[R-390] Zero adjust on R-390 receiver

[n4buq]

First R90A I had (Motorola), the clutch just wouldn't release properly.  
I had it apart a couple of times, cleaned the clutch plates, made sure 
there were no burrs, etc., but it just never worked like it should.  
Second R390A (Teledyne) I did the same thing and the clutch worked 
great.  I have heard that some of them just never did work properly.

Good luck with it,
Barry - N4BUQ

On 3/16/2013 1:34 PM, Bob Young wrote:
> Mine has never worked correctly either, it takes a lot of effort to separate the clutch and it mating surface, it does work but with effort. It is probably adjusted incorrectly and I haven't had the time to drop the front panel to check it out and see what the problem is.
>
> Bob
> KB1OKL
>
>> From: canthony15 at msn.com
>> To: w3hm at frontiernet.net; r-390 at mailman.qth.net
>> Date: Sat, 16 Mar 2013 10:46:27 -0600
>> Subject: Re: [R-390] Zero adjust on R-390 receiver
>>
>>
>> It is a mechanical clutch that connects the PTO drive to the veeder-root display. You tune in your reference signal (like WWV or whatever) and then turn on the BFO. With te BFO control centered, you tune in the signal and set the dial at the "correct" frequency. For example you tune in WWV at 5Mhz and adjust the tuning for 5.000. Then you crank the zero adjust knob clockwise enough turns to release the clutch. Then you adjust the Kilocycle tuning knob for a zero beat. The display should not move because the clutch is released. Then you unscrew (CCW) the zero adjust knob to re-engage the clutch. Now you have zero beat at a dial setting of 5.000.
>> Tony
>>
>>> From: w3hm at frontiernet.net
>>> To: r-390 at mailman.qth.net
>>> Date: Sat, 16 Mar 2013 12:32:21 -0400
>>> Subject: [R-390] Zero adjust on R-390 receiver
>>>
>>> Can anyone explain how the Zero Adjust works on an R-390 receiver.  I have
>>> two of them and the Zero Adjust doesn't work on either one.  The manual is
>>> of no help.
>>>
>>>
>>>
>>> Howard
>>>
>>> W3HM
>