[AMPS] TV Doorknobs as Plate Blockers

[Larry Molitor]

At 11:12 PM 6/23/99 -0400, you wrote:
>
>K5PC wrote:
>
>"Make sure you have an RF choke accross the output of the amp because is is
>just a matter of time until those "TV" type doorknobs are going to smoke.
>They are not RF rated for 1500 watts."
>
>Not to argue with K5PC, but I've had such caps as plate blockers in my 15M
>3-1000Z for ten years with no problems whatsoever.
>
>What is it about these caps that makes them unsuitable?  Ceramic design,
>15KV rating, and with appropriate amounts of C - what is it?
>
>73,
>
>Dave/K8CC

Dave, they have a bad rep, perhaps justifibly, because the RF current
capacity is very low. They were only ment to be filter caps on the CRT
anode supply. No consideration was given to RF specs when the ceramic
material was chosen. I don't know which material is actually used in them,
but it's pretty poor for RF. I have melted down a few when used in tanks.
As long as you pay attention to the RF current, they work great and last a
long time. Just my opinion, take it for what it's worth.

73,

Larry - W7IUV
w7iuv@arrl.net
http://www.axtek.com/w7iuv


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