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

[Gary Schafer]

High capacitance per foot on the cable. In the high impedance mike 
circuit a little capacitance will kill the highs.

73
Gary  K4FMX


Brett Gazdzinski wrote:
> The R390a is sold, Bob (wa3gfz) jumped on this one and picked it up
> last night!
> 
> I have had that R390a for about 20 years, and its been working fine
> for the last 15 years at least, after a rash of broken gear clamps
> the first couple of years I had it.
> I hope Bob has as good a performance from it as I did.
> 
> I don't know how things are normally done as far as selling,
> but I think Bob actually called my house first, and left a message
> with my son.
> 
> I still have the like new SX17, which I thought sounds better
> than the R390a audio off the detector into the Marantz amp.
> 
> I now have an almost empty rack for the new project, I may move
> the push pull 812a rig rack into its spot, if I can find a place
> for the audio power amp, the only thing in the rack now.
> 
> Or, maybe I will leave the racks in place and move the 812A
> rig into the empty rack, its closer to the operating desk.
> 
> The new rig (pair of 4D32) is coming along nicely so far,
> the RF deck is drilled, punched, and painted, just needs to be
> assembled, then its onto the RF control deck.
> I am making the decks so they can be used with anything,
> variac bias supply, variac screen supply, etc.
> The RF deck is 40 meters only, but if I want, I could build an
> 80 meter deck to go with the 40 meter one.
> 
> The push pull parallel KT90 modulator deck is laid out parts wise,
> and I have all the parts needed for it.
> 
> One power supply deck parts are gathered, I think I will do separate 
> variac supplies for RF and modulator decks.
> 
> I made an interesting discovery Sunday.
> 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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