[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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