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

[Barrie Smith]

Carl:

I used a Swan 250 for a number of years.  That was not "Drift", is was an 
early, and commendable, attempt at band scanning.

73, Barrie, W7ALW

> 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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