[Johnson] Electronic TR Switches

[manualman at juno.com]

I have two Johnson electronic T-R switches. Several years ago I swept
both of them and gain varied from less then zero to about 6db from
roughly 2 MHz to 30 MHz. Gain dropped rapidly above 20 MHz. On both 160
and 10 meters, the T-R switch acted as an attenuator on receive.
Although, even given their frequency limitations, they do work.

Pete, wa2cwa
www.manualman.com

On Fri, 25 Jul 2014 09:12:23 -0400 Bill Cromwell <wrcromwell at gmail.com>
writes:
> Hi David,
> 
> I have used and will use again the electronic switching for full 
> breakin 
> CW. I have Johnson electronic T-R switch and two homebrewed units. 
> Overcoming the problems you named are not so very difficult. But - 
> if 
> you are not going to use full breaking QSK you'll find the relay 
> much 
> simpler and useable with just about any combination of TX/RX without 
> any 
> mods to any of them.
> 
> 73,
> 
> Bill  KU8H
> 
> 
> On 07/25/2014 08:34 AM, David C. Hallam wrote:
> > I am revising the antenna feed line of my Invader 2000 to be able 
> to 
> > switch between low and high power as desired with a B&W two 
> position 
> > coax switch.  I was thinking about replacing the Dow Key relay 
> with a 
> > B&W 381-C electronic switch.  After reading back through comments 
> on 
> > various reflectors concerning electronic TR switches, this might 
> not a 
> > good idea.  Things like harmonic generation in the switch and 
> > increased receiver noise floor are cited.  I do have a couple of 
> low 
> > pass filters.  I get the impression that unless you work full 
> break-in 
> > CW (which I don't), it might be a better idea to stick with the 
> Dow 
> > Key relay.
> >
> > What might be comments on this.
> >
> > David
> > KW4DH