>
>
>
>> Corona in a amplifier with a 3000V anode supply?
>>
>> >I thankyou Alek for that information. I don't think I'll pursue it
>> >anymore. The amp I have is 15 plus years old with the original
>> >3-500Z tubes and it still puts out 800 watts PLUS, with no sign of
>> >arcing, at least not yet. I have never heard of corona washers
>> >before belive it or not. I still learn something everyday, and that
>> >is good.
>
>Anyone who has built a Heath SB-1000 is very familiar with the corona
>washer.
>It is included with the kit. Perhaps one can download the manual
>from BAMA or somewhere if you want to see pictorials and installation
>instructions for it. It is a simple flat washer that is placed on one of the
>band
> switch contacts.
>
>There is seldom any one cause for the need for special additions to an
>amp design. W8JI explains well on his web site the proper way to construct
>a band switched tank assembly. Heath had no control over the level of
>soldering expertise that Joe Six-Pack would have, so they hedged their
>bet with the washer.
It's always the customer's fault.
>In addition, the nearness of that particular switch
>terminal
>to the chassis and other components (layout) is something unique to the
>SB-1000. Because this amp operates on at least 8 bands including 160 meters
>in a very small RF compartment using all air wound inductors, all bets are
>off
>concerning how much corona and point-to-point arcing can occur. Depending
>on the load and tuning (or mis-tuning) it is certainly enough to toast the
>band
>switch on the SB-1000. It was certainly enough to toast a Radio Switch Corp.
>model 86 switch on my 8877 amp with a similar layout to the SB-1000.
>This tells me that a >7000 volt arc can be produced from a 4000 volt anode
>supply. The model 86 switch does not have multiple fingers that
>short out unused taps on the tank coil. This style switch prohibits
>successful
>use on more than the traditional 5 bands (80-40-20-15-10m) without resulting
>fireworks. (been there, done that, $136 mistake!) If you will look at the
>band
>switches on the AL-1500, Alpha 77 series, and other 6-9 band amps, you will
>see how each manufacturer avoided making a nice Tesla coil out of a tank
>circuit.
>
good point
>Sorry for the rambling, but I wanted to cover a couple of topics.
>
>(((73)))
>Phil, K5PC
>
>
>
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>
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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