>
>Hi Larry,
>
>What I say below is a general response to your questions, and my
>personal opinion. It doesn't mean you are wrong and I am right, just
>how I view the problem.
>
>> At 09:35 AM 6/27/00 -0400, Tom Rauch wrote:
>>
>> >Interlocks work wonders, are easier on components, and work
>> >better when working VOX or QSK.
>> Tom,
>>
>> Are you saying that you would bet your life on an interlock?
>
>No.
>
>I am saying a simple interlock is more reliable than switching the
>HV supply off and on hundreds of times a day or week, and
>expecting something won't eventually fail, and depending on
>complex external wiring to turn off HV for safety.
Amen. The turn-off component could eventually short.
>
>No matter if there is an interlock or not, I always unplug and wait. I
>always check the HV meter, and then crowbar the supply.
>
>I can't see any safety advantage when depending on a transmitter
>control line to turn off the mains power to the amplifier HV supply.
>
>As a matter of fact, I consider it a potential hazard. The operator
>might be lulled into a false sense of security... depending on
>station wiring and the rig being in a non-transmit mode to make the
>PA "safe to touch".
I can not visualize how an operator could contact the anode supply unless
numerous screws were first removed.
>
>Any PA that is accessible inside in a matter of moments without
>disabling the mains, and any operator who reaches inside without
>checking HV and crowbarring the supply are both disasters waiting
>to happen. Eventually, after enough tries, it will.
>
>> By the way, how do you troubleshoot a HV circuit? Most folks wind up
>> defeating the interlock to perform maintenance and/or repairs. Have you
>> figured out how to probe a circuit with all the covers in place?
>
>Sure. I test each component, or disconnect components to isolate
>problems and THEN put the cover back on to see if the fault clears.
>
>The only exception is when I have a cover open, and then I go to a
>breaker and turn the PA on while I am across the room. I
>absolutely never get near the PA when HV is accessible and able
>to be turned on.
>
>I have specific covers that allow me to access non-HV areas for
>certain troubleshooting, or I disable the primarys by removing the
>wiring connections at some point before trouble shooting LV
>circuits.
>
>Anyone who does otherwise is a fool, in my opinion. There is
>NEVER a reason to power up a PA and stick one's hands inside or
>connect an external meter with HV on, except a lack of
>troubleshooting skills or patience.
>
For securing optimal input swr, tuned inputs are adjusted while the
amplifier is producing suds. I do not find it difficult to keep my
fingers off of the hv. I stand on a plastic matt and place a plastic
Jesus on top of the cabinet. . Why take chances.?
later, Tom
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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