2nd response to this...
Sinisa,
I had to dig deep down in my memory because it was some 35 years ago when I
was studying this stuff...
Actually Sinisa, what you just describe is called "IF Shift", not
"Passband Tuning".
These are similar, but not the same.
"IF Shift" moves the entire passband of a single filter, whereas "Passband
Tuning" moves the relative position of two filters. PBT is superior.
I still maintain that PBT canNOT be accomplished with a single IF.
I'm fairly certain of this, but not quite 100% certain, however that's the
way I remember it from my schooling long ago.
So if the TR-30A claims PBT and single IF, it is technically wrong.
Then they should re-label that knob "IFS".
For the record, IFS is a lot better than having nothing at all.
It's just not as good as PBT.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of shristov
Sent: Wednesday, October 29, 2014 7:34 AM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] repairs
Rick - DJ0IP / NJ0IP < <mailto:Rick@DJ0IP.de> Rick@DJ0IP.de> wrote:
> Could someone here please explain to me (technically) how PBT can work
> with single conversion?
PBT (with constant filter bandwidth) is easily done with single conversion
and single filter.
Just vary VFO and BFO frequencies simultaneosly to keep the resulting
carrier frequency unchanged.
73,
Sinisa YT1NT
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