The AM Forum

This was given to me today. It does not appear or smell like it leaks. 1uF 15KV. Honestly I am not sure what to use it for. I can clean it up and give it a little paint. The rust is surface only. Can's fine!

you could use it for a modified Heising reactor coupling cap.  8 kOhm Z at 20 Hz, 4 kOhm at 40 Hz, etc. ... beefus

Looks awful small for 1 uF @ 15KV but it would be perfect for a hi-pot tester. I wound up with three 2 uF @ 5KV in series for my tester.

Carl
KM1H

Just mask out where the specs are printed and spray away.
Good cap for a lightning generator. 

Looks about the same physical size as the heising cap in my BTA-1M, which is rated 2uf at 6kv - about the same size in Joules...

Also could apply naval jelly to affected areas, clean off, and overspray with clear coat. Maintains old appearance without allowing additional rusting.

It would also work for a high voltage, low current power supply, something like 12 kv at 83 mills, for 1 kw DC input.

Good ideas! The naval jelly seems like a good fix for the rust, as I prefer the old look.
the case less insulators is 9x8x4 inches.

If I did the Heising, I could put it between the cold end of the mod iron and GND. I also have a 6uF 12KV one that is much newer but not much bigger - That one I should save for a power supply! My reactor is 60H. There was a warning about resonances and the need for high voltage ratings IIRC.

The PA can run at 3KV/300mA to 500mA for carrier condition, so it would present a load of 10K to 6K.
When the Xc equals the modulator load impedance, is that the -3dB point?

yes, actually a bit more complicated since some of the components have resistive properties and some have reactive, as the frequency changes but it will be close ... 73 ...John

  We just had our Environmental Dept. disposed of six of this style of oil fill
capactors that was removed from a radio room aboard a scrap ship.. One of the oil
fill capactors had a small leak and after testing we found that the oil was found
to be contaminant with ( PCb's ) with a ppm greater than 200 ppm....

Let the PCB argument commence...

I'm not going to argue about PCB's... but would like to point out that (as seems to be implied in the posts above), Pyranol is indeed a PCB.
It won't leap out of the can and bite you though  ;D

That does look kind of small for 1 uf at 15 kv. Although it's big for .1 uf. What does your C-meter say? Or just charge it to some voltage, discharge through 1 Meg and time it!

-Charles

Can I have the ones that were not leaking?

Truthfully and on close scrutiny it says 1uF. It also says for DC filter use only, whatever that implies, maybe a rigid adherence to the voltage rating or an avoidance of high currents. Not yet tested. I should do so.

hi Patrick ... ESR could be an issue ... do you have a way to test this parameter, if not a quick and dirty test could be done ...let me know ...73  John

The only way I can think of to do it is to use some high frequency of AC to measure the total impedance and subtract the known (name plate) reactance. What is the quick and dirty way to do a good ESR test?

ok here goes ...at 60 Hz the impedance of your ideal capacitor would be: Xc = 1 / 2 (3.1416)(60)(1E-6) or 2654 Ohms purely reactive.  All real world caps have some equivalent series resistance or ESR so our problem could model as:

                   A                                  B
ac source   ------  known resistance ----- |
                                                        |
                                                       ESR
                                                        |
                                                        |
                                                    ideal cap
                                                        |
                                                        |
Use an accurate 2 ch oscope at points A and B to ground. As you vary the source freq, when twice the voltage drop at B equals the applied voltage at A then the voltages have divided equally. since the capacitor is reactive then should also a phase shift of approx 45 degrees between the traces.  the ESR of the capacitor will shift the freq from calculated ... this method is not very accurate but will give a ballpark fig .....73 ...John

I see. Ok, I can try it later; I should go ahead and do all my significant oil caps while the setup is in place.

It occurs to me I have many I may not use. I was at a radio club "club donation sale" today and picked up a Motorola SHF power supply chassis of some sort with an interesting 3-section oil cap on it, never used. Here are my major "oilers". I just thought it would be nice to show them.

forgot this monster.. It says 4uF 5KV, but is the same size as the 8uF 5KV ones and it has a ground lug, so maybe it is a dual.

Then you have a big hand, it looked smaller to me.

Carl

YA'll are making feel bad with the nice oil caps.
I gave a 20UF@10KV away as part of a deal selling a beautiful HB transmitter. It will probably never be heard on the air ever!!!!!
One of my many regretful 'shudda kept it' things.
Fred

The HB or the cap? I am sure someone must be using the HB TX! Hopefully the cap is still around.. waiting to be used!

Like the pair of BC-610E's that I sold for $25 apiece back in 1970 (I kept the HV plate transformers, spare tubes and coils, and gave the guy a couple of pole pigs), because I had no place to store them. Never heard the guy on the air again nor ever saw a trace of him afterwards.

So what did your buyer do with the transmitter, if he didn't put it on the air? Some bottom feeder who parted out the transmitter on ePay?  Very few trophy collectors are interested in homebrew transmitters, no matter how well built.

I still have the pair of 400 mfd @ 2500 volt oil caps that were given to me this past summer.

Yes, Pyranol is a General Electric trade name for PCB.  G-E Paranoid capacitors.

I hate to see HB rigs parted, especially if they are impressive or finely made things that might have taken someone a couple years to build. parting BC-610's is about as wrong as it gets, unless they are really unrepairable.

400uF/2500V? 1250J. I'm waiting for the flashover from that filter.. You need a big laser, Don. Have you ever used those?