[TenTec] Corsair I refurb project

[Bill ACITO, W1PA]

Thanks Al.  Yeah, I thought of that. At the risk of 
overthinking this:
- no ALC light at all
- zero output (both finals gone?)
- zero additional current (finals are not shorted?)
- both open? maybe the bias circuit is gone?  shorted but 
took out the meter shunt?

Anyway, I am going to gently separate the PA module and take 
some measurements and
see where we are before I go out and buy a new pair (it 
appears that RF Parts has the originals in stock)

Bill W1PA

-----Original Message----- 
From: Al Gulseth
Sent: Monday, October 26, 2015 12:23 PM
To: tentec at contesting.com
Cc: Bill ACITO, W1PA
Subject: Re: [TenTec] Corsair I refurb project

Maybe not very likely, but perhaps check the 0.015 ohm 
current shunt resistor
to make sure it's not open or that there's not a bad solder 
joint on the
board? I.e. make sure there's power to the finals first 
before going further.

73, Al

On Mon October 26 2015 9:54:09 am Bill ACITO, W1PA wrote:
> Number 1 is fixed.  As pointed out/suggested – loose 
> crystals.  I should
> have know this from my Omni-A/D/C experience.
>
> >>No RX 160 and 80: freq counter bounces around on  0.180 
> >>to 0.190 Mhz on
> >> these bands. I assume I should be looking at the wafer 
> >> switches and
> >> oscillators? All other bands are fine on RX.
>
> Now on to #2:
> On transmit I see no power, and no current draw.
> What’s the best way to diagnose the PA module?  Voltage 
> checks on the
> transistors themselves? Check the bias circuit? Should I 
> just replace all
> four?
> Has anyone successfully substituted for the MRF-458’s, and 
> if so, what did
> you use? Do any other rigs use the same PA module (80565) 
> that I can swap
> with?  the 561 Corsair II?
>
> >>No power out on TX -- zero.  Scope says I have good 
> >>output from the
> >>low-level driver board, which changes with the drive 
> >>control. Do the
> >> finals fail open? Do they both go together?
> >>Any easy way to check if it's the drivers or the actual 
> >>finals in the PA
> >> module? I also read that there was a common T/R diode 
> >> fail that impacted
> >> ALC? What were the symptoms of this fail?
>
> Bill W1PA
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