[R-390] Need value of R235 from a RF deck

[Patrick]

Craig, I have a signal generator that has a plug for testing crystals, it 
has never failed to tell me, with a frequency counter attached,  if a 
crystal is good or bad, if you want I can test the crystal for you.    Pat
----- Original Message ----- 
From: "Craig C. Heaton" <wd8kdg at worldnet.att.net>
To: <Flowertime01 at wmconnect.com>; <r-390 at mailman.qth.net>
Sent: Sunday, August 03, 2008 3:52 PM
Subject: RE: [R-390] Need value of R235 from a RF deck


> Roger,
>
> I don't think it was crud. When I brought the Amelco home in 2006 and
> recapped the beast, the crystal calibrator section never worked correctly.
> In trouble shooting it, I swapped crystals, the entire oven, and tried a
> crystal that someone sent me. De-Oxit was applied to the pins. Nothing is
> impossible, but dirty pins on the crystal or oven are highly unlikely. 
> Must
> of pulled it out a dozen times! Also had the original crystal pop out of 
> the
> heater as I was prying on it. Bounced on the floor a couple of times, and
> rattled ever since. Done broke it.
>
> Those that have recapped the RF section know there are two BBOD's in the
> crystal calibrator section, but are connected to the heater element of the
> oven. Kinda hard to mess things up. I looked for hours trying to find any
> passive components touching, wires rubbing, etc., before warming up the
> soldering iron.
>
> My guess it was a combination of things. There is a 1meg ohm resistor
> paralleled across a 15pF silver mica. Its value had drifted to around 
> 1.5meg
> when hot, dropping in resistance as the circuit cooled. A couple other
> resistors had increased 20% or more. Then R235 was just plain wrong, but 
> has
> no bearing on the oscillator circuit.
>
> What I don't understand is why the new crystal from International Crystal
> Manufacture doesn't work in the Amelco, but in the Motorola it functions
> just fine???????????My guess is not too many people get enough practice
> making crystals of that type, and I was sent one that is just border line.
> Just, almost, good enough to be sold for $104.00 US dollars. They made one
> and they sold it, hoping it would work.
>
> I have no way of testing what they sent, but bet there is someone that has
> the equipment and/or the experience to do so.
>
> Craig,
>
>
>
> -----Original Message-----
> From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
> On Behalf Of Flowertime01 at wmconnect.com
> Sent: Sunday, August 03, 2008 10:34 AM
> To: r-390 at mailman.qth.net
> Subject: Re: [R-390] Need value of R235 from a RF deck
>
> Craig,
>
> So are we going to write this one up as no trouble found?
>
> Just crud on pin and plug contacts and after enough parts are pulled and
> replaced, enough crud gets displaced to return the circuit to operation.
>
> Another routine R390/A problem.
>
> Roger AI4NI
>
> P.S. It sure was fun while it lasted. Maybe not for you Craig, but I'm 
> just
> looking on.   </HTML>
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