[AMPS] Flying Rails and other
km1h @ juno.com
km1h@juno.com
Sun, 07 Sep 1997 14:11:07 EDT
On Sun, 7 Sep 1997 11:30:08 +0000 w8jitom@postoffice.worldnet.att.net
writes:
>> From: km1h@juno.com (km1h @ juno.com)
>> Subject: Re: [AMPS] two questions
>> Date: Sat, 6 Sep 97 20:34:53 +0000
>
>> tubes Ian. My primary concern is with HV insulation breakdown. A
>properly
>> spec'd 5V 30A fil xfmr is designed with 5KV or more insulation and
>will
>> not place the HV out on the AC mains in case of a catastrophic tube
>> failure, etc.
>
>Hmmmm.
>
>So it's OK to float the grids via some fusible resistance, but you
>still worry about 5 kV on the filament winding?
Yep. Until someone devises a fool proof protection circuit.
>Maybe if you grounded the grids, the filament wouldn't fly up to
>the positive anode supply rail voltage? The grid would be "in the
>way" of the arc.
And take out the tube, suppressor, plate choke which is the common
destruction path in the AL-82. Throw in a bandswitch too if the arc was
due to an "event" in the tank circuit.
I have yet to hear of your assumed flying rail scenario. This must also
include the thousands of 30L1's out there that mysteriously caused the
premature destruction of KWM2A's with nary a service bulletin published.
Actually this sounds like a case for OSHA. Keeping us poor hams from
frying ourselves and our riceboxes.
73...Carl KM1H
>
>> Even 811A's at 1500V may be a safety issue. I prefer to err on the
>safe
>> side.
>
>OK ;-)
>
>73, Tom W8JI
>
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