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Re: [Amps] SHV Connectors and B-

To: <amps@contesting.com>
Subject: Re: [Amps] SHV Connectors and B-
From: "Paul Christensen" <w9ac@arrl.net>
Date: Thu, 13 Mar 2014 09:01:46 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
"Over the past several years I have been recommending 5-pin XLR
connectors between the amplifier controller (assumed to be part of the
RF deck) and a remote HV PSU. The aim is to keep the HV-minus, control
and ground connections all together, so that the HV PSU cannot be
enabled separately without that connector plugged in."

XLR connectors are excellent for their electrical and mechanical reliability. In my case, I'm thinking of using two connectors between the amp and PS. The first will pass B+ through a chassis SHV connector. The second must pass 240V to the HV transformer as well as relay control for the HV Lo/Hi setting. In looking at suitable connectors, I'm leaning toward a 20A 8-pin Cinch-Jones or possibly a Mil-Type ITT/Canon/Amphenol multi-pin connector. A female chassis connector would be installed on the PS, and a recessed male chassis connector placed on the RF deck. With 8-pins, I can double-up on 240V and ground wiring. In doing so, an accidental pull of that plug will kill the AC primary and B+ would bleed down in several seconds. I could see placing the B- to chassis diode at the PS as well as leaving the existing diode inside the RF deck.

Since the PS will not have its own AC power plug, I would be depending on the double-ground pass through the Cinch-Jones connector. I can add a ground bolt to the PS chassis, but I want to ensure safe operation without having to depend on that bolt. The ground pass-through seems adequate to me. Anyone see other issues?

One issue I'm wrestling with is the the base design of the PS cabinet. I'm leaning toward designing my own cover panels in software but the Dahl 2A CCS transformer weighs 86 lbs. I can order cut steel plates or just stack two steel relay rack panels to help support the transformer weight. Maybe Jim and/or Vic can chime in on this. 2A is overkill and I'll inquire if they can drop the weight down by custom winding it with a 1.2A or maybe 1.5A spec at 3200V. That will result in about 4.3KV on the plate.

Just got the quote back from Hoyt on the 250-degree panel meters. Ready for this? USD $400 ea. x 4 = $1600 for the set. Pricing includes custom legends and back-illumination. Simpson wasn't much better at $325 ea. They do look cool though...

Paul, W9AC
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