[R-390] Dumb Mechanical Alignment question

Thu Jul 16 11:43:41 EDT 2026

Paul, Barry:
It's the alignment...
Paul cannot know if it was properly aligned before.
IF the position of the cams is dead-on correct at 07+000 NOW, it is possible that it was "off" before.
The RF deck alignment is a long and tedious process, but it cannot give proper results if the mechanical part is/was "off", even slightly.
The global "play" around the theorical center adjustment frequency (when it is properly adjusted) is not more than about 50kHz wide, so it is easy to be "off adjustment" on any band.
If the BCB band works OK, it is already good: the 17MHz oscillator is working !
But even with the global tuning completely "off", it is really hard to not receive a 50kW AM station...

73, Jacques, VE2JFE in Montreal

-----Message d'origine-----
De : r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> De la part de Barry via R-390
Envoyé : 16 juillet 2026 11:23
À : Barry <n4buq at knology.net>
Cc : R-390 Mailing List <r-390 at mailman.qth.net>
Objet : Re: [R-390] Dumb Mechanical Alignment question

It occurred to me that it's apparenty working on TWO bands.  It could still be the oscillators.  Can you hear the calibrator on any of the other bands?

Barry - N4BUQ

> Very good!  If it's working on one band (BCB), then it likely is not 
> the PTO.  I think I'd tend to check the crystal oscillator(s).
> 
> 73,
> Barry - N4BUQ
> 
>> Got her all back together. The good news is it picks up my super loud 
>> local AM stations about where they should be on the dial! The bad 
>> news is that’s basically the  ONLY stations it gets!!! Seems to have lost all sensitivity.
>> I’ll work on it; I doubt it’s the RF deck since stations come in at 
>> 950 and
>> 1260 and 1500 kc as they “should”. Will check PTO and tubes.
>> Sent from my iPhone
>> 
>>> On Jul 16, 2026, at 7:27 AM, Paul Roche <rochep at comcast.net> wrote:
>>> 
>>> Thanks so much, I might get it back together today and will give it a shot!
>>> Sent from my iPhone
>>> 
>>>> On Jul 15, 2026, at 10:50 PM, Jacques Fortin <jacques.f at videotron.ca> wrote:
>>>> 
>>>> Hi Paul,
>>>> 
>>>> When the counters are at 07+000 the PTO output have to be at 2.455 Mhz.
>>>> The PTO output change "in reverse" relating to the tuned frequency: 
>>>> if the shaft is turned clockwise, the output frequency decreases, 
>>>> if it is turned counter-clockwise, the output frequency increases.
>>>> 
>>>> 73, Jacques, VE2JFE in Montreal
>>>> 
>>>> -----Message d'origine-----
>>>> De : r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> 
>>>> De la part de Barry via R-390 Envoyé : 15 juillet 2026 22:13 À : 
>>>> PAUL ROCHE <rochep at comcast.net> Cc : R-390 Mailing List 
>>>> <r-390 at mailman.qth.net> Objet : Re: [R-390] Dumb Mechanical 
>>>> Alignment question
>>>> 
>>>> Since the PTO tunes from 3455kc down to 2455kc, you should be able 
>>>> to hear it on a general coverage receiver with a BFO.  Be aware 
>>>> that the PTO shouldn't be made to travel very much past those two frequencies.
>>>> 
>>>> Good luck with it.  It sounds like you're almost there!
>>>> 
>>>> Barry - N4BUQ
>>>> 
>>>>> I was home today with Strep throat so decided to just set it to 
>>>>> 7+000 and remove all gears , using fishing line/hemostats and tape 
>>>>> to keep every cam in position, and the re-assembled. All seems 
>>>>> good. I dread put RF deco back into the radio only to have to take 
>>>>> it out again, but it has to go in at some point.
>>>>> Have replaced bumblebee caps.
>>>>> 
>>>>> Once it is in how do I confirm all is working properly with my PTO?
>>>>> Listen to the PTO with a portable shortwave receiver?
>>>>> 
>>>>> Tightening those clamps is scary since I got this with two broken ones.
>>>>> Sent from my iPhone
>>>>> 
>>>>>>> On Jul 15, 2026, at 8:44 AM, Paul Roche <rochep at comcast.net> wrote:
>>>>>> 
>>>>>> OR now that everything is set to 7+000 do I just carefully 
>>>>>> remove gears, try to to move KHZ or MHZ shaft, and re-assemble 
>>>>>> with gears in correct positions? That might be easiest. 
>>>>>> Bandswitch and Geneva gears are at
>>>>>> 7+000 right now.
>>>>>> Sent from my iPhone
>>>>>> 
>>>>>>> On Jul 14, 2026, at 8:42 PM, PAUL ROCHE via R-390 <r-390 at mailman.qth.net> wrote:
>>>>>>> 
>>>>>>> Now have my detent spring (thanks to Don) and time to get all 
>>>>>>> set for 7.000+. I can pull up all the cams with a tool EXCEPT 
>>>>>>> the second cam from the left, it does not have a clamp. How do 
>>>>>>> I set it up so it is at the line when I am at 7.000+? Do I just 
>>>>>>> leave everthing as it is now (at 7.000), remove gears till I 
>>>>>>> can get at it, and then rotate IT to the line and carefully 
>>>>>>> re-assemble gears and cams? I am afraid if I do this and go 
>>>>>>> back to full CCW it will NOT stay where I want it when I am finally up to 7.000+.
>>>>>>> 
>>>>>>> Am I missing something obvious? I could set all cams to the 
>>>>>>> marks and the counter to 7.000+ and bandswitch correct but then 
>>>>>>> my 10 turn stop on MHZ knob would be off.
>>>>>>> 
>>>>>>> Paul
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