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RFC with 5 or 6 "pies".

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Ian Field
Guest

Sat Oct 04, 2014 10:35 pm   



When I was much younger and harvested components from valve (tube) TVs &
radios, pie-wound chokes were pretty common - and I added a decent number to
my junk box.

Unfortunately, the exposed pie windings were vulnerable and none survived
being in the junk box.

Just wondering whether anywhere still makes them?

The usual types were either wound on a hollow paxolin tube, or a high value
resistor - one of those old carbon composition types cemented into a ceramic
tube.

Michael Black
Guest

Tue Oct 07, 2014 7:30 am   



On Sat, 4 Oct 2014, Ian Field wrote:

Quote:
When I was much younger and harvested components from valve (tube) TVs &
radios, pie-wound chokes were pretty common - and I added a decent number to
my junk box.

Unfortunately, the exposed pie windings were vulnerable and none survived
being in the junk box.

Just wondering whether anywhere still makes them?

The usual types were either wound on a hollow paxolin tube, or a high value
resistor - one of those old carbon composition types cemented into a ceramic
tube.

I read somewhere recently that they were still available, but I cant'
remember where I read it, or where they were being sold.

The construction articles will specify "2.5mH", really quite large values,
though every so often they'd specify only "1mH". That later seemed to be
overkill, I wondered if it was one of those things where a value became
familiar, and readily available, so it was self-perpetuating.

Generally, I don't think the moulded RFCs of more recent times (they look
moninally like resistors, except a lighter color, but they do have color
coding) are appreciably less components than the old pie wound ones,
except maybe they don't get as large in value.

The problem now is that even the old scrap is hard to get, newer equipment
with newer parts is what gets discarded. Good in lots of ways, but lousy
if you need those old RF chokes or tube sockets.

Michael

Ian Field
Guest

Wed Oct 08, 2014 1:57 am   



"Michael Black" <et472_at_ncf.ca> wrote in message
news:alpine.LNX.2.02.1410062159270.14047_at_darkstar.example.org...
Quote:
On Sat, 4 Oct 2014, Ian Field wrote:

When I was much younger and harvested components from valve (tube) TVs &
radios, pie-wound chokes were pretty common - and I added a decent number
to my junk box.

Unfortunately, the exposed pie windings were vulnerable and none survived
being in the junk box.

Just wondering whether anywhere still makes them?

The usual types were either wound on a hollow paxolin tube, or a high
value resistor - one of those old carbon composition types cemented into
a ceramic tube.
I read somewhere recently that they were still available, but I cant'
remember where I read it, or where they were being sold.

The construction articles will specify "2.5mH", really quite large values,
though every so often they'd specify only "1mH". That later seemed to be
overkill, I wondered if it was one of those things where a value became
familiar, and readily available, so it was self-perpetuating.

Generally, I don't think the moulded RFCs of more recent times (they look
moninally like resistors, except a lighter color, but they do have color
coding) are appreciably less components than the old pie wound ones,
except maybe they don't get as large in value.

The problem now is that even the old scrap is hard to get, newer equipment
with newer parts is what gets discarded. Good in lots of ways, but lousy
if you need those old RF chokes or tube sockets.


Somewhere I have what could be a Philips EE kit 10mH RFC, the ones in all
the kits I had were bare single pie chokes, most were dry but one was wax
impregnated.

The one I came by more recently would be a later model as its resin dipped.

IIRC - the ballast in a CFL is usually a few mH, but probably not a lot of
good for RF.

David Platt
Guest

Wed Oct 08, 2014 2:30 am   



Quote:
The construction articles will specify "2.5mH", really quite large values,
though every so often they'd specify only "1mH". That later seemed to be
overkill, I wondered if it was one of those things where a value became
familiar, and readily available, so it was self-perpetuating.

Generally, I don't think the moulded RFCs of more recent times (they look
moninally like resistors, except a lighter color, but they do have color
coding) are appreciably less components than the old pie wound ones,
except maybe they don't get as large in value.


For what it's worth... Hammond still makes some 3-pi-wound RF
inductors. Mouser stocks a few... from 1 mH up to 25 mH.

Ian Field
Guest

Wed Oct 08, 2014 2:33 am   



"David Platt" <dplatt_at_coop.radagast.org> wrote in message
news:d4vdgb-0op.ln1_at_coop.radagast.org...
Quote:
The construction articles will specify "2.5mH", really quite large
values,
though every so often they'd specify only "1mH". That later seemed to be
overkill, I wondered if it was one of those things where a value became
familiar, and readily available, so it was self-perpetuating.

Generally, I don't think the moulded RFCs of more recent times (they look
moninally like resistors, except a lighter color, but they do have color
coding) are appreciably less components than the old pie wound ones,
except maybe they don't get as large in value.

For what it's worth... Hammond still makes some 3-pi-wound RF
inductors. Mouser stocks a few... from 1 mH up to 25 mH.


Thanks - its mostly out of curiosity, but handy to know should I happen to
need some.

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