High Voltage- High Current Caps for ATUs

[vk2aah]

Hi,

I have a Ten Tec 229 ATU that I am refurbishing and am looking for a local source of ceramic capacitors used in these ATUs. I can source them from Ten Tec for a ridiculous amount (about $10 per ceramic) but wondered if anyone knew of an importer for these. The capacitors used are 470pf 2kV ceramics, approximately 20mm diameter. The diameter according to Ten Tec is critical in this application. The high voltage caps I've found are less than 10mm.

Any ideas? I've rung the usual suspects (Farnell, WES, Arrow etc).

Cheers,


Richard
VK2AAH

[VK7ZL]

Why do you need to change them? If they look OK (not burnt or cracked) and they measure 470pF, or close enough, they will be fine.

[vk2aah]

Yes I checked them and they were within reasonable tolerance, however given that the switch was fried (read: tracks vapourised) as a result of someone else's abuse Ten-Tec's service manager thought it wise to replace the ceramics at the same time. I've now replaced the burnt out switch and have found a superb alternative to these ceramics... go in to EBay and search for "Doorknob Capacitors". These are mostly found in the old USSR (I'm buying mine from the Ukraine) and were made for high power broadcast output stages. I just paid $23US including postage for four, these are rated at 16kV- much higher than the old 2kV ceramics.

Thanks to the other ham who emailed me privately! These new caps should outlast me without any problems.

Cheers,

Richard
VK2AAH

[vk2aah]

Just a postscript for VK7ZL...

ATU works fine at legal power on all bands 40 and up. Last night I was using it on 80m and found that I needed to switch in 3 of the caps (still the original ceramics at this time) to tune the antenna and while it worked perfectly at 50W increasing this to about 300W caused the SWR to rise dramatically after about 5-10 seconds. After a short time in rx the SWR returned to normal. All other bands I only need a very small amount of C and it happily runs 400W (so it should given it is rated at 2kW).

Cheers

Richard