505. It is a five pin connector near the filter DIP switches. The white wire on the leftmost terminal carries the DRU audio output.
3. Cut the white wire and insert a 100K ohm micromini pot, shunted with a 220 pf capacitor. Adjust the pot until DRU playback level matches live microphone level.

Dave Hachadorian, K6LL

The CobWebb Antenna

Posted in HF Antennas Leave a comment

he G3TPW Cobwebb antenna covers five bands, 14 – 28 mhz, including the WARC bands. It is made by SRW Commuications Ltd (Steve Webb), Astrid House, Swinton, Malton, N. Yorkshire YO17 0SY (tel: 01653 697513).

It is strongly made using fibre glass rods and comes pretuned, but is easily adjusted to one’s own frequency of preferrence if required.

It consists of five nested dipole balun fed and mounted horizontally. Rotation is not required. Fed with 50 ohm coax. Can be used indoors in a loft as it only measures eight feet across and is very light to handle.

Particularly recommended for those with restricted space.

Source g3ycc 

Single Coax Feed to Multi-Band Copper Cactus Antenna

Posted in UHF Antenna, VHF Antennas Leave a comment

There are three connection possibilities to feed the multi-band copper cactus antenna with a single feedline or coax.

However, it is imperative that you use the proper coax for the highest band of operation, RG58 just won’t cut it and even RG8 in lengths longer than 25 feet is marginal in 440 operation.

For all single coax feeding methods, the antenna will require re-tuning to obtain the lowest SWR for each band. This is accomplished by installing in the pipe cap of the tuning stub on each band of operation a brass machine screw of at least 2 inches in length vertical out of the cap.

The first and simplest connection method, albeit the hardest to tune, requires that you place a shorting wire on all but the lowest band of operation. If you are building your antenna from the N0ZOI (now KG0ZP) plans for “The Copper Cactus Antenna” and for example building a tri-bander for the frequencies of 144, 220 & 440 MHz, the shorting wires should be placed between the normal connect points for the shield and center conductor of each band. The 440 band shorting wire should be placed exactly 1 inch above the top of the horizontal pipe of the 440 tuning stub, the 220 band shorting wire should be placed exactly 1-1/2 inches above the horizontal pipe of the 220 tuning stub and your coax suitable for 440 operation should be connected exactly 2-1/4 inches above the horizontal pipe of the 144 tuning stub with the center of the coax going to the main vertical and the shield to the tuning stub (this is just the reverse of the connections shown on the plans and in the methods below), keeping the center conductor length as short as possible.


For best results, tune the antenna from the highest band to the lowest, however, using the shorting method does create quite a bit of interaction.

The second method is easier to tune than the first method, but does require placing 1/4 or 1/2 wavelength matching sections for all the bands of operation. If you are building a dual band antenna, the use of a T-Connector simplifies the project. Please bear in mind that you cannot use a 1/4 wavelength matching section on one band and a 1/2 wavelength matching section on another band, plus each band of operation requires the use of a matching section, including your lowest band of operation. Unfortunately, the connections will be inside the vertical section, a feat not easy to accomplish, but it does make tune-up much faster and easier than the shorting strap method shown above. The center connector of the coax matching sections is affixed to the tuning stub and the shield to the vertical section, keeping the center conductor length lead as short as possible.

The third method requires no antenna re-tuning from the specifications given on the plans and random length pieces of coax may be used. However, a relay switching assembly must be constructed inside a weathertight enclosure or the use of a duplexer for dual-band operation or tri-plexer for tri-band operation can be utilized. As above, the center conductor of the coax goes to the tuning stub and the shield to the vertical.

I will note that I have used random length coax, without *-plexers or relay assemblies, however, this method worked on only three of five duplicate antennas using the same random length pieces of coax on each. Each band showed an SWR of less than 1.025 to 1 until connected together, then two of the antennas showed an SWR of over 3 to 1 and three antennas were less than 1.8 to 1 across all bands without re-tuning. A little re-tuning brought the SWR down to below 1.2 to 1 on two of the antennas, but we could not acheive anything lower than the original 1.8 to 1 on the third. So if you use random length coax and no relays or *-plexers, good luck.

NOTE: The connect distance above the horizontal member on each band is selected for an impedance of around 50 ohms, moving the connect point up or down from this set point can and will increase the impedance as high as 650 ohms within a distance of 1/2 inch either side of the established proper connect point.

Article posted by KGØZP

Super Morse for MSDOS

Posted in Ham Radio Software Leave a comment

Super Morse is the original comprehensive Morse Code training program for the PC. Super Morse permits the user to learn the Morse characters in a very orderly way using several different methods, including one unique to Super Morse; build speed with special exercises; enhance existing operating skills with even advanced exercises; measure progress with a testing feature; and even operate via radio or telephone modem. Super Morse permits the user to change speeds and other parameters on the fly, use standard spacing or Farnsworth methods, and insert interference to simulate an actual radio contact.

The author is Lee Murrah, KY8T (ex WD5CID), 169 Bassett Pl., Bloomfield, MI 48301.

Download Super Morse (192 Kb)

Frequently Asked Questions

1. Is Super Morse available for Windows?

No. Super Morse is a DOS program, but it will usually run under Windows as a DOS application using the SM.PIF file and the loop timing method. In Windows 95 you will need to restart Windows in the DOS mode. Running in a DOS window or running from the DOS prompt may not work.

2. Is there a version of Super Morse for the Macintosh?

No. However, some users have reported that they are able to run Super Morse on the Macintosh with an emulator, although that will not work with versions 3.10 through 3.16 due to the timing method used. I have no plans to port Super Morse to other machines.

3. Can I send the code sounds through a sound card?

Yes, you can use the Sound Blaster card if you have the right version. Versions through 3.16 do not support the Sound Blaster card, but 4.01 and later do. Super Morse is unable to use the Sound Blaster when running in Windows if the Sound Blaster is set up as the Windows sound output device.

4. Where can I obtain the latest version of Super Morse?

Obviously you can download it from this Web page. The latest version of Super Morse is also always available on Compuserve HAMNET or at the Internet ftp sites ftp://qrz.com and ftp://ucsd.edu.

5. Do you have any circuits for interfacing Super Morse to my radio?

No, I have no circuits other than those shown in the DOC file.

6. Why can’t I just send you some money and have you send me a copy of Super Morse?

Publishing Super Morse is a hobby, and I have chosen not to make a business out of it. Therefore, I do not take orders.

7. Do you accept credit cards for the contribution?

No, but you can make a contribution via Compuserve by entering GO SWREG and selecting program number 649.

8. Is there a printed manual?

No. The “manual” is distributed in QUICK.DOC and ADVANCE.DOC which are ASCII files with page numbers and table of contents that can be easily printed on your printer.

9. Do you notify users of updates?

No. Unlike many other authors, I do not notify contributors when a new version is released–I just do not have the time. Watch this Web page.

10. What is your shareware fee?

I do not have a shareware fee per se. However, I do accept contributions to support development of the program. I suggest a donation of $20. Please do not send non-U. S. currency due to the high cost of currency exchange in Iowa. Instead send a postal money order denominated in Dollars.

10. Where do I send a contribution?

M. Lee Murrah
169 Bassett Pl.
Bloomfield, MI 48301