Paddling And Coupling The Rock-Mite 40 For The Field
By Steve Yates, AA5TB
Special to The ARS Sojourner


A short time ago I took some time off and played a little radio.

I built a small set of paddles out of a discarded "switchcraft" panel mount lever switch and an end-fed halfwave antenna coupler using a polyvaricon capacitor out of an old radio and a T-50-2 core.

Both were constructed in old "Panoma" boxes (don't ask where to find them these days). Both were for use with my 40-meter Rock-Mite. For power I can either use the internal 9-volt battery for about 250mw output or the external AA battery pack for about 470mw output.

I built the setup for a planned camping trip but circumstances were such that I didn't get to go camping so I at least set up in the backyard with the portable setup including a temporary end-fed halfwave antenna.

Many times the only trees that I have available while camping locally are some short cedar trees. So I purposely installed the antenna up horizontally at a low height using temporary poles to simulate the low trees. I expected this to be good for at least NVIS work on 40-meters.


Tuning of the antenna coupler is so sharp that I can just peak up on receiver noise and the antenna will be at or very close to a 1:1 SWR. Therefore, I didn't include a SWR indicator this time.


The setup worked great and I made a bunch of contacts with it. When I get some more time I will put greater construction details on my web page regarding the accessories: http://www.qsl.net/aa5tb/rockmite.html



The antenna coupler is designed internally much like this one at: http://www.qsl.net/aa5tb/coupler.html – but without the SWR indicator.


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Steve Yates, AA5TB, is a longtime QRPer, expert builder and avid field operator living in Forth Worth, TX.