Shortwave USB

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Shortwave USB

Postby mike43 » Thu Oct 27, 2016 3:58 pm

Listening on USB the other day to RAF Volmet on 5.4500Khz, not a bad signal. I made myself an antenna tuning unit or matcher a while ago for my random wire antenna which works OK. My question is can I use the unit on SSB or USB at all. I wired the radio through the unit but nothing seemed to change with the 12 way switch or the variable caps or the antenuator. I must be missing something here, the unit works elsewhere, can the forum's members put me right on this. Thanks, Mike
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Re: Shortwave USB

Postby m0lsx » Thu Oct 27, 2016 4:04 pm

A AMU works to match the impedance of the antenna, be that high or low, to one the radio would rather see. It makes no difference what the mode is, it's the impedance that is altered & that is the same regardless of mode.
Personally with amateur radio. I always set the AMU, be it manual or auto using a low power FM signal, then switch to upper or lower Side Band.
I would guess as a SWL, you are tuning for loudest audio? If so do that on AM & then turn over to SSB.
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Re: Shortwave USB

Postby mike43 » Fri Oct 28, 2016 4:05 am

Thanks for the advice Alan, will give it a go.
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Re: Shortwave USB

Postby m0lsx » Fri Oct 28, 2016 8:55 am

On RX, AM rather than FM is probably better as the noise levels are higher, so you will notice the antenna peak easier when you tune. Which is probably why you are not noticing any real difference on SSB. The noise levels are lower, so you cannot match the antenna as easily.
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