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[AMPS] Switches

To: <amps@contesting.com>
Subject: [AMPS] Switches
From: W8JI@contesting.com (Tom Rauch)
Date: Wed, 11 Oct 2000 17:06:20 -0400
I'm looking at various switches for an HF PA. What's the highest 
anode voltage the model 80 and 86? Anyone know what switch 
type number Alpha used in the higher anode voltage amplifiers? 

Here's what I've found on sample switches.

Measuring voltage breakdown of a modified JV-9000 series 
compared to RSC (multitech) samples of the model 80 and 86:

9000

contact to contact                              7.8
open contact to rotor                   11.7
open contact to adjacent rotor  6.3
rotor to shaft                                  9

80

contact to contact                              7.6
contact to rotor                                        6.1
open contact to adjacent rotor  6
rotor to shaft                                  8

86

contact to contact                              9.85
contact to rotor                                        6.8
open contact to adjacent rotor  6.8
rotor to shaft                                  10.8

It looks like the model 80 is ruled out because it has less voltage 
breakdown than the 9000 series, and voltage is the primary failure 
mode of switches.

The bulk of voltage appears from the ten meter contact to the rotor, 
where peak voltage exceeds the voltage applied to the tank 
because the input and output are almost out-of-phase when the 
load is open. I have to watch the contact to rotor or open contact to 
adjacent rotor the most, since that is the spot where maximum 
voltage can appear.

Between the 86 and the 9000,  I'll lose 1 kV of breakdown in the 
best case situation if I use a 86. I'll gain a lot of current handling 
with the 86, but that is not often a problem. I'm torn here. Does 
anyone know of a reasonable priced switch that handles more 
voltage? Anything bigger than the 86 isn't feasible cost-wise, since 
it is almost three times the price of the 9000.



73, Tom W8JI
w8ji@contesting.com

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