[ARC5] Antenna for small yard

Mike Everette radiocompass at yahoo.com
Fri Oct 21 18:26:22 EDT 2016


Take a look at the article on converting and using ARC-5 and SCR-274N transmitters found in ARRL Handbooks from about 1960 through 1967 or 68.
I think this was originally written by Lew McCoy, who had a great reputation for knowing what he was doing.
It refers to use of 1/8 wavelength antennas, i.e. 33 feet for 80 meters and 16 feet for 40 meters.  The tips for matching and tuning are interesting.
73
Mike
WA4DLF

      From: J Mcvey via ARC5 <arc5 at mailman.qth.net>
 To: AKLDGUY . <neilb0627 at gmail.com>; ARC-5 List <arc5 at mailman.qth.net> 
 Sent: Thursday, October 20, 2016 10:17 PM
 Subject: Re: [ARC5] Antenna for small yard
   
Hello Neil,
I was experimenting with the 40 meter Tx antenna in the spring to see what length it would tune to. I hoisted one end of the wire up in tree and hooked the other end to the TXIt was amazing small, only about 23 feet (about one third the size of a half-wave), if memory serves.So, I suppose you would need about 46 feet for the 80 meter.
I looked but couldn't find the right manual, but one of the ARC-5 or SCR-274 manuals has a whole description of recommended antennas in it.
They used straight wire, L, and T types. The T is modeled like a vertical with a top load.

A long wire will be HI-Z, which you may be able to match with cap to ground at the antenna terminal which makes a L section impedance match with the inductor.

Dave Simson said that he could match 50 ohm systems with a series 50 pf cap. 

    On Thursday, October 20, 2016 4:07 PM, AKLDGUY . <neilb0627 at gmail.com> wrote:
 

 Can anyone suggest a suitable antenna for 80m designed for low impedance transmitters such as the BC-230 and ARC-5?
My yard is 24 feet (7.2m) x 12 feet (3.6m) with a 5 foot (1.5m) high wooden fence on three sides. The ground is covered with concrete pavers, so burying wires is not an option. I do not want to erect poles, so the fence will be the only support.
I have a 2m J-pole mounted out on the fence with RG-213 coax dropping down and running across to the door. I figured that this might act as "the body" of a plane, so I disconnected the coax from my 2m transceiver and connected the braid to the Ground terminal of the BC-230.
Then I ran out a wire from the BC-230 antenna terminal out to the fence very close to the J-pole. This wire was about 4 feet high, and I figured that the whole thing might approximate a short antenna above a plane body. Unfortunately, no antenna current was indicated on the BC-230's RF ammeter. It normally shows about 0.6 Amp when operated into a 5 ohm dummy load in series with 150pF (ARC-5 transmitter cap).
Is anyone able to model that entire thing as an 80m antenna, or can anyone suggest a better arrangement?
73 de Neil ZL1ANM
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