It is currently Mon Oct 23, 2017 1:32 am

Odd value capacitors?

Hints and tips for vintage technology repair and restoration
 
Posts: 49
Joined: Mon Jan 19, 2015 9:42 pm

Odd value capacitors?

Post by Davek0974 » Tue Oct 13, 2015 8:49 pm

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

 
Posts: 217
Joined: Mon Jun 04, 2012 11:40 am
Location: Newcastle on Tyne

Re: Odd value capacitors?

Post by Ed Dinning » Tue Oct 13, 2015 9:28 pm

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

 
Posts: 49
Joined: Mon Jan 19, 2015 9:42 pm

Re: Odd value capacitors?

Post by Davek0974 » Tue Oct 13, 2015 9:43 pm

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????

 
Posts: 2920
Joined: Wed Jul 27, 2011 7:13 pm
Location: Croydon

Re: Odd value capacitors?

Post by sideband » Wed Oct 14, 2015 12:22 pm

Davek0974 wrote: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.

Davek0974 wrote:
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

 
Posts: 2714
Joined: Sun Sep 01, 2013 6:19 pm
Location: Behind the sofa

Re: Odd value capacitors?

Post by Cathovisor » Wed Oct 14, 2015 12:32 pm

Davek0974 wrote:I'm trying to recap a Philips 219B set and have come across some oddities that need replacing...

Do you *know* they need replacing?

 
Posts: 49
Joined: Mon Jan 19, 2015 9:42 pm

Re: Odd value capacitors?

Post by Davek0974 » Wed Oct 14, 2015 2:23 pm

Cathovisor wrote:
Davek0974 wrote: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.

 
Posts: 761
Joined: Sat Jan 07, 2012 10:21 am
Location: Sleaford lincs

Re: Odd value capacitors?

Post by Dr Wobble » Sat Dec 05, 2015 4:30 pm

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.

 
Posts: 3781
Joined: Sun Feb 12, 2012 7:43 pm
Location: North Hykeham, Lincolnshire and Ilford, Essex (but not for much longer ...!)

Re: Odd value capacitors?

Post by Terrykc » Sat Dec 05, 2015 11:31 pm

Davek0974 wrote: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.

 
Posts: 761
Joined: Sat Jan 07, 2012 10:21 am
Location: Sleaford lincs

Re: Odd value capacitors?

Post by Dr Wobble » Wed Dec 09, 2015 1:30 pm

Had a look for the caps, but can't find them. Will keep looking,

Andy.


Return to Tips, Solutions & Recommendations



Who is online

Users browsing this forum: No registered users and 1 guest