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Author Topic: Mystery Monoband vertical????  (Read 2202 times)
AF6NI
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Posts: 7




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« on: March 09, 2012, 11:35:16 AM »

I just picked up some ham gear at a yard sale and one of the items appears to be a commercially produced vertical that is I think is a 20M monoband.

It's still in pieces and so I haven't mounted it so a picture could be taken but is is about 17' long with three 4 foot counterpoises. It is collapsed and the middle section telescopes into the bottom part. The top section is separate. It also has a capacity hat built into the top element (3 small aluminum rods about 8" long that can be rotated.) There is a mounting plate for the counterpoises and the mounting bases appear to be similar to HyGain antennas. There are no traps.

I don't have any idea who has ever produced such an antenna. Any guesses or info would be appreciated.

73.
Joe
AF6NI
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WB2WIK
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Posts: 20542




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« Reply #1 on: March 09, 2012, 11:41:31 AM »

Is it "directly fed?"  That is, does the center conductor of the coax connection at the bottom obviously attach directly to the vertical radiator, with nothing in between?

Or is there an assembly near the base where the coax connector is at the bottom and the vertical radiator connects to the top, and there is evidently something in between (like a molded piece, etc)?

If the latter, I'd say it was a CB antenna with a matching transformer at the feedpoint.

If there's no matching system at all, then it sounds like a 20m 1/4-wave ground plane but I can't recall anything like that being on the market.
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W5DQ
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« Reply #2 on: March 09, 2012, 01:32:27 PM »

Sounds very similar to the old standard CB vertical antennas we used to sell at my dad's CB shop back in the 70's. I'd bet you got youself a piece of 'good buddy' history there  Grin

I also don't recall ever seeing a 20M monobander vertical made for sale commerically anywhere in my 35 years as a ham. Of course I wouldn't know about any the one off antennas that came and went or were sold locally out of someone's garage.

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
AF6NI
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Posts: 7




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« Reply #3 on: March 10, 2012, 06:25:18 AM »

Yes indeed its center fed. Sure looks like a 20m monobander, but commercially made.
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WB6BYU
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Posts: 13017




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« Reply #4 on: March 10, 2012, 08:32:22 AM »

Are you sure about the radial lengths?  Do they have loading coils?  4' is pretty short for 20m
radials.

If I just model the 17' vertical with 4 horizontal 4' radials, it is a good match to 50 ohms around
17m to 15m (and could be used on either band with adjustment of the radiator length.)  But
that assumes perfect feedline decoupling, which is unlikely to occur in practice.
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WB6BYU
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« Reply #5 on: March 10, 2012, 08:44:07 AM »

Shorten the radiator to about 14' and it tunes on 6m, but the pattern isn't very practical
unless the radials are longer.
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KA5N
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Posts: 4380




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« Reply #6 on: March 12, 2012, 01:02:56 PM »

CB antenna.    I have never seen a 20 meter GP with fixed radials.  They would need to be
about 17 feet long as well. 
CB antennas were often built for looks rather than performance.  The more gadgets you could
hang on the better.

Allen
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N1BNC
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Posts: 12




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« Reply #7 on: March 14, 2012, 03:14:54 PM »

This sounds like a Radio Shack 5/8's wave vertical. The aluminum bracket at the base is U shaped and has space for two u-bolts, and the insulation is gray and the "radials" are held by two triangular plates and there is a screw in each of the radials in these plates keeping them there. The so-239 comes out the bottom.

Does this sound about right?

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KW6LA
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Posts: 91




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« Reply #8 on: March 14, 2012, 06:31:07 PM »

 

This is the Hy-Gain model CLR-2 5/8 wave omni-directional ground plane antenna. This is also virtually identical to the "Colinear" antenna marketed by Radio Shack. This antenna sported 3 102" radials, as well as 3 small 8 inch "radials" at the top of the antenna to reduce static build-up. This antenna had an advertised gain of 4 dbi, and was one of the most popular CB antennas in the 1970's.
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KE7ZOI
Member

Posts: 6




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« Reply #9 on: March 25, 2012, 09:17:26 AM »

 ;)I have A clr-2 5/8 wave antenna. If you shorten the main mast 6in. it tune up on 10 meters with a very low swr. It will also handle 100 wats all day long, just ask me.
 73 dave ke7zoi/ka7qno
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