[Swan] SWAN 250C six meter rig question

[Jeramy Thibodeaux]

Something else I would like to add to Herman's post is that if you are not 
using the external VFO then you need to ensure that you have the accessory 
jumper plug installed.  This plug jumpers pin 1 to pin 8 on the accessory 
socket and ensures that the VFO signal makes it to the rest of the mixers 
and amps for proper transmit/receive.

73
Jeramy
kg4azt

----- 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: [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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