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[AMPS] PT-1000-K1Mh

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Subject: [AMPS] PT-1000-K1Mh
From: (Rich Measures)
Date: Wed, 25 Mar 98 19:36:54 -0800
>               Rich, I would agree that parasitics are no one's fault if this 
> is the
>problem.  My basic problem here is that I heard this amp on the air a week
>before I bought it--unless the guy is a total fraud which I do not believe.

When an amplifier is  operated in a different location, with different 
equipment, using a different load, things change.  

> Going from this state to what happened after I dropped it leads me to
>believe this bounce had something to do with it.  The capacitors are very
>clean which leads me and my friend to believe that arcing has not been a
>problem before.  

Can you see the arc?

>Thus, something went seriously wrong that caused high
>voltage to arc to ground to do the damage it did to metering circuits, etc.
>I don't want to discount your products or ideas but I feel this amp must
>have worked correctly to some degree or he would not have kept it sso long
>or in as good a condition.  

The VHF parasitic suppressor design we use operates on the same principle 
as the suppressor that is currently in the PT1000 amplifier.  The 
differences are that our suppressors are made with vhf-lossy Ni-Cr-Fe 
wire instead of Cu wire, and we use a suppressor resistor (Rs) that can 
safely dissipate more power, which allows the use of more Ls in order to 
improve suppressor performance (less VHF-Rp).  A graph is available that 
shows the difference measured by Wes, N7WS using a Hewlett-Packard Model 
4191A RF Impedance Analyzer..  If you are interested, you can see it at:

>Thus, unless presented with overwhelming
>evidence to the contrary, 

So pull the mains plug, couple a dipmeter to the HV DC blocking C and see 
what's what in the evidence department.    

>I must take the responsibility for what happened.
> I just pray it can be fixed and put back into proper working condition.
Other users of Viewstar amplifiers reported arcing problems. It turned 
out not to be their fault.  

>I want to try to answer some of the various questions that have been put to
>me by everyone so I can do it all in one email.  <G>  To date, we have
>driven it to no more than 200 watts out for testing purposes.  This is
>achieved with about 20 watts input which seems right to me.  

For the existing tank design, the RL of the tube will not be right (c. 4k 
ohms) unless you apply c. 50w of drive.  

>It is past
>this point when arcing occurs on just the plate tuning cap as far as we can
>tell.  The arcing occurrd on 20 meters here on my beam at an swr of 1.3 to
>1 at the tuning frequency.  I haven't heard from my friend in a couple of
>days so I don't know if he has tested it elsewhere into his dummy load.

What the amplifier did at his house has no bearing on what the amplifier 
is doing at your house.  There are too many Variables.  
>Thanks Rich and all for your thoughts.  73

You are welcome, Kevin


R. L. Measures, 805-386-3734, AG6K   

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