[TenTec] Restoring 1320 QRP

[dw]

Hi Michael,
I few thoughts of the top of my head.
First I hesitate to probe unless with a high impedance lead.
I may put a 50k resistor on the lead just in case, to check pin
voltages.
For dc bias, I look first for the output voltage.
If it approximates vcc, I look to confirm that the plus input is
slightly higher than the negative.
I would look at the resistive biasing and see if the voltages look like
they should.   I have ever pulled a chip by cutting off the pins as
close to the body as possible.
Then with a length of pin, I can heat it up good with and iron and pull
it out.
Then suck the rest, replace with socket.
Hope this helps
Duane


On Thu, 25 Jan 2007 10:48:31 -0000, "MICHAEL CLARKE"
<michaelclarke719 at btinternet.com> said:
> Hi All
> Help
> I was given as a present a sick TT 1320 transreceiver,
> and told that it was damaged by battery connected reverse polarity.
> After replacing howling LM386 and rewinding VFO coil.
> The RX now works, about 14.000 to 14.075 MHz,  but seems deaf.
> To increase AF signal, I am considering
> 1 Remove C42 to disable feed from half - LM358 to AGC
> 2 Short across R6 to allow full AF into LM386
> I am suspicious of the AF amplifier,  one half of a dual LM358
> But reluctant to take it out  - plated through holes make de-soldering
> near 
> impossible.
> How best might I test the LM385 in-circuit?
> Comment and advice please - many thanks
> 73
> Michael
> Mi5mtc
> 
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-- 
  dw
  dw at sover.net