[MRCA] AN/PRR-9 for use at Hamvention

[sbjohnston at aol.com]

Since I am in Hawaii and all my military radio gear is in Wisconsin, I'm now working on a lightweight setup that can fly with me to Dayton for our 51.0 MHz operations in May.  I picked up got a PRR-9 helmet receiver and a PRT-4 transmitter is being shipped.

The PRR-9 receiver came to me with a crystal already in place for operation on 56.2 MHz (datecode 1969) so I powered it up there.  It aligned pretty easily although the second IF transformers seemed very broad.  The problem is that the receiver is pretty deaf.  Minimum discernable signal is around 30 microvolts feeding the spring terminals on the end of the PC board.  

I put a crystal in for operation on 51.0 MHz and it tuned up again with same sensitivity.

I have a vague memory of working on my other PRR-9 receivers and getting similar low-sensitivity on the bench, but when they were back in the case on the normal antenna they actually worked well hearing other stations on 51.0 MHz at Hamvention.  

Can anyone confirm my memory?   Is this normal?

I wish I could compare this receiver to one of my others, but they are 4000 miles away and I frustratingly failed to vector the XYL to their location for mailing to me.  A trench-troll must have moved them from where I remember them being stored for the past decade or two.
A side note:  I learned from this work that my new adjustable power supply is a noisy beast.  It was unusable for the PRR-9 but upon closer inspection of the output with a scope it is radiating a bunch of noise far beyond the limits allowed by the WD8DAS house rules.  Time to find or build a linear bench supply for my Hawaii shack/shop.


Steve WD8DAS   

sbjohnston at aol.com   
http://www.wd8das.net/   http://af4k-crystals.com/   
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