The QRPer Board

I built and tested an EFRW / 9:1 Unun antenna with 29.5 ft (9m) radiator and single 17 ft (5.2m) counterpoise. With Elecraft KX2 internal tuner, I can reliably tune 60m to 10m bands. I am using it for QRP CW field (POTA) operations, and have had a respectable number of contacts. Deploying it is very simple using a throw line over a tree branch to pull the radiator up with near-vertical geometry. It will be taking up residence in my field kit.

This is a great configuration for the KX2! Great to hear good results. How long is your second counterpoise? I’m assuming you are using coax between the radio and 9:1.

N5FY wrote: ↑Fri Jan 17, 2025 12:47 pm This is a great configuration for the KX2! Great to hear good results. How long is your second counterpoise? I’m assuming you are using coax between the radio and 9:1.

LOL! Second counterpoise was15 ft of RG316 in a bit of a curly-cue configuration. WX here kept me in the truck for my activations / testing. Feedpoint was clipped to the VHF/UHF antenna on the fender, and coax drooped down before entering through the bottom of the door seal.

Best 73 de Brian - K3ES

Brian,
My home antenna is a 35.5/17 EFRW. It works pretty well on all bands, but tuning for 40m is very touchy. I'm thinking of going with a 33 or 35.5 foot counterpoise.

73,
Mike, KL7MJ

KL7MJ wrote: ↑Mon Feb 03, 2025 6:49 pm My home antenna is a 35.5/17 EFRW. It works pretty well on all bands, but tuning for 40m is very touchy. I'm thinking of going with a 33 or 35.5 foot counterpoise.

Hi Mike,

Joshua - N5FY (2nd post above) makes great portable QRP EFRW antennas that are sold at Tufteln.com. One available configuration is 35 ft radiator and 17 ft counterpoise, and I have had great success with that particular Tufteln antenna for field operations.

Admittedly, I am spoiled with my EFRW antennas because I pair them with the excellent tuners in my KX2 and KX3 rigs from Elecraft, so tuning on any reasonable band is quick and easy. I will say that the 29.5 ft radiator version is not long enough to get a good match on 80m, and even if a match were to be achieved, efficiency would be poor. Also, I limit my field operations to 5 watts, so "RF in the Shack" is of little concern. For higher power, optimized counterpoises, chokes, and grounding may be important considerations. I have not experimented with EFRWs for QRO operations.

Best 73 de Brian - K3ES

Brian - K3ES wrote: ↑Wed Jan 15, 2025 4:20 am I built and tested an EFRW / 9:1 Unun antenna with 29.5 ft (9m) radiator and single 17 ft (5.2m) counterpoise. With Elecraft KX2 internal tuner, I can reliably tune 60m to 10m bands. I am using it for QRP CW field (POTA) operations, and have had a respectable number of contacts. Deploying it is very simple using a throw line over a tree branch to pull the radiator up with near-vertical geometry. It will be taking up residence in my field kit.

Almost exactly what I use when operating in the field. 29 ft of wire with about a 15 ft counterpoise. Rig is either a K2 or TR-35 with a 4-State tuner into which I installed a 9:1 transformer.

being able to "load" or "tune" if you prefer does not mean efficient radiation a dummy load will "tune" just fine

Andrew (grayhat) wrote: ↑Sat Mar 22, 2025 11:26 am being able to "load" or "tune" if you prefer does not mean efficient radiation a dummy load will "tune" just fine

Whenever I use mine it works fine. Certainly not a dummy load.

also

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