GPR-10 Receiver Page

This receiver was built in the late 70's and appears never to have been a TMC product.  It uses some of the modules that later made up the DDR-10, including the very elaborate RF tuner, and various plug-in modules from the HFR-4 and MSR-10.  The gallery below shows photos that were in the TMC photo stash:

684.2-2	684.2-1	684.2-2	685.2-2
6710.22-2.  This photo is marked "GPR-10 prototype.. obs. Hist. ref. only"	Marked "GPR-10 Obs.--do not use--ref. only"	685.2-1.  This receiver has an alternative set of meters and a slightly different display.  Note the type badge--late type immediately below the display.

This very handsome receiver clearly never made it into production and never became a product.  A reasonable assumption might be that all of the prototypes were destroyed or lost.  Imagine my surprise when I heard from a TMC collector who actually had one of these radios!  His GPR-10 is probably the rarest TMC rig in existence.

I was so curious about this radio that I arranged to pay its owner a visit.  I was expecting to see a rare, but unworkable radio, given the remarks I had heard from Neil and other TMC-ers about the problems with the GPR-10.  However, when I arrived at the owner's QTH I was astonished to find the radio sitting on the kitchen table working, receiving SSB transmissions on the 20m ham band! 

The current owner of this (probably the only) GPR-10 obtained the radio from someone in West Virginia.  I have no way of tracking this person down, but a reasonable guess is that he was a former TMC employee who somehow ended up carting this prototype out of the factory.  The current owner turns out to be a highly skilled restorer..  he had to rebuild the crystal filters in the radio (a formidable job) and do a bunch of other reverse engineering and repairs.  He is working from partial schematics, mostly from DDR-10 manuals.  That he has managed to restore this rig to full operation is a great tribute to his skill and persistence.  The rig is definitely in good hands..  Below are photos of the radio:

Front view.  Radio is working, and very well indeed!	Overall view.	Rear view.  Not sure if the fan is original or not.	Top view showing the top of the RF tuner assembly (below) and various plug-in modules (above).
Mechanical bits and components of the RF tuner.	Another view of the tuner.	Bottom view of radio.	Bottom view from rear of radio.
Top view showing module getting removed.	This module is (if memory serves) one of the IF filter modules.	And this is the inside of the filter module shown to the right.