[AMPS] Re: your mail

[Robert]

> 
> >From:        T. A. Russell, n4kg@juno.com
> >To:          Rich Measures , measures@vc.net
> >
> >Rich -
> >
> >Why not just use the 20M position on 30M?  
> >
> >Works like a champ on SB 220's.
> >
> >73, Tom
> 
>  I tried this in my SB-220, and it does work---well, sort of.  The tank Q 
> runs about 40% higher on 30m than it does on 20m.  More Q means more RF 
> circulating I burden in the bandswitch contacts.  [Circulating current is 
> roughly equal to Q*I-anode]  Since P=I^2*R, a 40% increase in I Doubles 
> the power dissipated in the contacts.  However, as the bandswitch 
> contacts heat, their RF-R increases, which further increases the power 
> dissipated in the contacts, which further increases RF-R, which........on 
> and on.  OTOH, in the SB-220 design, cooling airflow is directed at the 
> bandswitch.  
> Rich---posted to [AMPS], e-mailed to Tom---
> 
> R. L. Measures, 805-386-3734, AG6K   
> 
I haven't tried my SB220 on 30meters since 200 watts is all
we can run and my rig already produces that.  (Can we run
over 200 now on 30meters????)  I found the 4cx400 conversion
article on the mla2500 interesting since it gave full power
tests on 30meters????
-- 
73 Robert  W5AJ  w5robert@blkbox.com   

--
FAQ on WWW:               http://www.contesting.com/ampfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com