[Boatanchors] Electronic T/R Switch vs Coaxial Type

[Carl]

Im not counting the rectifier and I should have said stages.

The early Johnson had one RF stage and the 250-39 had two using a hefty 
6BL7.

Carl
KM1H
----- Original Message ----- 
From: "Bob Macklin" <macklinbob at msn.com>
To: "Carl" <km1h at jeremy.mv.com>; <boatanchors at mailman.qth.net>
Sent: Tuesday, November 04, 2008 6:13 PM
Subject: Re: [Boatanchors] Electronic T/R Switch vs Coaxial Type


> 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
>> >>
>> >> _______________________________________________
>> >>
>> >
>> > _______________________________________________
>> >
>>
>>
>
>