Saturday, 6 July 2013

Marconi Cheesed

Bollocks! Thats the only word I can think to describe this. I went into the workshop this afternoon to show Sam the transverters receive chain working, switched on the Marconi 2955B and was greeted by a screen full of random ASCII characters. So, thats my one and only signal generator U/S. Ive found only one reference to a fault on these that causes the display to mess up, and that suggests the crystal oven 10MHz frequency standard has failed. Thats almost certainly an obsolete part. Its also mounted on the same board as the EHT circuits for the CRT, so im really not looking forward to trying to find a way of getting the scope on it.

But, until thats fixed, or I get another signal generator, im rather stumped on quite a few projects. 4m especially is not an easy band to try and work with off-air signals either.

Red Rose QRP festival tomorrow. I put a bit on the charity entrance fee auction, and ended up winning it! So ive already got my entrance fee and dinner paid for, albeit at a bit more than it would have cost on the door! Just need to take something tomorrow to prove it was me who won! Ive a small list of things to get, but generally just looking for a few bargains. Wonder if there will be a scrap 2955B...

1 comment:

sdspig said...

hi martin the trimmer cap usually fails in the 2955 ocxo module
causing the random characters i usually replace with a modern sealed can type
available for about £20 from a chap in china
i build a daughter board on a pice of vero
its a 5 volt device so the 12v feed to the ocxo is ignored
and short out the 5v feed resistor to the ocxo
all the best
steve from cornwall