[R-390] re; R211

[Craig C. Heaton]

Forgot to add the two crystals in HR202 are meant to operated at or near 75
degrees C. Some have used the 17MHz crystal from the crystal oscillator
decks, but I believe there are different specs for each.

Craig,



-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of 22hornet at gmail.com
Sent: Saturday, November 07, 2009 4:29 PM
To: R-390 at mailman.qth.net
Subject: Re: [R-390] re; R211

I always though in order to prevent frying the crystal you have to turn the

heater off. That was one of the first things I learned when I got my R390A

On Nov 7, 2009 5:21pm, Bill Hawkins <bill at iaxs.net> wrote:
> Well, you could simulate the circuit with SPICE if you had all of the

> hardware and software and knowledge required, or you could bridge the

> 82K resistor with a 10K resistor and see what happened.



> Wait - a 1952 A model? Must have been early in the A generation, no?

> Maybe things changed.



> I'd give a better answer if I had the manuals at hand, but I've been

> thinning the collection to avoid the dumpster.



> Bill Hawkins





> -----Original Message-----

> From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]

> On Behalf Of wli

> Sent: Saturday, November 07, 2009 5:51 PM

> To: R-390 at mailman.qth.net

> Subject: [R-390] re; R211



> I am in the process of going through the RF deck on my 1952 Collins R390A.

> The first thing that struck me was the chassis darkening in the

> subcompartment under HR202. As we know the heater is *on* all the time,

> cooking the Xtals. All the small components there showed the effects of  
> lots

> heat with runny wax on the micas and darkened ceramic disc bypasses.



> One strange finding was R211. There was a 82K resistor, but all the  
> manuals

> called for a 8.2K resistor. My question is: is this just an innocent  
> error?



> Thanks



> W. Li



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