[R-390] Saturday's Line & Local Report

[Craig Heaton]

Good Morning Charles et All, 

Sometime today the IF output of both receivers are going to be checked.
Money says I'll order some new caps and see what happens. Every year for the
last couple of years I've spent a week or so going thru the Amelco searching
for the loud audio cause. If it were no audio, could be easier to find. Loud
audio, just turn down the RF gain a tweak. If the caps don't fix it, the
boombox goes back to its operating station for another year.

The AF section was checked last night again; wiring good, resistors good,
all but two caps have been replaced (C612,C601) C601 looks like a Vitamin Q,
C612 is a silver mica. J619 & J620; terminal resistance checked per Y2K. 

I'm tired of swapping modules. Where I can pick a point and check voltages,
watch the O'scope, etc; much easier. 

Several times the boombox has been mentioned here on the R-390 e-mail
reflector. C603 is the leading cause in replies. At this point, caps are
like tubes, check them in circuit. The values of all three are good to go,
leakage is very low according to the TO-6A.  If it should bypass all audio
to ground, we have a suspect.

This week hasn't been a total loss. The jumper touching that resistor wasn't
found before. I might add the positioning of the wiring harness in the
Amelco lacks a little. There are two spots where the harness sits on
mounting studs. Have to wonder how that got past a military inspection.   

Regards,
Craig 



-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of Charles Steinmetz
Sent: Saturday, January 04, 2014 10:02 PM
To: 390 list
Subject: Re: [R-390] Saturday's Line & Local Report

Craig wrote:

>As stated before; moving either the IF or the AF module from the 
>Motorola to the Amelco has had no effect on the audio.

OK, I misunderstood what you said previously.  If you can put the Motorola
IF and AF modules in the Amelco radio and the Amelco radio still has the
loud audio problem, it would appear that the problem is not in the Amelco IF
or AF modules.

I assume you have also put the Amelco IF and AF modules into the Motorola
radio, and they work fine there?  (If not, you should do that and note what
happens.)

If that is true -- the Motorola radio works fine with the Amelco IF and AF
modules, and the Amelco radio has the loud audio problem with either the
Amelco IF and AF modules or the Motorola IF and AF modules
-- then the problem does not appear to be in the Amelco IF or AF modules.

But then, it becomes very difficult to imagine where the problem could be.

Best regards,

Charles



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