Hi list, I have an i'll SPR-4. The core issue has distilled down to the receiver operating normally for 2-3 minutes then it starts "popping" and becoming distorted when the AVC line to the "S" Meter circuit is connected. Take off the line to the "S" Meter circuit, and all is well but no meter... This is all that remains to be repaired after a lightning strike 4 years ago. Before that, it was working perfectly after doing a restoration and alignment on the receiver. Serial number on this radio is 4075.
There was no antenna connected, the damage was caused by EMP from a ground hit 200' away in our pasture. So, I have had a 2nd SPR-4 (#1735) which works albiet not as well and is cosmetically not nearly in the condition the newer one has been. Where I am at now is everything is point back to an issue with on the power supply board. Had some down-time Saturday and decided to swap power supply boards. Took pictures of the 2 boards and made some drawings. Turns out the 2 boards are different and it did not work. Went to re-install the "bad" board but my pictures and drawings were no up to showing which wires attached to the correct points on the board, especially on the left hand side of the newer (#4075) board. What I should have done is removed the 2 screws holding the board and worked the wires such that I could tip it toward me to better expose all the wires and foil patterns. Have 2 versions of the SPR-4 manual but like the "C" Line, there is no diagram as to the placement/conncection of the point to point wiring. PS Board from newer, damaged receiver: http://members.cox.net/chuck.rippel/SPR4_1.jpg Older PS board from the 2nd receiver: http://members.cox.net/chuck.rippel/SPR4_2.jpg The immediate need is to be able compare another SPR-4 with a similar PS board or perhaps someone with a similar receiver will be kind photograph the foil side their PS board. Or, I can find someone to fix this one who has a track record with SPR-4's. I can fix R390A's, SP-600's and a number of other rigs but I don't much experience with an SPR-4. Once I get the power supply reinstalled and back on line, I can probably finish repairing it. If there is a upside to all this, I've learned the receiver well, have a junker for parts and can help others. Best Chuck Rippel, WA4HHG robert.c.rip...@ieee.org
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