[Johnson] T/R relay

[Bill Cromwell]

On 07/10/2013 06:08 PM, Carl wrote:
> Most all commercial ham amps in the 1000-1500W range use open frame 
> DPDT or 3PDT relays in the 10-13A contact range.
>
> Since the Johnson Desk is capable of 3000W PEP on AM I would suggest a 
> relay with 15-20A contacts and use a capacitor to compensate for the 
> XL bump on 10/15M.
>
> The readily available vacuum relay such as the RJ-1A or equivalent is 
> SPDT so you will either need 2 of them or a small relay on the input 
> that is fast enough. My amp uses a regular DPDT DIP relay with the 
> poles in parallel and a sequencer that allows 50 wpm QSK without hot 
> switching but I stick to 20-30 wpm of VOX CW and SSB and it has held 
> up since 1986.
>
> Perhaps the simplest approach is the Johnson 250-39 Electronis T/R 
> switch which is rated to 4000W PEP. I havent run mine beyond 2000W PEP 
> on AM and its none the worse for wear.
>
> Carl
> KM1H
Gosh Carl,

I have one of those 250-39 gizmos and it works well with my Johnson 
Ranger. I have a PDF copy of the manual but I must have not been paying 
attention. I had no idea It would handle that much power! I looked again 
and it's right there in black and white - jumped right off the page at 
me. I think it's perfectly safe with my Ranger.

Thanks for pointing that out.

73,

Bill  KU8H