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Old 25th May 2015, 12:44 pm   #18
G0HZU_JMR
Dekatron
 
Join Date: Sep 2010
Location: Cheltenham, Gloucestershire, UK.
Posts: 3,077
Default Re: Spectrum Analyser TR4172

I found my old notes on the mixer and the part number is DMJ4708 which also has an HP equivalent part 1906-0279 according to some sources.

I think Alpha (now renamed to Skyworks) used to make/sell the DMJ4708. There are a few US retailers selling new/old stock online but not for overseas buyers.

Patience is probably your best bet here. If you keep searching you may find one cheaply. Or maybe get someone in the US to buy one for you.

However, I'd be surprised if the mixer is dead.

Here's a couple of faults I would consider more likely than a blown up mixer.

IF1 amplifier lost bias voltage due to eroded (printed) resistor on the active bias board.
Corroded/broken connection to one of the SMA connector centres inside the IF1 module.
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