1200s Bugs

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M37AU
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Posts: 5
Joined: Tue Dec 08, 2015 3:57 am

1200s Bugs

Post by M37AU »

OK, I followed Kurt's "quick" loop adjustment guide and the 1200 now seems stable in the VCO's (took a few tried to get it down pact) so apart from a thorough calibration I have most of the issues fixed (blown antenna resistor, connector cleaning etc. and getting rid of false signals on the analyser as the cables were looped around each other on the modules, re-capped the power supply and reset it to 5.1v on the 5v rail) but 3 are still bugging me.

- On the spectrum analyser I get some vertical jitter (does not happen on the oscilloscope or a high noise floor signal, only on the baseline of the analyser even with no signals or antenna connected).
- I get a BFO whistle on SSB, it was quite pronounced and changed frequency but since the VCO alignment it seems to have a constant pitch now but can be varied by programming, but not turning on the second audio oscillator).
- If I turn the test set on at the power point while the units power switch is on I get a ram error and it defaults (I have changed the ram battery), is this normal?

I figure I will have to make the TF-30 so I can do a "real" VCO alignment, do a thorough check of all connections, voltages etc. and start working my way through each module looking for aged components, this is already a great unit, I have the correct Mic, it has the tracking generator and I just bought one of Steve Dold's Generate Amplifiers (option 5 equivalent without the antenna pass relay) and it's now perfect for remote testing.
I am very lucky to have such a nice test set and once I have debugged it I am sure it will be a good reliable unit for many years, any hints or tips would be much appreciated. "Wish list items" for it would be the canvas travel bag and maybe the original rubber/spring antenna but maybe I am getting a little hopeful given the age of these units...
Thanks in advance :-)

Regards - Tony Eagling Vk7YBG
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