[Boatanchors] Fwd: Crystal Current

[D C _Mac_ Macdonald]

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Begin forwarded message:

From: D C _Mac_ Macdonald <k2gkk at hotmail.com>
Date: April 27, 2014 at 17:44:44 CDT
To: Brian Carling <bcarling at cfl.rr.com>
Subject: Re: [Boatanchors] Crystal Current

A good oscillator circuit with minimal XTAL current is a tetrode such as a 6AG7 using the screen grid as the plate in a Modified Pierce circuit!

73 - Mac, K2GKK/5 in OKC


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On Apr 27, 2014, at 17:33, "Brian Carling" <bcarling at cfl.rr.com> wrote:

That is correct. Common practice is to put a 6.3 V 60 mA lamp in series with the Crystal. A good indication of the current will be shown by the brightness of the bulb.

Best regards - Bry Carling



> On Apr 27, 2014, at 4:33 PM, "Jim Wilhite" <w5jo at brightok.net> wrote:
> 
> I am not sure what the current should be but if too much is applied you can create parasitic oscillations you don't want.
> 
> Jim
> W5JO
> 
> 
> -----Original Message----- 
> 
> The 1952 - 1962 ARRL Handbooks  recommend crystal currents be held to
> 40ma max and preferably less.
> While the FT-243 type is not mentioned specifically these were in
> widespread use at that time.   HC-6/U
> types should probably be held to something less than that....
> 
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