I’ve actually used this kind of antenna. When I was a teenager, I used it with my old Realistic stereo receiver to improve its AM reception, and it did work. (My dad put it up for me.)
Continue readingThe Vertical Bazooka Antenna
An article by VE3VDC LD Blake
Every radio amateur should build at least one antenna to prove to themselves they can improvise in an emergency. One of the easiest and quickest antennas to build is the Vertical Bazooka, which is made entirely from coaxial cable.
Continue reading7 element Yagi for 20 Meters band
They say if it didn’t blow down it was not big enough, this one was big enough and it did blow, not off but up and over the top of the tower like an umbrella one very windy day in January 1974. I was at work and the XYL called and said the “thing” blew off the top of the tower- WOW, I imagined it in somebody’s living room. In fact it did not blow off it blew over the top, broke in two and slid down about ten feet an hung on the safety cable. When I originally built the thing I rigged this safety line of 3/8 inch aircraft cable from the tower to the four inch diameter boom just in case. I remember I used to laugh when I told people about the safety cable never thinking it would actually blow off the tower. The storm was really a bad one, very high winds with ice covering the boom and elements. In fact a drive in movie screen blew over just down the street from me. It was a very sad occasion, I was the one sad and the neighbors were glad. The obliging neighbors called the building inspector and he was waiting for me when I got down from the top after attaching a rope, disconnecting safety cable and cutting the coax cable and letting it down, smoothly. The inspector notified me that one of my neighbors said that it had blown down three times already this year. This beam worked very well for me for several years.
I apologies for the quality of the photo. Its the only one I have. What you see is what you get. Very narrow beam pattern, that’s not QSB man that’s my beam swinging in the wind.
The omega match was motorized because it was so far out on the boom.
CAT Interfaces for ICOM YAESU Kenwood
Icom appears to delight in charging outrageous prices for all transceiver accessories, so many Hams improvise instead. A few circuits have been published for CI-V interfaces, most of which use the MAX232 IC. Here is a very simple CI-V interface, originally described by OK2WY . I’ve made small changes to the modem control signals connections. Although the circuit doesn’t conform exactly to the RS-232 specification, it does work well and has the advantage of being easily constructed inside a 9 pin D-type shell. Please note that the resistor value 4K7 means 4700 ohms. The transistor types are not critical, I just happen to have plenty of 2N2222As.
Continue readingGAP Titan DX Maintenance
I’ve installed the GAP Titan DX some years ago. Due to maintenance works on my roof, I had to put the antenna down for some weeks.
This week I’ve been able to restore the antenna on the roof. The Gap Titan DX is a vertical dipole with no traps, and with vertical elements making this antenna resonating on from 12 to 30 meters. 80 meters provided from a top capacitor, while 10 and 40 meters depends on the tuning of a cross shaped counterpoise at the base of the antenna.
I’ve already written several times about this antenna and how to tune it on several bands providing also a quick antenna reference you can seen here behind.
According to some OM there is a relation between the 20 meter stub and the 40 meter copper wire length.
Well, today after having restored back the antenna on the roof, I’ve not been able to obtain an acceptable SWR on the 40 meters.
With acceptable I mean SWR < 2.0 on the band. According to GAP this antenna shoud be able to perform well with acceptable SWR on all bands, but in the 10 years I’ve on the top of my head, it never performed on the 30 meters. SWR on 10 MHz has been always > 3.5.
Continue readingWonder Whip Antenna
The Wonder Whip?
A £10 QRP Portable Multiband Antenna for HF, VHF and UHF
A variation on the “Miracle Whip” and “Wander Wand”.
The Wonder Whip
Florence RadioFest 2019
on Saturday 25 May 2019 i will take part to the upcoming Florence RadioFest as organizer.
The Florence RadioFest is a local amateur radio HamFest managed by the members of the ARI Section of Florence.
We expect to have over 50 private amateur radio oeprators and more than 10 amateur radio business companies represented.
Quarter Wave Vertical Antennas
and how they operate
One of the most useful antennas in the repertoire is the
Marconi or quarter wave grounded vertical antenna. Its invention made
it possible to halve the length of antennas, simplifying communications,
especially at HF and below. This antenna is still used widely today,
especially in marine, land mobile and long distance communications. It
can offer excellent performance when installed well. There are, however,
a number of selection criteria to take into account before you buy…
Long Waves, Short Antennas
designing for MF and LF communications
When radio began, it started with low frequency communications, which it was thought was the answer to long distance communications. Since then we have seen the development of sky wave communications on HF frequencies, followed by the proliferation of communications system using the VHF and UHF direct wave and microwave. It may be thought by some that low and medium frequency communications are somewhat outmoded, but in reality they are still very much in evidence today…
Feeder Radiation
Striking a Balance
When you connect centre fed antennas, like dipoles, Vs, triangles, yagis, rhombics, loops and so on, to coaxial cable, unless care is taken, it is not difficult to end up with feeder radiation. Not only can the loss in power be quite significant, but the radiation characteristics of the antenna system will also be seriously compromised.
Continue reading