[Boatanchors] Electronic T/R Switch vs Coaxial Type

[Bob Macklin]

The Johnson T/R switch documentation on BAMA has two tubes.

One is a 6BL7 dual triode. The second is a 6X4 rectifier.

Mine is a 12AU7 dual triode and the 6X4 rectifier is in my HR-10.

Bob Macklin
K5MYJ
Kent (Seattle), Wa,
"Real Radios Glow in the Dark"

----- Original Message ----- 
From: "Carl" <km1h at jeremy.mv.com>
To: "Bob Macklin" <macklinbob at msn.com>; <boatanchors at mailman.qth.net>
Sent: Tuesday, November 04, 2008 2:15 PM
Subject: Re: [Boatanchors] Electronic T/R Switch vs Coaxial Type


> There are 2 versions of the Johnson. The early one with a single tube is
> the TVI generator, the later 2 tube version is usually OK.
>
> Use a LPF with any rig, even a BC-610; the software for balanced and
> unbalanced lines is online.
>
> Carl
> KM1H
>
>
> ----- Original Message ----- 
> From: "Bob Macklin" <macklinbob at msn.com>
> To: "rbethman" <rbethman at comcast.net>; <boatanchors at mailman.qth.net>
> Cc: "Peter Markavage" <manualman at juno.com>
> Sent: Tuesday, November 04, 2008 3:28 PM
> Subject: Re: [Boatanchors] Electronic T/R Switch vs Coaxial Type
>
>
> > Do modern solid state TVs with cable connections have the same TVI
> > problems
> > the old tube TVs did?
> >
> > I have a 10 year old Sony that gets RF OVERLOAD when I use my 2M FM
> > RICEBOX
> > that is about 2ft from it with a 19" whip on it. If I turn the TV
> > sound off
> > there is no problem with the picture. If I tune to cable channel 18 I
> > do see
> > some RF TVI but not much. CH18 is in the 2M band.
> >
> > I need to try it with the new cable DTV converter.
> >
> > Bob Macklin
> > K5MYJ
> > Kent (Seattle), Wa,
> > "Real Radios Glow in the Dark"
> >
> > ----- Original Message ----- 
> > From: "rbethman" <rbethman at comcast.net>
> > To: <boatanchors at mailman.qth.net>
> > Cc: "Peter Markavage" <manualman at juno.com>
> > Sent: Tuesday, November 04, 2008 12:02 PM
> > Subject: Re: [Boatanchors] Electronic T/R Switch vs Coaxial Type
> >
> >
> >> I, like Pete have been running a Johnson TR Switch on the output of a
> >> BC-610.  NO TVI!  I monitor the output of the BC-610 with an SM-220
> >> w/BP-8.  I also feed my receiver's IF into the SM-220.  I observe NO
> >> TVI.
> >>
> >> I believe that those getting TVI are mistakenly relating the source
> >> as
> >> the TR Switch.  I only see TVI when over modulating an Apache.
> >>
> >> Bob - N0DGN
> >>
> >> Peter Markavage wrote:
> >> > I've run a Johnson T-R switch on the Johnson Thunderbolt for years
> >> > and
> >> > not experienced any TVI related issues. I also have a Dow-Key relay
> >> > on
> >> > the back of my Apache that's been there and working since around
> > 1960/61.
> >> > The Dow-Key on the back of my Viking II has been there and running
> >> > since
> >> > 1955. These relays were some of my better investments.
> >> >
> >> > Pete, wa2cwa
> >> >
> >> >
> >> > On Tue, 4 Nov 2008 10:36:39 -0800 "BLIMPY" <blimpboy at sonic.net>
> >> > writes:
> >> >
> >> >> Biased vac tube T/R switches have bad reputation as TVI
> >> >> generators.
> >> >> Many
> >> >> in-line filters are not tolerant of impedence mis-matches
> >> >> expecially
> >> >> those
> >> >> with  reactive components.
> >> >>
> >> >> Run of the Mill Dow Key are second rate relays.. compared to
> >> >> Advance
> >> >> Coaxial
> >> >> Relays.. which are available for less money and will give no grief
> >> >> due to
> >> >> unscheduled liberation of smoke.  Some BNC commerical application
> >> >> surplus
> >> >> relays  with dc  may be contradict this generality.
> >> >>
> >> >> a vox type t/r switch might be a workable compromise, but not true
> >> >> break-in
> >> >>
> >> >> good luck
> >> >>
> >> >>
> >> >> _______________________________________________
> >> >>
> >> >>
> >> >>
> >> > _______________________________________________
> >> >
> >> >
> >>
> >> -- 
> >> Bob - NØDGN
> >>
> >> _______________________________________________
> >>
> >
> > _______________________________________________
> >
>
>