[Hallicrafters] Hallicrafters SM40 S-meter for the S40/A

[Mike Everette]

Julian,

If I read your post correctly, the resistors you're looking at in the receiver should be indeed proper.  The use of "M" for "K" in older schematics and parts lists was quite common; so a 24M resistor is actually 24,000 ohms or 24K in modern terms.

BUT:  Are the resistor values correct as measured with an ohmmeter?

Sounds like you have a resistor "off" somewhere in the meter bridge circuit; or you have an AVC-controlled stage drawing way too much current perhaps due to a bad resistor somewhere else.

73

Mike
W4DSE


--- On Sun, 11/20/11, Julian Bunn <Julian.Bunn at caltech.edu> wrote:

> From: Julian Bunn <Julian.Bunn at caltech.edu>
> Subject: [Hallicrafters] Hallicrafters SM40 S-meter for the S40/A
> To: Hallicrafters at mailman.qth.net
> Date: Sunday, November 20, 2011, 5:30 PM
> It being a rainy day I decided to get
> out my S40A and SM40 external S-meter and see if
> I could understand why the S-meter wasn't behaving as it
> should (needle always pegged
> to the right hand side of the scale).
> 
> I opened the SM40 up and found that instead of the three
> resistors (one variable)
> inside being 24M/10M/20M as per the circuit diagram, they
> are 24k/10k/20k instead.
> 
> Does anyone know if the circuit diagram (e.g. at http://bama.edebris.com/manuals/hallicra/sm40/)
> is wrong, or if my unit has the wrong resistors?
> 
> I can't see that it would matter much as the resistor chain
> is just a potential
> divider for B+, but maybe I'm mistaken?
> 
> Thanks!
> Julian
> 
> 
> -----Inline Attachment Follows-----
> 
> ______________________________________________________________
> Hallicrafters mailing list
> Home: http://mailman.qth.net/mailman/listinfo/hallicrafters
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Hallicrafters at mailman.qth.net
> 
> List Administrator: Duane Fischer, W8DBF
> ** For Assistance: dfischer at usol.com ** 
> 
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html