1
$\begingroup$

I have a Diamond HFV-5 (rotatable dipole) in the attic fed by ~30ft of coax. The antenna system comes with a Balun at the feedpoint. Would it be worthwhile to add an inline RF Choke (Unun) in addition or is that covered by the Balun?

https://www.diamondantenna.net/HFV-5.html

$\endgroup$
1
$\begingroup$

A balun effectively allows you to connect a balanced antenna (such as a dipole) to an unbalanced feeder (such as coax). You have a balun at the feed point of the antenna, with a coax socket on it, which means that the feeder going from the radio to the antenna is unbalanced.

The HFV-5 is an antenna that presents a 50Ω impedance on its coax socket and it already has a balun. Your radio's impedance at the antenna socket is presumably also 50Ω, and I am assuming that you are using 50Ω coax as the feeder.

I am puzzled as to what good the unun would do in this system.

(So to answer your question - I don't think it would be worthwhile to put an unun in addition to what you already have).

$\endgroup$
  • $\begingroup$ Thanks. I got the idea after I had a problem with a computer monitor turning off when transmitting on 20m (related to power supply). I was asked if I had a choke, but I assumed the balun that came with antenna would suffice. $\endgroup$ – Inisheer Oct 8 at 2:33
  • 1
    $\begingroup$ You assumed correctly. I have an HFV-5 not 10 feet from my computer screen, and don't have any problems with RF in the shack. I get more problems with computer noise getting into the antenna itself :) $\endgroup$ – Scott Earle Oct 8 at 2:34
  • $\begingroup$ Ok, thanks. Good to know you have the same antenna! de W0CD $\endgroup$ – Inisheer Oct 8 at 2:37
  • $\begingroup$ And you have the same antenna as HS0ZLW! :) $\endgroup$ – Scott Earle Oct 8 at 2:41

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.