Planning to setup a double bazooka antenna for 7 MHz during next months to verify performance of the Gap Titan DX on that band.
I feel like the GAP is not so well performing on that band and I’m goint to setup for the CW portion of the 40 meters.
This is the basic schema I’m going to follow
Santa recently dropped this lovely gift to my son…..
Well, I had to learn a little bit about how to use it before I taught him.
I got inspired by the IARU World Amateur Radio Day leafleft..
Here a short vertical antenna for top band, designed by I5CDF Riccardo Rossi for IK5TBK Stefano.
I’ve recently introduced a Raspberry PI 4 as main remote RTX controller for my Kenwood TS-590s.
This allows me to control the Kenwood TS-590S from the iMac simultaneously with several applications, including RUMLOG, FLDIGI, WSJT-X.
The issue
Could not control simultaneously my transceiver directly from two or more applications. Additionally remote connection from the internet requires a PC always turned on or at least the possibilty to power on with wake-on-lan
Cause
The usage of the USB Port is exclusive
Workaround
An alternative solution is to run the FLRIG on the iMac, and connect the applications to the local loopback 127.0.0.1.
I’m using RUMLOG by DL2RUM as main logging program both as main logging and for contest logging as well. FLDIGI for common digital modes and WSJT-X for weak signals digital modes.
What do you need
On the MAC you need to reconfigure the programs, in order to use FLRIG as Radio. Basically FLRG acts as a gateway to your radio.
Rumlog configuration
FLDIGI Configuration
WSJT-X Configuration
On the Raspberry you need to configure the connection with the USB to Serial cable connected to the RS-232 port of the TS-590S.
If you have issues on selecting the USB Port or you have multiple one, check the status of the USB connections with lsusb command
pi@raspberrypi:~ $ lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 0d8c:013c C-Media Electronics, Inc. CM108 Audio Controller
Bus 001 Device 005: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
Bus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
| Dimentions | Elements |
| A, B, C | spacing between elements 119.38 cms. |
| E 1 | Reflector 1: 304,8 cms. |
| E 2 | Radiator : 274,32 cms. |
| E 3 | Director : 271,15 cms. |
| E 4 | Director: 269,24 cms. |
| D | Distance with gamma match: 35, 56 cms aprox. |
| E | Gamma spacing: 7,62 cms. |
| F | Gamma tune: 50,8 cms x 12,5 mm diameter |
Elements are 12,5 mms.diameter
Inside the F part, insert an RG213
The sheath is introduced inside F with a 30.48 cm RG213
The Boom is built with a 5 cm rectangular aluminum tube. wide by 7.5 cms. High.
By Lew McCoy, W1ICP
QST September 1972, pp. 14-16, 28
DURING DISCUSSIONS with newcomers, and old timers for that matter, it becomes apparent that there is considerable confusion as to what exactly a multiband vertical antenna is. The confusion concerns the method of feed, how much mismatch one can expect, how many radials are required, how the particular antenna is built for multiband use, plus some other points.
This article breaks the subject into simple language and provides the reader with sufficient expertise to assure him that he won’t wind up with a system he really doesn’t want Before going into a discussion of the different types of multiband “verticals” we will offer some simple antenna facts.
Some Basic Theory
The term “multiband antenna” has come to mean many things to hams. With trap antennas, tapped coils, random wires, and so forth, there is plenty of reason for the confusion. Simply, a multiband antenna is one that can be used on more than one band. How we make it work on different bands is another story.
Continue readingThe Clemens match is easy to make and reliable, and is preferable to a single Gamma match as it is balanced.
I was first introduced to the Clemens match by G4IGO several years ago, Ken builds his in a slightly different way by putting the capacitor at the feeder end and connecting the far end directly to the boom. Both methods appear to work equally well.
The cable clips used are the black polythene types used to secure steel wire armoured cable to walls etc.
The length of the copper tube for matching at 50.110 MHz is 5.98683 metres * 0.125 = 0.748 metre or 29.455inches.
Put the Clemens match on the underside of the driven element to prevent large birds from damaging it.
I think it is preferable to connect the feeder braid to the centre point of the dipole also, as this helps to prevent unwanted currents flowing in the outer back to the tx.
Water proofing the joints etc. is very easy if plenty of polyeurothane varnish is painted on to them. This must be checked yearly to check for any signs of cracking or flaking.
I use LDF250 feeder from my rotator to the Clemens as this makes construction very easy. The outer plastic sheath is stripped from where the coax joins the dipole element. This gives continuous contact of the outer with the element all of the way along. Once liberally painted with clear polyeurothane varnish it is totally water proof, and corrosion will not take place.
Tuning is a matter of starting with the copper tube about 4 inches (10cm) away from the driven element, with loop of RG58 inner soldered to the copper tube at one end, and to the inner of the feeder at the other end. Attach another length of RG58 inner to the driven element at the other end of the copper tube. Make it about 12 inches (30cm) long. I secure it to the element by trapping it under a stainless steel jubilee clip. Using an antenna analyzer, (or low power tx and swr bridge) set to the design resonant frequency of the antenna. Push the RG58 inner into the copper tube until a dip in the swr is seen, then move the copper tube nearer to the driven element by a few mm. Move the RG58 in or out of the copper tube until a further dip an the swr is seen. Continue this process of moving the copper tube, and moving the RG58 inner in the tube until the lowest possible swr is obtained. Trim the lengths of the RG58 at each end if the loops in them become too large, until the final setting is arrived at. Finally, if you have left the driven element length slightly long as suggested, trim it by removing 1mm or so from each end and retuning the Clemens to the lowest possible swr. Do this very carefully, as you cannot easily make the driven element longer again if you cut it too short.
This process should be carried out with the antenna mounted so the reflector is 2 to 3 feet (55 to 90cm) from the ground and the rest of the antenna pointing at the sky. Next, before you finalize the Clemens, hoist the antenna in the air and find out how far the resonant frequency has moved. It usually drops by 50 to 100KHz. For this reason it is better to tune the antenna initially at a frequency of 50.210 MHz (for instance) so that when in the air the antenna is at the correct resonant frequency. This prevents the need to hoist the antenna up and down several times.
If you are satisfied that all is well, having connected the antenna to the feeder that will be used, and checking that the swr measured at the rig in the shack is no different to that obtained when tuning near the antenna. You can then substitute the pieces of RG58 inner used for tuning by a couple of new pieces cut to the correct lengths. make sure the loops at the ends are not excessive. Once every thing is in place, paint all the joints and exposed coax ends with a liberal amount of polyeurothane varnish. Do not paint the whole length of the copper tube as the resonant frequency of the matching will be moved slightly by the dielectric constant of the varnish.
Check, and check again that the swr is ok (it should be 1:1). Once satisfied you can install the antenna in it’s final position.
The resonant frequency will alter slightly in wet weather and will tend to drop a few KHz.
Taken from a usenet post by John Doty in 1996
In article <9612182335114148@mogur.com> len.anderson@mogur.com (Len Anderson) writes:
> TV>> I wonder if a longwire balun would help match the impedance & provide a
> TV>> better signal?
> No, it will (primarily) change only the magnitude of the antenna
> impedance over frequency. Some bands will have more sensitivity than
> other bands. The antenna tuner will take care of that.
Actually, a fixed matching transformer can dramatically reduce the wild swings in antenna efficiency that a coax fed wire antenna exhibits. Let us calculate:
The following graphs are based on a 15 meter vertical antenna, fed at ground level, using a conical approximation. The antenna’s characteristic impedance is assumed to be 620 ohms, which is typical for a thin wire. For more on the conical approximation, see Chapter 8 of “Antennas” by John D. Kraus (McGraw-Hill, 1950).
The first graph is for an antenna fed directly from 50 ohm coax. The horizontal axis is the frequency in MHz, the vertical axis is the mismatch loss in dB. The well known “quarter wave” resonances near 5, 15 and 25 MHz are visible as sharp peaks where the mismatch loss closely approaches zero.
The second graph assumes a matching transformer with a 9:1 impedance ratio at the feedpoint, presenting the antenna with a load resistance of 450 ohms. At most frequencies, the mismatch losses are considerably lower for this case. The variation in the mismatch loss is also reduced:
Well, so what? In the absence of interference, the signal to noise ratio is the main determining factor for the audio quality of the signal.
The mismatch loss affects both signals and noise, so if the receiver was noiseless the losses would not affect the signal to noise ratio.
Real receivers, however, are not noiseless: if the loss is too high, receiver noise will become dominant, and overally system sensitivity will suffer.
The following results assume cosmic noise of 29 dB above thermal at 10 MHz, declining with increasing frequency at -23 dB per decade. No man made or atmosperic noise is assumed. I assume a receiver noise figure of 10 dB.
First, here is the signal to noise impact of the mismatch losses for a 50 ohm coax feed without a transformer:
Losses in signal to noise of 3-5 dB are likely to be noticeable. The largest impact is in the quiet bands above 15 MHz.
On the other hand: the loss in signal to noise with a 450 ohm feed is much smaller:
You are unlikely to be able to notice losses in signal to noise in this range.
The results depend on the assumptions. A real longwire isn’t usually vertical: this tends to degrade its performance a bit at the low frequency end, while improving it at high frequencies. This is good, because in the model the signal to noise is declining as the frequency increases: the increase in performance cancels part of this.
No man made or atmospheric noise is included. If they are significant, the precision of the match becomes less critical. Man made noise can be significant at any frequency, but atmospheric noise is more significant at the lower frequencies.
A receiver noise figure of 10 dB is mediocre for a solid state receiver or a tube receiver with a triode RF amplifier. Tube receivers with pentode RF stages may be a bit worse than this, and something like a Hallicrafters “Sky Buddy” (no RF stage, pentagrid converter) might have a noise figure >30 dB. The better (smaller) the noise figure, the less you have to worry about matching. Sky Buddy owners will want to tune their antennas very carefully.
I haven’t included cable losses here. These are not terribly important unless you’re using an ATU at the receiver end. If you are, using a fixed transformer to get the match roughly right at the antenna end will reduce the cable losses, because cable losses increase with increasing SWR.
My own experience concurs with the results of this theoretical analysis (or I wouldn’t be writing about it: I’d be trying to figure out what was wrong!). I have experienced “deaf bands” with coax fed antennas lacking matching transformers, but my transformer-fed antennas work well across the HF spectrum (and even down to longwave). I don’t bother with an ATU.
A good antenna that can be used for the car as well as the house is an HALO. This antenna maintains good omni-directional horizontal polarization. Basically the antenna is a half wave dipole bent into a circle,BUT shorter than a dipole for this frequency. The circumference is 60-70 inches. By useing the gamma match (see above) you can use regular coax.This is a high-Q antenna.So bandwidth is about 200khz. (Perfect for 50.100-50.200 where most of the 6m ssb activity is)
The 2 large discs can be about 4-5 inches round and the small disc about 1.5 inches. Mount the 2 larger discs at the ends of the halo by screwing end caps to the center of them and then the end caps will go over the ends of the halo. Next drill a small hole in one of the larger discs and the same size hole in the exact center of the small disc. Put a 2 inch bolt threw the center and run a nut up the bolt to lock it in place. Then a nut on each side of the large disc to secure the bolt to the larger disc. Mount the gamma rod the same as you did on the beam (see above) BUT bend the gamma to match the curve in the halo. Finally take three 2-3 inch nylon spacers and mount them between the large discs. You should drill 3 holes in a trianle patern and use 3 nylon bolts and nuts. This will ensure that the ends plates do not move around on you. You can mount this antenna on a mast by making some type of bracket for support.
(Just try to put the bracket by the mount where the coax/gamma is so that the mount should not affect the antenna preformance.)
To match the antenna simply move the gamma around a few times(move it in small increments it really tough). Once you get the S.W.R. down below 3:1 then move the small disc by loosening the nut and turning the small disc.(AGAIN move it in small increments)
Use a 54” piece of 450 ohm Ladder line.
Cut out 3 inches of the center part of the ladder line.
Solder a PL-259 on the bottom of the Ladder Line (both side of the ladder line will solder on the ground side of the PL-259 – this is used for the shorted part of the J-Pole).
Cut a 1” PVC pipe 1 1/2” long.
Cut a 36” piece of RG-174 coax.
Wrap the coax around the PVC pipe.
One end will attach to the PL-259, the center of the coax will connect to the center of the PL-259 and the shield of the coax will connect to the outer portion of the PL-259.
Strip the insulation off lh ladder line 2 1/2” above the PL-259.
Attach the center of the coax to the side that will have the long wire attached, the shield side of the coax will connect to the short side of the J- Pole.
Connect the Long wire to the ladder line.
Check the SWR, if it is not less than 2:1 in the operating portion you want to operate, you can tune the J-Pole by moving the tape of RG-174 up or down. Do not move it more than ~ 1/4” at a time
Article originally available at http://www.wb5cxc.com/6m_jpole.html