[Amps] Serious design stage

[Jim Isbell]

Two reasons for the 4-1000A:

a) I already have it with socket etc.

b) Its the coolest looking tube in the world and part of this project, 
maybe 85%, is to create a linear that will cause ooohs and aaaahhs from 
the onlookers as they view the 4-1000A and the 866's  lit up behind the 
window in the front of the cabinet.

I have never seen an 8171...are they similar??

Two reasons for using the 12KVA transformer:

a) Its here and weighs "a ton".

b) I dont want to move it far enough to sell it and its closer to the 
transmitter shack then it is to the street.

rlm wrote:

>
> On Apr 20, 2004, at 11:29 AM, Jim Isbell wrote:
>
>> After collecting parts for most of a year I am in the serious design 
>> stage of a 4-1000A linear.  The power supply, because of its size is 
>> to be external and connected by a cable.
>>
>> In the first design I was going to bring the 6500VDC power through a 
>> cable to the linear.  But then it occurred to me that since the main 
>> reason for the separate supply was the size...which is MOSTLY the 
>> 12KVA transformer I am using.  It might be safer to just make the 
>> transformer external and have the rectifiers and filter capacitors in 
>> the transmitter case thus allowing the only the transmission of AC, 
>> at a lower potential, (using a voltage doubler circuit) in the 
>> cable.  Thus, by just turning off the input power I could eliminate 
>> the potential on the cable instantly...or almost so...while the 
>> filter capacitors which are the biggest danger would be in the 
>> transmitter cage and would be connected to shorting circuits 
>> controlled by the safety switches on the lid of the transmitter.
>>
>> There must be some reason this is not a good idea as I have never 
>> seen it done.
>>
>> Any comments???
>
>
> ?  Jim -- I see it as a sound idea provided there is room for the 
> filter capacitors in the RF unit.  However, a 12kva transformer would 
> be more suitable for an 8171 than an 8166/4-1000A.  Switching to such 
> would not require a larger chassis since either tube requires c. 8" x 
> 8" of chassis space.  Advantages with the 8171 are a simpler tuned 
> input circuit, a quieter blower, and 6x the peak emission.   If you 
> have a 4" deep chassis, Peter Dahl makes a 7.5v, 75A filament 
> transformer that will fit in a 4" chassis.   On E-bay, I've seen 8171s 
> go for c. $300.
>
> cheerz
>
>>
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>>
> Rich Measures, AG6K, 805.386.3734.  www.somis.org/
>
>