[AMPS] VHF visitation (was power handling...)

measures 2@vc.net
Wed, 8 Mar 2000 00:41:40 -0700


>
>>>When it had a VHF visitation, my old ''plywood box'' amplifier would
>>>Blow the parasitic suppressor resistors into something like cosmic
>>>dust.   My guess is that the engine for this transaction was the
>>>1000 Joules that were stored in the 9200v supply.  The transaction
>>>took place so quickly that it never tripped the breakers.
>
>>>>But they resistors don't blow up nor do they "look">>
>>physically damaged.
>>>>
>>>The above resistors were disappeared.  Forrest Gump was right.
>
>Dear me, I did see the Forrest Gump movie, but I recall not the simile, 
>could you please enlighten this luddite?
>
€  "Shit happens" -- Forrest Gump.  Murphy said something similar.  

>Then - the plywood box amp seems to have an extraordianry ability.  Does 
>this amplifier still exist?  

Yes

>As a prospective author, I'd dearly love to 
>make some network measurements on it, and outfit it with peak measurement 
>apparatus to see what is "up" with it.  

To do this, you would have to remove the present all Ni-Cr alloy vhf 
suppressor device and install a copy of the suppressor whose R-supp 
virtually disappeared.  . 

> VHFYou say it has a "VHF visitation" so 
>I assume you actually measured a VHF occurance.  What was the frequency 
>observed?  

A bit under 68MHz.  No measurement was made during the big-bang.  The 
anode-resonance that apparently supported the event was found with a 
dipmeter.. 

> What was the length of time the pulse lasted (if it was a pulse)? 

beats me.  It sounded like a shotgun, only louder.  .  

>  How did you discern that it was not one of Eimac's fabled "barnacle" 
>incidents?
>
At 15kV, the tube subsequently exhibited an above avg.  vacuum.  This was 
hardly surprising since the tube had recently been rebuilt by Econco 
Broadcast Services.  A VHF visitation seemed likely because the 
carbon-comp R which disappeared  was DC shorted by <2milli-ohms of 
buswire.  //  RE:  Eimac.   I have never seen an Eimac engineering 
bulletin on parasites.  Have you? //  I have listened to Rauch's banter 
about appearing/disappearing barnacles.  It reminded me of a ''sea 
story'' that is oft' heard over brewskis.  .  

>If this amplifier does not still exist, 

It still exists.  150 in does 15 out.   When I used to tune it up (with a 
pulser), my neighbors' porch lights blinked.  

>can you provide adequate details so 
>that it can be completely replicated?  Oh, such a learning experience that 
>should provide!

Replication is quite straightforeward, and can be accomplished with 
ordinary hand tools -  thanks to precision sheet metal shears, PEM-nut 
fasteners plus screwed & glued douglas fir plywood.  . .  See "Ugly"  on 
my Web site.  Photos are provided of a slightly smaller version using a 
more linear tube. .  A simplified diagram of the only thing in the 
amplifier that is somewhat unique is provided.  (the grid circuitry) 
>
cheers, Fred

-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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