[AMRadio] RE: r390a, sx17, t4xb for sale

[George Pritchard]

Gentlemen,
Most guys think that using the RF cable is good for eliminating RF
feedback into the input audio system. True, but a better way if your
using high impedance line (low capacity type) is to add a second braid
on the outside of the audio cable for RF reduction. The low dielectric
constant of the inner insulation will prevent the high freqs in the
audio from being attenuated when the additional shield is added. I have
added a braid over thick balanced 600 ohm line with no problems out to
ten feet or so. In any case, keep the mike cable as short as possible so
the mic doesn't get "hot" on 10 meters (1/4 wave antenna is 8 feet or
so). I now use 5 feet on the balanced mic cable (with the shield added)
to be clean on TEN AM with the 4X1. NO RF in audio.
George AB2KC

-----Original Message-----
From: amradio-admin at mailman.qth.net
[mailto:amradio-admin at mailman.qth.net] On Behalf Of Mike Dorworth K4XM
Sent: Tuesday, January 13, 2004 12:21 PM
To: amradio at mailman.qth.net
Subject: Re: [AMRadio] RE: r390a, sx17, t4xb for sale

50 ohms is 50 ohms, plus 20 pf per foot cap all are killers! Mike,K4XM
----- Original Message ----- 
Subject: Re: [AMRadio] RE: r390a, sx17, t4xb for sale


>>> > I have had a few reports of my audio not having a lot of highs,
> > even though I boost the mid and upper voice frequencies.
> > There is nothing to limit the highs in any of the rigs, other
> > than the mod iron, and even crappy mod iron will typically pass
> > high enough frequencies to sound good, and found the cord between
> > the mike preamp and the power amp was the problem.
> > It was a 15 foot piece of rg8m, the little coax, with phono
> > ends on it.
> > You would think something that works for RF service up into VHF
> > would be able to pass high audio frequencies, but no.
> > I wonder why it was so poor for audio, cutting stuff above
> > about 3000 cycles a lot????
> > 
> > Brett
> > N2DTS
> > 
> > 
> > 
> > 
> > 
> > 
> >>-----Original Message-----
> >>From: amradio-admin at mailman.qth.net
> >>[mailto:amradio-admin at mailman.qth.net]On Behalf Of Brett Gazdzinski
> >>Sent: Monday, January 12, 2004 11:13 AM
> >>To: amradio at mailman.qth.net
> >>Subject: RE: [AMRadio] RE: r390a, sx17, t4xb for sale
> >>
> >>
> > 
> > 
> > _______________________________________________
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> > AMRadio at mailman.qth.net
> > http://mailman.qth.net/mailman/listinfo/amradio
> > 
> 
> 
> 
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