[Amps] Dual tetrode in grounded grid

[Glen Zook]

I am VERY familiar with the characteristics of RG58/U.  In fact, I used to buy it by the 1000 foot spools and use it for "leaky line" antennas for 960 MHz 47 CFR Part 15 installations in places like warehouses and I have used it for both highband and UHF installations for paging installations in places like hospitals, dropping the line down the elevator shafts and running it above suspended ceilings.  Frankly, it works at least as good as, and in some applications better than, Andrew Radiax which was running about $5 per foot versus 10 cents per foot that I was purchasing RG58/U for at the time.

I purchase 500 foot spools of RG58/U a couple of times a year to use in the interconnect cable kits that I make for Collins, Heath, Drake, and other manufacturers.  I absolutely refuse to supply used coaxial cables in these sets.  Collins specifications call for RG58/U cables, 4 feet long, in all the r.f. applications for interconnecting the various S-Line units together and the KWM-2 series to certain accessory units.  The remaining cables are shielded.  Heath uses RG58/U for the antenna connections (RG62/U for the BFO, heterodyne oscillator, and LMO connections) and shielded cables for the audio and control functions.  Drake also uses RG58/U for the antenna connections.

Also, RG58/U is the cable of choice for most mobile antenna installations (i.e. supplied by Larsen, MaxRad, and so forth).  Of course these applications generally come with 17 feet of cable attached to the mounts.  You can cut off extra cable but 17 feet is enough to get from the roof of the vehicle through the interior and then to the radio.

The few "hamfests" that are in this part of the country don't usually end up with RG58/U being thrown in the dumpster.  I don't know about your part of the country, but not in this part of Texas.  Besides, since I do have to purchase RG58/U for use in the cable kits when I do need a short piece I just cut it from the spool.

I do use RG58/U for connections (jumpers) from various antenna switches to receivers and usually for connections from transmitters that are in the 100 watt output or less class on frequencies below 30 MHz.  However, I do not use RG58/U for any longer runs nor for equipment operating above 30 MHz or for transmitters running more than around 100 watts output.  In fact, all of my antennas (1.8 MHz through 432 MHz) except for my 40 meter phased verticals have either 1/2 inch or 7/8ths inch Heliax.  I know that 1/2 inch Heliax is an "overkill" for such low frequencies but I have obtained a pretty large number of 100 foot runs of 1/2 inch Heliax at no cost over the years and to use anything less expensive would require a cash outlay.  I do use RG213/U on the 40 meter verticals because of the lengths required make coiling up of one leg necessary and Heliax is not easy to coil.  100 feet just happens to be the correct length to make it from the top of my main
 tower to about 3 feet inside the ceiling in my main radio shack.  From there (the last 4 feet) the jumpers are RG213/U to my antenna switches.

Right now there are 8 runs of 1/2 inch and 1 run of 7/8ths inch Heliax up my main tower and 4 runs of 1/2 inch Heliax up my "short" tower.  There are some photos of my antennas at

http://k9sth.com/uploads/newantenna.JPG

However, the 27 element 432 MHz yagi is not in those photos.

Glen, K9STH

Website:  http://k9sth.com


--- On Thu, 2/12/09, Carl <km1h at jeremy.mv.com> wrote:

I never assumed anyone had to BUY RG-58. That stuff winds up in the dumpster at hamfests ever sine RG-8X came along. Plus the older the better for loss.
 
Now thats a real no brainer.