[Johnson] Tube Designation

[David C. Hallam]

What about the Hallicrafters HT-37?  Since it uses an almost identical
system, is the carrier balance as difficult to achieve and maintain with it?

David
KC2JD/4

> -----Original Message-----
> From: johnson-bounces at mailman.qth.net
> [mailto:johnson-bounces at mailman.qth.net]On Behalf Of Langston, Mike
> Sent: Tuesday, April 22, 2008 3:04 PM
> To: Peter Markavage
> Cc: johnson at mailman.qth.net
> Subject: RE: [Johnson] Tube Designation
>
>
> Last time I tuned a Pacemaker was 1978. I was feeding a T-bolt and
> remember that I couldn't depend on the Pacemaker meter for accurate
> carrier null. I had an output meter downstream of the T-bolt and nulled
> for minimum reading on the output meter. I don't remember what tubes
> were in it.
>
> Mike KL7CD
>
> -----Original Message-----
> From: johnson-bounces at mailman.qth.net
> [mailto:johnson-bounces at mailman.qth.net] On Behalf Of Peter Markavage
> Sent: Tuesday, April 22, 2008 12:48 PM
> To: Johnson at mailman.qth.net
> Subject: Re: [Johnson] Tube Designation
>
> I seem to remember when I had the 12AT7's in the Heath SB-10, I had to
> constantly ride the carrier null pots with each transmission. Replacing
> the tubes with 6201's and replacing the null pots with 10 turn devices
> cured that problem along with the improved carrier suppression.
>
> Pete, wa2cwa
> http://www.manualman.com
>
> On Tue, 22 Apr 2008 13:21:19 -0400 "David C. Hallam"
> <dhallam at rapidsys.com> writes:
> > Pete,
> >
> > I can't seem anything one way or the other.  Right now the Pacemaker
> > is a
> > work in progress.  When I am finished refurbishing maybe I will run
> > some
> > tests.  I can try a 12AT7, ECC-81, 6201, and any other MilSpec
> > variants I
> > can get my hands on and look the carrier and side band suppression
> > on my
> > spectrum analyzer.
> >
> > David
> > KC2JD/4
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