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Hi Tracey - I used one of these in my 3CX3000 amp

Mine's a 2000pF rated at 20kV.? I have seen them on Ebay for about a tenner - a lot cheaper than the ceramic one you were looking at which I think was ?50.? I'd bought the big ceramic caps in the past off Mr Jandek at Friedrichshafen (a big stand in the fleamarket with Russian vacuum capacitors etc, usually on the back wall - remember him?)? for about 10 euros.? He wasn't there last year (and who knows what will happen this year?)? but he might still be in business.? He was based in Bielefeld last I heard.

I can only state (rather unscientifically) that I haven't blown it up yet.? ?I also use one of the plastic LCC caps as a matching series capacitor on my ground-level fed 3/8 wave wibbly-wonky-sort-of-inverted-L on 160m.? ?The only time I damaged that was when I inadvertently reversed the Land Rover over the feedpoint.? I can't blame RF current for that, only clumsy driving.

Something similar

Alternatively how about getting in touch with Alex UR4LL?? He's a thoroughly reliable chap and will almost certainly have a Russian made equivalent of the ceramic capacitors you mentioned - at a pretty good price from what I remember.

Hope that helps

73

Dave G0OIL

On Saturday, 21 March 2020, 23:04:52 GMT, Tracey Gardner via Groups.Io <tracey.gardner=[email protected]> wrote:

?

Having looked at the Draloric data sheet for the 2500pf, R85, PE 200, 14kvp Ceramic Disc Capacitor, it looks like it is rated at 60 amps RMS

?

Tracey G5VU

?

----- Original Message -----

From: Tracey Gardner via Groups.Io <tracey.gardner@...>

Reply-To: <[email protected]>

To: <[email protected]>

Sent: 21/03/2020 15:22:49

Subject: [ham-amplifiers] Plate blocking caps YC156

---

A number of high voltage/current rating ceramic capacitors??have just come up on eBay in the UK.

It looks like they have come out of some kind of RF heating or medical equipment.

I'd be grateful for any thoughts as to their suitability for use as the plate blocking capacitors for a YC156 amp.

The description and eBay item numbers are as follows

Draloric, 2500pf, PE 200, 14kvp Ceramic Disc Capacitor: Item Number 114153436756

Unilator Type 860, 15kv 2000pf, Capacitor: eBay item number:114154806911

Unilator Type 807, 14kv 2000pf Ceramic Disc Capacitor: eBay item number:114154801609

Unilator Type 910, 15kv 1000pf Ceramic Disc Capacitor: eBay item number:114154801080

Many thanks

?

Tracey G5VU

?

----- Original Message -----
From: Jim VE7RF <jim.thom@...>
Reply-To: <[email protected]>
To: <[email protected]>
Sent: 29/12/2019 15:12:42
Subject: Re: [ham-amplifiers] Plate blocking caps YC156


The??problem??with??broadcast?? mica's (or??any??mica)??is??they??won't handle?? any current??on??higher??freqs.??But??they are??NPO.?? Drake used switchable mica's??in their??MN-2000??ant??tuner (along??with??2 x air??variables).?? Drake??used??7 (SEVEN)?? mica's??in??parallel....just??for 10m??band.....just to handle 1200w??pep into??some??swr.??

Drake??used??a single??700 pf??(NPO) mica??to??pad??the 1600??pf??load??cap on??80m band....??on their L4B??80-10??amp.

Those CDE and??similar??mica??caps??are??typ rated??at?? 1??mhz??for??max current.??> 6??mhz, they??have??fallen??off really??fast.??>20??mhz,??they??are??down??to??nothing.

Mica's??work??superb??on??low??bands (<6 mhz)....??and ceramic??caps work??superb??>2-3 mhz.

For??a plate??block??cap, ceramic??is??used,??since??we??require??a cap(s) that??will??handle loads??of??current on??21-29.7??mhz. (+6M).????On lower??bands,??plate??block??cap??current??drops??way??off.....non??issue.

HEC??is??still made??in PA...amish??country.??

Download??the??main??catalog for??CERAMIC????

Draloric is??still??made in??germany.

Centralab??was??bought??out??by??ITT-Jennings.??Centralab??(ITT-Jennings)????857 /??859??is??the??same??as a HEC?? HT-57??/??HT-59

Everything??else??is??a chinese copy.?? Also??factor??in??the??heat??from??the??anode??will??travel??down??the strap..to??one??side??of??plate block??caps.

Jim?? VE7RF