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/
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