[R-390] R-388 question?

[Roy Morgan]

 Could be a "pullen mixer". Highly regarded. 

Roy Morgan
K1LKY Western Mass
K1LKY68 at gmail.com

> On Sep 23, 2022, at 7:08 PM, David Olean <k1whs at metrocast.net> wrote:
> 
> That is a common conversion of the pentagrid mixer for a dual triode mixer for lower internal noise. I believe it is documented in the 75A4 compendium that is offered by Electric Radio. I believe that it originated in a Ham Radio Magazine article in the 1970s. I did the same thing to my 75A4 and it worked great.
> 
> Dave K1WHS
> 
>> On 9/23/2022 6:59 PM, John Gedde wrote:
>> Hi folks,
>> 
>>  
>> Long time no post.  I hope I'm not crossing a line asking a R388 question, but if anyone knows the answer, it'd be this group!
>> 
>>  
>> I just acquired a Collins R388.  V102 has been changed from a 6BE6 to a 6DJ8.  It was a not a trivial change since the 6BE6 is a 7-pin tube and the 6DJ8 is 9-pins!!  Looking underneath, you can't tell it wasn't done by the factory (it wasn't.)  The workmanship of whomever made this mod is superb!
>> 
>>  
>> I have only found one reference alluding to this mod in a forum post from 1997.  The poster said he had documentation of the change so this mod must be a 'thing.'
>> 
>>  
>> Any ideas!
>> 
>>  
>> 73
>> 
>> John AD2DK
>> 
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