[R-390] replacement R390A gear clamp source

[Jim Whartenby]

Interesting document, worth reading before tearing into the R-390A
https://vk6ada.com.au/collins-r-390a-urr-ten-most-common-failures-ranked-by-community-report-frequency/
Jim
Logic is a systematic method of coming to the wrong conclusion with confidence.  Murphy 

    On Saturday, July 25, 2026 at 01:29:09 PM CDT, SCOTT Barry via R-390 <r-390 at mailman.qth.net> wrote:   

 Rats.  All this talk made me get my counter out and, today, my Collins 
PTO is running about 1.529 kc too wide (1.001529 mc end-to-end).  I will 
probably have to see if I can get that closer.

73,
Barry - N4BUQ
> Paul....
>
> Seeing that you have a Cosmos PTO, there are 2 seperate adjustments. 
> One sets the end to end 1Mc ten turn coverage, and another that sets 
> the 25kc points which is much more involved and difficult to adjust.
>
> You should do some reading about the Cosmos adjustments...
>
> 73...Jordan VE6ZT
>
> ----- Original Message ----- From: "Paul Roche" <rochep at comcast.net>
> To: "Jordan Arndt" <Outposter30 at shaw.ca>
> Cc: "Barry" <n4buq at knology.net>; "R-390 Mailing List" 
> <r-390 at mailman.qth.net>
> Sent: Saturday, July 25, 2026 9:45 AM
> Subject: Re: [R-390] replacement R390A gear clamp source
>
>
> It is a Cosmos 136-1 PTO, SN 21195 (I think that’s means it’s a pretty 
> late one).
> Sent from my iPhone
>
>> On Jul 25, 2026, at 11:23 AM, Jordan Arndt <Outposter30 at shaw.ca> wrote:
>>
>> Paul....What you're seeeing is the cover for the adjustment....the 
>> real adjustemnt is hidden behind that cover screw which you need to 
>> remove. Behind it is a small slotted brass rod that you adjust...I 
>> wouldn't try to adjust it until you're sure you have everything 
>> properly synchronized.
>>
>> What type of PTO is it...? Collins type or Cosmos type...?
>>
>> YMMV....73...Jordan VE6ZT
>
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