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Odd value capacitors?

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Davek0974
(@davek0974)
Posts: 77
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I'm trying to recap a Philips 219B set and have come across some oddities that need replacing...

0.0027uf
0.000725uf
0.001615uf
0.016uf
0.025uf

any ideas on a good replacement, these are mostly listed as bandpass coupling or oscillator tracking items

thanks

 
Posted : 13/10/2015 9:49 pm
EDDINNING
(@eddinning)
Posts: 208
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Hi Dave, if you have a good spares box you may well be able to make then up from smaller values in parallel. In this application (tuned circuit) polystyrene or mica caps would be the type to use.

The .016 and .025 are a bit large and sound more like harmonic tuning caps for the LOPT. These definitely need to be HV caps and used to be supplied by the service companies as specific parts.

Ed

 
Posted : 13/10/2015 10:28 pm
Davek0974
(@davek0974)
Posts: 77
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Topic starter
 

Thanks,

this is a radio, battery operated valve.

I will look into the parallel idea.

What is the deciding factor between choice of cap - polypropylene, polystyrene, ceramic, mica etc????

 
Posted : 13/10/2015 10:43 pm
sideband
(@sideband)
Posts: 4214
Famed Member Moderator
 

I'm trying to recap a Philips 219B set and have come across some oddities that need replacing...

0.0027uf
0.000725uf
0.001615uf
0.016uf
0.025uf

any ideas on a good replacement, these are mostly listed as bandpass coupling or oscillator tracking items

thanks

Out of those, the only critical ones are probably .000725uF (725pF) and .001615uF (1,615pF) which are likely associated with oscillator/RF tuning. Probably better to make those up from series or parallel combinations. The others (.0027uF, .016uF and .025uF) could be replaced by 0.0022 or 0.0033uF, 0.015uF and 0.022uF respectively.

What is the deciding factor between choice of cap - polypropylene, polystyrene, ceramic, mica etc????

Polyprop, polystyrene types are best for audio coupling and ht decoupling. Ceramic for IF/RF decoupling and Mica for tuning/padding etc. Ceramic caps tend to have a fairly wide tolerance spread so not so good for tuning/padding etc. Mica are stable and (usually) close tolerance so good for RF

 
Posted : 14/10/2015 1:22 pm
Cathovisor
(@cathovisor)
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I'm trying to recap a Philips 219B set and have come across some oddities that need replacing...

Do you *know* they need replacing?

 
Posted : 14/10/2015 1:32 pm
Davek0974
(@davek0974)
Posts: 77
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I'm trying to recap a Philips 219B set and have come across some oddities that need replacing...

Do you *know* they need replacing?

One of the waxed mica one has snapped off where the lead joins the body, two of the others seem to have cracked or split.

 
Posted : 14/10/2015 3:23 pm
Dr Wobble
(@dr-wobble)
Posts: 702
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The 1615p/odd value caps rings a bell, I think I may have some, somewhere. I remember asking about these over on UKVRR a while back. Will check.

Send me a PM in a few days if I forget, Andy.

Curiously curious

 
Posted : 05/12/2015 4:30 pm
Terrykc
(@terrykc)
Posts: 4005
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One of the waxed mica one has snapped off where the lead joins the body ...

That shouldn't be a problem as the eyelets which hold the assembly together (and will still be clearly visible on a waxed capacitor) are also the connections.

Heat the eyelet and wipe off the molten wax. Repeat as necessary to ensure that all trace of the wax is removed from the eyelet/

Now solder on a new lead out wire.

Gently heat the entire capacitor until all the wax has melted and let it flow evenly over the surface (or you could add a few drops of candle wax).

You can now replace the capacitor in the set it came from.

When all else fails, read the instructions

 
Posted : 05/12/2015 11:31 pm
Dr Wobble
(@dr-wobble)
Posts: 702
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Had a look for the caps, but can't find them. Will keep looking,

Andy.

Curiously curious

 
Posted : 09/12/2015 1:30 pm
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