[R-390] R-390a modified IF sub-chassis

[Bill Cotter]

Gary,

The schematic you sent looks very much like the W7DI product 
detector modification that was published in Ham Radio Magazine July 
of 1974.

I have used this particular modification in two of my R-390A's. It 
works great, and does not require a panel mod. And, the IF deck can 
be interchanged into any R390A.

73 Bill N4LG


At 12:30 AM 9/28/2017, you wrote:
>Thanks to all who have responded.  I have now had the opportunity 
>to trace
>the circuit.  It appears to be  a partial implementation of the 
>Capt. Paul
>H. Lee product detector modification.  Referring to the R-390a 2K 
>manual
>description (Chapter 11, pages 31 following):
>
>
>
>1.       There are no modifications to the panel wiring, so , 
>steps 3 - 13
>are not performed;
>
>2.       Steps 15 and 16 appear to have been performed;
>
>3.       Step 17 is 10K resistor not 11K;
>
>4.       Steps 18 to 20 appear to have been performed;
>
>5.       Step 21 was not performed;
>
>6.       Step 22 appears to have been performed;
>
>7.       Steps 23 and 24 are not performed presumably per 
>suggestion of
>Eugene A. Hubbell, W7DI;
>
>8.       Step 25 appears to have been performed;
>
>9.       Step 26 is a 1,000 uF 25VDC electrolytic rather than 63VDC as
>prescribed;
>
>10.   Instead of an insulated standoff per step 27, pin 4 of RT510 
>was used;
>
>11.   Step 28 is a 27K resistor;
>
>12.   Steps 29 and 30 are not performed;
>
>13.   Step 33 (replacement tube 6BE6) is installed;
>
>
>
>The link below is my rendition of the schematic including the 
>mystery 8 pin
>part previously advised of.  Again, any suggestion as to what this
>modification accomplishes would be appreciated.
>
>
>
>https://1drv.ms/b/s!AhXaYQRsUlJ0gbZ66H5Xvz8I_og_2A
>
>
>
>73, Gary
>
>
>
>From: Roy Morgan [mailto:k1lky68 at gmail.com]
>Sent: Tuesday, September 26, 2017 3:26 PM
>To: Gary I. Biasini <gary.biasini at shaw.ca>
>Cc: r-390 at mailman.qth.net
>Subject: Re: [R-390] R-290a modified IF sub-chassis
>
>
>
>
>
>On Sep 3, 2017, at 8:17 PM, Gary I. Biasini <gary.biasini at shaw.ca
><mailto:gary.biasini at shaw.ca> > wrote:
>
>
>The URLs to pictures of the modified module are below:
>
>https://1drv.ms/i/s!AhXaYQRsUlJ0gbU1YrERkfud0axItQ
>
>https://1drv.ms/i/s!AhXaYQRsUlJ0gbU5K1--TAXeKe4ZgQ
>
>
>
>Gary,
>
>
>
>That thing with the 8 leads MIGHT be an SSB module.  Or perhaps a 
>diode quad
>product detector.
>
>
>
>Just guessing.  Never saw any such as that.
>
>
>
>
>
>Roy
>
>
>
>
>
>
>
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