[Johnson] 250-39 TR switch.
Peter Markavage
manualman at juno.com
Fri Oct 24 11:04:15 EDT 2008
There is a simple online Electric Radio Index. Covers all the issues from
day 1 and continues to be updated every month.
http://home.wi.rr.com/n9oo/ersearch.html
With a few simple key strokes, Dennis's article pops out in the list.
Pete, wa2cwa
On Fri, 24 Oct 2008 10:38:51 -0400 "Carl" <km1h at jeremy.mv.com> writes:
> Do you remember which ER issue?
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Dennis" <radioart at charter.net>
> To: <kb2wig at twcny.rr.com>; "Roy Morgan" <k1lky at earthlink.net>
> Cc: <Johnson at mailman.qth.net>
> Sent: Friday, October 24, 2008 8:16 AM
> Subject: Re: [Johnson] 250-39 TR switch.
>
>
> > Another point of view on these TR switches....
> >
> > I have three of them in use and they work great. As long as you
> keep
> > the connection between your transmitter and the TR switch short
> the
> > suckout mentioned will be slight; its because of this issue that
> > Johnson put an RF amp in the TR switch so signals won't be
> degraded.
> > You will notice some changing of signal levels when you change the
>
> > loading on your transmitter; but thats normal. In my case I have
> my
> > CE 100V & 600L coupled with a NC-303 using a Johnson TR switch and
> I
> > have two Johnson Desk KW's using the Johnson TR switch and they do
> a
> > great job. Into a 50 ohm load they will provide you over 4kw of
> > switching protection to your receiver..... Not too bad...
> >
> > With regard to the TVI, not an issue any more with cable and
> satilite
> > but in the good old days Johnson recommenced using a Low Pass
> filter
> > with the TR switch; In those days most shacks already had a LP
> filter
> > in the antenna line, I know I did, is it wasn't ever an issue....
> >
> > I remember I wrote an article for ER (Electric Radio) magizine
> > discussing the many different TR switchs and their pros and cons.
>
> > Maybe you can get a copy....
> >
> > Ciao, Dennis, k0eoo
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