[Johnson] valiant audio problems

[gbrown]

Ronnie;
    Are you using a wrong impendance mic on the Valient??? Is the D-104,
ceramic or dynamic?
Regards
Gary...WZ1M

http://Tubes_Tubes_Tubes.tripod.com/tubestubestubes/index.html

http://Tubes_Tubes_Tubes.tripod.com/

----- Original Message -----
From: <w5sum@glowbugs.com>
To: <johnson@mailman.qth.net>
Sent: Tuesday, February 12, 2002 8:58 AM
Subject: [Johnson] valiant audio problems


> howdy men
> This will be somewhat long. Put on your thinking caps :)
>
> My valiant has some quirky problems with the audio. I can use an
> astatic 10DA and I get PLENTY of audio. In fact I only have to turn
> the gain up to about the 10 or 11 o'clock position to get all the
> audio I need. BUT when I use the D104 I have to turn the audio gain
> up nearly all the way and it sounds like poop.
>
> Now, this is my original Valiant I have had since I was a yonker. I
> had loaned it out three years ago and the fellow I loaned it too
> prompty traded it to another ham for a rice box! That ham traded it
> to someone else, who traded it to another ham that I happened to
> know, so I got it back by trading off my Apache for it. Somewhere
> along this path, it had its microphone chassis connector changed
> out to a CB type 4 pin plug.  When examining it, it looked like it
> had been wired up by a drunk monkey with a blow torch! I found a
> PAIR of cermet 474K resistors in parallel, in place of the 1 Meg
> Resistor that was supposed to be there ( grid input of first audio
> stage)   This pair of resistors in parallel were reading real squirrely
> with my DVM and in fact, ranged up and down from 5 Meg ohm to
> 25 megohm!!!  Anyway, put a nice Allen Bradley 1M 1% in there
> and put in a regular two pin mic connector that was supposed to be
> there. I also changed out the two .005's and the 300pf caps that
> are hooked to the mic connector ( the 300 was hooked to pin 2 of
> first audio)
>
> On the air tests this morning got me an A+ for audio when using
> the 10DA but the D104 still has to have way too much audio gain
> to 100% modulate and still sounds like crap.  This D104 is used
> daily with a Ranger and gets glowing reports so I know its good.
>
> I have changed out the 12AX7, and the 6C4 in the audio, as well
> as the 12AU7 ( the clipper circuit is bypassed)
>
> So, I can't imagine why a D104 would not have enough drive for this
> rig, or WHY it sounds so darned bad.
>
> any suggestions?
>
> thanks in advance
>
> Ronnie
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