[R-390] 17.000 Mhz Crystal

[Bob Camp]

Hi

The heaters on the main crystal deck are not critical to performance at normal temperatures. The crystals will move 10's of ppm as they heat up. That's < 1 KHz at 30 MHz. The heaters are there in case you happen to be operating the radio at -40 F….

Bob

On May 13, 2013, at 11:18 PM, Norman Ryan <nnryann at yahoo.com> wrote:

> Hi, all,
> 
> I wonder if oven temperature is critical to crystal performance (other than limiting frequency drift).  Oftentimes a heater will fail due to corroded leads from the pin(s) to the heater element.
> 
> Is a working oven heater element an issue, given that most of our receivers are operated in generally stable ambient temperatures?  That is, would a failed heater element put a harelip on performance?
> 
> 73 de Norman, KG4SWM
> 
> 
> --- On Mon, 5/13/13, Roger Ruszkowski <flowertime01 at wmconnect.com> wrote:
> 
>> From: Roger Ruszkowski <flowertime01 at wmconnect.com>
>> Subject: Re: [R-390] 17.000 Mhz Crystal
>> To: R-390 at mailman.qth.net
>> Date: Monday, May 13, 2013, 9:05 PM
>> 
>> Gordon,
>> 
>> Yes you can swap the first mixer crystal with the second
>> mixer crystal 
>> just to check that the second mixer crystal is the problem
>> on
>> 14 and 31.
>> 
>> I have no idea how far off frequency it will be.
>> 
>> You may get lucky and it will work very well.
>> 
>> Back when we just had two many parts on hand and
>> never had to resort to this level of maintenance.
>> 
>> I always had 400 plus receivers in the building and more
>> than
>> one of them was not in exact use a any given hour. I could
>> always find an exact part to swap. 
>> 
>> As this is a rebuild, look for some crud in a socket pin.
>> a shorted trim cap wire. But first just plug in a different
>> crystal.
>> 
>> Thunk the crystal a time of two as it may have crud inside.
>> 
>> Crystals do go bad and is the most likely problem.
>> 
>> Just resetting the crystal a time of two in the socket may
>> clean
>> up the contacts.
>> 
>> If you have a scope, you do not need an exact crystal.
>> 
>> Swap any crystal within reason 15 - 20 Mhz into the
>> socket and look for a signal with the scope on the RF
>> mixer tube pin. 
>> 
>> Roger AI4NI
>> 
>> 
>> 
>> 
>> 
>> Well, I finally have my R-390A re-assembled.
>> I turned it on today and so far looks and works great EXCEPT
>> for 14 and 
>> 31 Mhz.
>> After some quick checks, it appears my 17.000 Mhz (Y-412)
>> Crystal is bad.
>> Does anyone have one to sell ?
>> 
>> Thanks,
>> Gordon
>> N6WK
>> 
>> 
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>> 
>> 
>> 
>> -----Original Message-----
>> From: Gordon <gordon at n6wk.com>
>> To: R-390 <R-390 at mailman.qth.net>
>> Sent: Sun, May 12, 2013 7:54 pm
>> Subject: [R-390] 17.000 Mhz Crystal
>> 
>> 
>> Well, I finally have my R-390A re-assembled.
>> I turned it on today and so far looks and works great EXCEPT
>> for 14 and 
>> 31 Mhz.
>> After some quick checks, it appears my 17.000 Mhz (Y-412)
>> Crystal is bad.
>> Does anyone have one to sell ?
>> 
>> Thanks,
>> Gordon
>> N6WK
>> 
>> 
>> ______________________________________________________________
>> R-390 mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/r-390
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:R-390 at mailman.qth.net
>> 
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> 
>> 
>> ______________________________________________________________
>> R-390 mailing list
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>> Help: http://mailman.qth.net/mmfaq.htm
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>> 
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>> Please help support this email list: http://www.qsl.net/donate.html
>> 
> ______________________________________________________________
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> 
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