At 09:17 AM 3/30/98 -0700, you wrote:
>Jay (W7CW) found these capacitors. They are Murata (now Murata-Erie)
>ceramic caps,
>rated for 20 KV DC working voltage. They are 4800 pf (0.0048 uF). Those had
>a Z5V ceramic dielectric, with a peak in capacitance at about 15 degrees C.
>The capacitance drops as temperature increases.
>The dielectric loss is high, dissipation factor of 1.5%. It drops with
>temp., but rises with frequency.
>These capacitors were rated for DC, and have curves as high as a few MHz.
>where the loss rises and DF is higher than a percent. I would be extremely
>wary of operating them anywhere close to maximum voltage with RF. However,
>if you seriously derate them, you could probably block 500 volts or so,
>with Rf applied. You will find that they will heat, and not be stable in
>value as they heat.
Hi John, Thanks for the info. Do you think these will be ok for bypass
capacitors at the base of my plate choke then? They would be subject to
6000 volts, and would be grounding any stray 1.8 through 30Mhz rf leaking
past the choke.
73 Jay W7CW
1AB Ranch
Gillette, Wyoming
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