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Re: [Amps] HV connector

To: jtml@vla.com, amps@contesting.com
Subject: Re: [Amps] HV connector
From: texasrf@aol.com
Date: Wed, 13 Jan 2010 03:34:33 EST
List-post: <amps@contesting.com">mailto:amps@contesting.com>
 
SHV connectors for RG8/RG213 are available from Pasternack. SHV connectors  
are longer than MHV, offering greater safety when disconnecting. In 
addition to  the coax mounted connector, there are also chassis mounted mating 
connectors.  Like everything else they offer, it ain't cheap.
 
I used a pair of them on 4500vdc twt power supply recently and all worked  
out well. I pretested the connections at 8000vdc for leakage currents and 
there  were none.
 
The twt is mounted outside in a large wooden box along with a cooling  
blower, on the back of a 6.9m dish. Two runs of RG213 connect the twt collector 
 
and cathode to the power supply in the shack. The outside mounting allows 
use of  a very short transmission line to reduce line loss at 2.3, 3.4 and 
5.7  GHz.
 
I am using a Gigavac vacuum relay to disconnect the cathode circuit for  
standby. What a joy it was to get needed answers and recommendations from  
Gigavac. Those people really know their products and to top it all off, I  
received a huge ham discount. I spent less buying the proper relay brand new  
than messing around with unknown Ebay purchases. 
 
Like most other things, there is much more to be learned about vacuum  
relays than one might think. It is quite easy to pick the wrong relay and  
experience repeated flashovers between the contacts and coil with voltages as  
low as 4500vdc, as I learned. Flashovers like this are not your friend,  they 
will make their way through all kinds of equipment and devices in the  
shack. Don't ask how I know that. 
 
73,
Gerald K5GW
 
 
In a message dated 1/12/2010 11:52:34 P.M. Central Standard Time,  
jtml@losalamos.com writes:

SHV, MHV  all good. I thought I remember MHV being a 10 kV rating, but 
maybe its  another one. The only thing I dislike about these is that they 
are mostly  used on RG58/59 sized cables. If you want to really improve 
your HV  rating, use RG8 or one of the variants with solid polyethylene 
dielectric.  Then you may use a HN or SC connector. The HN is a heck of a  
connector.

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