[Boatanchors] [Swan] SWAN 250C six meter rig question

[Carl]

It also had the well deserved nickname Swan Too Drifty.

Carl
KM1H


----- Original Message ----- 
From: <N4ch at aol.com>
To: <swan at mailman.qth.net>; <boatanchors at mailman.qth.net>
Sent: Wednesday, April 14, 2010 6:55 PM
Subject: Re: [Boatanchors] [Swan] SWAN 250C six meter rig question


> Hello All,
>
> Regarding the query about the Swan 250's VFO  frequency:   The "original"
> Swan 250 had an IF at 10.7 MHz, and  was single conversion.   The 
> injection
> was low side, meaning  that for 50.0 MHz operation, the VFO injection was 
> at
> 39.3 MHz.    The VFO itself ran at one third of this frequency (subsequent
> tuned circuitry  picked off the third harmonic of the VFO itself), meaning
> that at a transceive  frequency of 50.0 MHz, the VFO itself was running on
> 13.1 MHz.    There's some info on all this in a product review of the Swan 
> 250
> in the July,  1967 issue of CQ Magazine.   There's also a similar write-up
> of the  subsequent 250-C in another CQ review; see the August, 1969 issue 
> for
> that.   Also note that in the later 250-C there was another important
> change (besides the obvious receiver front-end changes, mechanical dial
> "bandset" for the VFO, addition of the meter's receiver "S" meter 
> function,
> etc.).........the 250-C's IF got moved to 10.9 MHz instead of the original 
> 10.7.
>  This means that in the 250-C, the VFO injection is 200 KHz  lower than it
> was in the 250 (at Fo = 50.0 MHz, the injection is at 39.1 MHz,  which
> means that the VFO itself is running at 13.033333 MHz now).    ALL the 
> Swan
> tube-type rigs (350, 500, 700, the 250 series, all the  "Cygnets", etc.)
> remained single-conversion; the VFO injection was always either  above or 
> below the
> IF, with the difference always being the IF frequency  itself.
>
> 73, Herman, N4CH.
>
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