Re: {Collins} 51S-1

["Stanley M Miln" <k6rmr@xxxxxxxxxxx>]

Hi Bill and fellow Collins Collctors.
In My 75S3B I found a 7543 in my Dad's Tubes from
30 Years ago. With the 7543 the PTO is SO stable.
The drift from Cold to warm-up is almost not
Noticable. The 6AU6 was not bad but that
7543 is just Great.
Also since I am using the Receive PTO on my
32S3, my Transmitter is just as stable.
                      Stan K6RMR

> The inter-electrode capacitances are often different in the "Industrial
> Strength" versions of tubes, so watch the alignment when using this kind 
> of
> a replacement.  My take on this, Collins chose the 7543 for its more 
> robust
> (and thus physically more stable - good in a PTO) construction so I would
> stick with the 7543.
>
>
> Bill Carns, N7OTQ
> Trustee K0CXX
> President, Collins Collectors Association
> Editor, Signal Magazine
> Wimberley, TX
> 512 618 2762  (Cell)
> 512 847 7010  (Home)
>
>
>
> -----Original Message-----
> From: Collins [mailto:collins-bounces+wcarns=austin.rr.com@xxxxxxxxxxxxx] 
> On
> Behalf Of Rick Poole WA1RKT
> Sent: Thursday, November 20, 2014 6:46 AM
> To: collins
> Subject: Re: {Collins} 51S-1
>
> Good morning, Steve.
>
> Per a Sylvania data sheet dated April 1960 (google "6AU6 7543"):
>
> "The Sylvania Type 7543 is designed to provide low hum, non-microphonic
> operation through the incorporation of a helical wound heater and rigid
> mounting of the internal components.  The 7543 is otherwise similar to, 
> and
> a replacement for, the Type 6AU6.".
>
> So, I'd say the 6AU6 should work fine.
>
> Rick WA1RKT
> Londonderry, NH
> Catch me on 14.300 MHz Intercon / MMSN most days
>
>
> ----- Original Message -----
> From: "Steve Wender" <tobiebw2@xxxxxxxxxxxxx>
> To: "collins" <collins@xxxxxxxxxxxxx>
> Sent: Wednesday, November 19, 2014 11:58:06 PM
> Subject: {Collins} 51S-1
>
> Hi All,
>
> I am trying to bring a 51S-1 back to life.  I have tested the tubes and
> found many showing shorts and I replaced them.  The 7543 oscillator tube 
> is
> also showing a short and I replaced it with a 6AU6.  How bad is that?  It
> seems to work.  Should I bother buying a 7543?  They don't seem too
> expensive. What are your thoughts?
>
> Thanks,
>
> Steve
> KC5WN
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