[Swan] Re: [Swan-Net] AC hum in the speaker...

Fri, 14 Jun 2002 16:20:26 -0400

Not sure if this is a ongoing problem or a recent one as I just bought the
radio June 2,2002 at a hamfest. The hum comes on slowly right after turning
it on, slowly gets louder, and then drops back down to a low level after
radio has been on for a while (30-45minutes) but never goes away.

Also don't know how long the radio had been in storage before I bought it,
but will check over the solder connections to the JONES plugs as well as I
was going to use some contact cleaner on the rotary switches as the RX
setting switch make a lot of noise when switched.

Will try to see if the local tech guru can test the caps for me as he has
the radio right now setting up the TV2B for a 6meter IF.

Hopefully???  I will be running the 250 & TV2B for next weekends Field Day
station so look for W8MWA from West Virginia and let me know how we sound!!!

Jacob Tennant  K8JWT
----- Original Message -----
From: <[email protected]>
To: <[email protected]>
Sent: Friday, June 14, 2002 3:19 PM
Subject: Re: [Swan-Net] AC hum in the speaker...

> Jacob, sometimes one gets hum when the Jones plug (12 pin) on the end of
> the power cable from the power supply gets dirty. Disconnect and really
> clean the male plug tips sticking out of the xcvr. Put a little deoxit
> or pro gold or similar contact cleaner on it, also squirt some contact
> cleaner into the female 12 pin on end of power cord. If this connection
> is still not firm, you may need to twist the male tips slightly to
> improve contact.
> I would check the caps in the power supply with a cap tester that can
> show if they are leaking or not. The spec books I have access to say
> that for 100 mmf caps leakage of up to 1 mil or so at working voltage is
> acceptable. I wouldn't automatically replace ps caps unless I had tested
> them.
> It would be useful to know if this hum is a recent development or has
> it always been there? Has the rig sat unused for a long time? Such info
> is useful to figger it out.
> Sometimes solder connections in the male or female 12 pin plug need to
> be restored. Or there are other possibilities.
> The Swan rigs are super, and can be maintained by the user. I think you
> are smart to keep it. I recently took one out in the boonies, had only
> minumum equipment, but because of the good output section on the PA, I
> was able to load up a crude antenna with no separate antenna tuner box.
> Made some QSOs with it too.
>
> Jacob Tennant wrote:
> >
> > I am getting a annoying AC hum in my speaker of my 117XC power supply
for my
> > Swan 250?  I have been told that this is one or more of the capacitors
in
> > the power supply leaking?
> >
> > >From the schematics the only ones that appear to possibly be the
culprits
> > are the big paper covered caps. that are the various 100MF/350WV and
> > 150MF/150WV ones.
> >
> > Am I close to being correct or have I missed some other caps that I
should
> > replace?
> >
> > Was going to maybe sell this setup on eBay, BUT have decided not to as
for
> > some reason I just can't let this old rig go... it has kind of grown on
me,
> > so I am going to fix it up some to make it last for another 30-35 years
as
> > from the serial number it was made about the same time I was born (mid
> > 1966).
> >
> > Jacob Tennant  K8JWT
> >
>
> --
> Kenneth L Ketner
> Paul Whitfield Horn Professor
> Institute for Studies in Pragmaticism
> Texas Tech University
> Lubbock, TX 79409-0002
> 806 742 3128
> Office email: [email protected]
> Home email: [email protected]
> Office website: http://www.pragmaticism.net
> Personal website: http://www.wyttynys.net
>
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