[GreenKeys] Dovetron Repair

[B. Smith]

A handy device is an op amp tester.  The one pictured came as a kit. It 
has a zero insertion force socket which is kind of neat.
Note that some op amp brands out perform others and I think that is 
mentioned in the Dovetron manual.
See attached.

Polar relays can be tested and adjusted.
http://k4che.com/Polar%20Relay%20Test/Polar%20Relay%20Testing.htm

K4CHE

On 2/12/2024 8:25 PM, Tom Hunter wrote:
> John Spigel,
>
> I have recently repaired two 1000Ts and am fighting with an MPC 1000. 
> All Doverons are basically similiar.
> The mark and Space tuning, the filters, etc are all the same.
>
> It helps to have a decent oscilloscope and a handful of 741 opamps for 
> substitution.
>
> I believe you said you have a 1000T. If you want to key a loop with it 
> you must use a polar relay (255A - tricky to adjust) or if you can 
> find one, a 314A which needs no adjustment. I connect my relay to the 
> +/- 12 volt output and use it  to key an external 60-mil loop. The 
> 'scope will show you if you the polar outputs are working before you 
> connect the relay.after that the relay chatter will prove they are 
> working.
>
> My problem with my MPC 1000 is that the signal loss light flickers on 
> space. When signal loss is activated it ties the unit up in mark hold. 
> Mine works fine on the bench but acts up in the rack. I am stumped!
>
>
> Tom   N3CRK
>
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