[Swan] SW 240 lineage questions

[Greg Mijal]

Flair up?
What happened?
Frequently the plate RF choke will toast.  You may have also heated up a
resistor under the tube socket
If you have a scope you should see around 20 - 30 v Peak to peak in the
transmit mode.
Suggest you pull out the Plate RF choke and inspect it for burns.  If you
have an inductance meter you should have at least 90 uh or so for a good
choke.
The 240 is worth saving even if it doesn't have an S meter on it.
By the way I've seen both kinds of 240's one has a very square bezel around
the freq read out, the other is slightly different.
Love those Swans.
73's
Greg
WA7LYO
Kinston NC
----- Original Message -----
From: "Rick Gouge" <rickgouge at shaw.ca>
To: <W9RAN at oneradio.net>; "Discussion of equipment manufactured by Swan"
<swan at mailman.qth.net>
Sent: Monday, November 03, 2008 9:52 PM
Subject: Re: [Swan] SW 240 lineage questions


> Robert,I also have a SW240 in beautiful condition. I was trying it on AM
> along time ago and i guess i had the drive to high and had a RF flareup in
> the finally cage. Since then i can not get full drive out of it on SSB. I
> have alot of new 6DQ5. I put a new one in and no change. I also tested all
> other tubes as well. All are good. So i think it must have something to do
> with another component in the RF cage. I have a operators manual but no
shop
> manual. I hope this makes some sense to you. I would be greatful for any
> help on this matter. Rick VE7RiK
> ----- Original Message -----
> From: "Robert Nickels" <ranickel at comcast.net>
> To: "Discussion of equipment manufactured by Swan" <swan at mailman.qth.net>
> Sent: Monday, November 03, 2008 5:09 PM
> Subject: Re: [Swan] SW 240 lineage questions
>
>
> > Bill Clarke wrote:
> >>
> >> On the PA (6DQ5) pin 3 has a 5 watt 5 ohm ceramic resistor to ground.
> >> It does not look original and is not on the diagram I have. What
> >> might the reason for this modification have been?
> > Bill, that's a hack to re-balance that leg of the series-parallel heater
> > string for use with the "dark heater" version of the 6DQ5.  RCA
introduced
> > this version of the tube in the 60s as a "running change" i.e. no change
> > in marking or designation.  However the dark heater version draws
> > substantially less current than the original 6DQ5 and thus the Swan 240
> > filaments will be really unbalanced if one is just plugged in.   I did
the
> > same thing to prove to myself that this was  the case before learning
> > about the dark heater issue and have been trying to spread the word ever
> > since.    In most applications with 6.3 volt filament wiring, the new
> > version was a plus as it required less filament current, but not for the
> > Swan 240!
> >
> > By the way, I'd recommend restoring it.  Several of us use them
routinely
> > on the Vintage Sideband Net and I like the broader sounding audio.  It
> > also puts out a heck of a signal for having only one inexpensive final
> > tube!  I also have a spare TCU remote VFO console available if anyone's
> > interested.
> >
> > 73, Bob W9RAN
> > _______________________________________________
> > Swan mailing list
> > Swan at mailman.qth.net
> > http://mailman.qth.net/mailman/listinfo/swan
>
> _______________________________________________
> Swan mailing list
> Swan at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/swan