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Know Ur R-390A Mod1 IF strips??




 
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Author Topic: Know Ur R-390A Mod1 IF strips??  (Read 334 times)
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WBear2GCR
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Brrrr- it's cold in the shack! Fire up the BIG RIG


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« on: January 06, 2019, 12:49:17 AM »

Anyone know their IF strips for the R-390A?

This all came up while I was working on my #2 R-390A, which came in as a derelict, getting it up and running.

Have you ever seen C547 & C548 being anything other than  0.1ufd caps??
They're next to V509 and V506, the AGC circuit.

I did the easy version of the Lankford mods on my  "good" IF deck to see how it works on SSB.
Will know more tomorrow in the AM... when there are some strong SSB signals to be heard.

So, I was digging around that part of the circuit, and discovered that the #2 IF deck (Stewart-Warner) has 0.0047ufd ceramic caps
in that spot!  Not the usual "Mod 1" values, per the manual AND my other IF strip (Collins). (works ok, fine!)
They appear to be factory, as they match the others and no sign of resoldering.
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_-_- bear WB2GCR                   http://www.bearlabs.com
WD8KDG
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« Reply #1 on: January 06, 2019, 12:41:58 PM »

Dug out my old notes: On a 56 contract Motorola & 62 contract Amelco……….they were 0.1uF 200WVDC 10% paper caps (BBOD's). Replaced with some 715P Orange Drops.


Craig,
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Ham radio is now like the surprise in a box of "Cracker-Jacks". There is a new source of RFI every day.
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