The AM Forum

Got a call from a friend this afternoon who is talking with a capacitor manufacturer about producing some caps for the radio, guitar amp, and audio crowd. We've talked about this in the past but never got to it. Now it looks like it will happen.

The question is, what values would be the most handy to have supplied into the future for restoring old gear? Obviously we can't do a lot of oddball values as we're mainly looking for values that will sell well and be attractive from a production prospective. The few that popped to mind for me were:

 .1, .01, and .47 mfd at both 400 and 600 vdc. I also specified axial lead instead of the radial leads found on Orange drops since axial leads are better suited to our needs. I'm looking for other values that are likely to be encountered often enough to warrant production. Maybe 6-12 different values to choose from.

The meeting is set for tomorrow, so timely input is critical.

TNX!

Todd,
Add in
.001, .02 .05, .2

Todd,

That would be a great help to all who keep the old stuff running. I definitely agree with Carl that .001 and .05 @ the two HV values would be important to have around.

Rob

Thanks guys. I'll combine these with others from folks on some of the lists and come up with a master list to send off tonight. No guarantees it will come to pass, but you gotta start somewhere. As the old saying goes, nothing ventured, nothing gained.

I hope you are not talking audio fool prices because there are plenty of caps out there to be had for cheap money. The rare values are over 1uf and over 600 volts.

y'all pretty much picked up the values. I prefer 600V caps to cover most all regular applications, but some of those might be physically larger than desired in the usual 150-250v circuits. I like to keep full stock of sets, in 400V and 600V ratings. A lot of times I end up with odd values because of buying surplus. Like recently 0.007@630V for 17 cents each. They work for me when applicable. I'm grateful for whatever is available. It's hard to keep up with all the odd "normal" value decades.
0.01
0.02 or 0.022 or 0.027
0.033 or 0.039
0.047
0.05
0.068
0.082
- and then run into odd types like 0.015 and everything else. Well whatever is useful and not redundant, I'll be grateful for a good supply of reasonably priced capacitors.

BTW when did caps change from values like classic resistors to 'even' decimal values, or did they ever? It seems like today, just about any value is liable to show up.

Some 500 and 1000pf@6KV for plate bypasses wud be nice!

Most caps can be had on the market at present in most values and voltages.

The way to go about this is to first make a list of candidates, then look at the two big retail distributor's
catalogs: Mouser & DigiKey and see if the values you want are available.

If not, then do an online search for current stock, then NOS (surplus).

IF the values you want are available from any of these sources then there is no way that a
"custom run" will cost less than the catalog price, and if it is less, not by enough to make it
financially reasonable to do the run. Perhaps if you have a dozen or more resellers already lined
up to take 1,000pc quantities in advance, maybe.

The area where there is something of a shortage, although LESS than a few years ago is in the
electrolytic replacement department - in particular "twist loc" style. However, there are now a
range of new manufactured replacement twist loc cans for the guitar and radio replacement
application all over the place.

It would be unlikely that a US mfr can beat the wholesale price on these import cans...

The only type of cap that I am aware of that can not be purchased new, off-the-shelf now is
the large "computer" electrolytic can, high capacitance and ~100vdc and down rated... these
are of interest to the audio people, not usually to ham or radio, guitar people.

Caps are a tough biz... you gotta sell big quantity to make it worthwhile even trying to do
a run.

My 2cents...


                  _-_-bear

Those 6kV and even 10kV discaps are cheap at Mouser.

For bypassing in a receiver the values are far from critical, a .1 can be replaced with anything down to a .05 or even lower. Exceptions would be for the very low IF's and tuning ranges.

The design was engineered using the best calculated values, what was produced may have been a lot different when the bean counters got thru.  Take the Nationals that were designed when engineers ran the show. The bypasses were .1's. After WW2 the company had all new management and the bypasses were mostly .05 and even down to .01 in a short time. The same thing happened in even the high end consumer radios.

I see on some forums when posters get anal over having to use all the original values; obviously they never opened a electronics book. These are the same ones who actually have a religious belief that the Orange Drop slugs actually offer any extra benefit.

I also buy odd value surplus lots at sometimes well under .10 each in 100 or so quantities.

Carl
KM1H

Carl,
Orange Drops suck at RF due to high ESL. I wonder if you ever saw the Sanders custom foil caps. They blew orange drops out of the water with their foil termination method.

Lotta old-timey cap values here;

http://www.justradios.com/orderform.html (http://www.justradios.com/orderform.html)

Yep, above low HF the OD's are about as good as the old papers when new.  There is some comment about the old HRO-60's with paper caps and the later runs using discs in the current ER. The writer cant figure out why the later one is more sensitive after both were fully overhauled ::)

The 60 I use came from a guy who bought it from an estate. The SK used all OD's and miswired about half of them and missed a pair. After cleaning up the mess and replacing 20+ resistors it was around 1uV for 10dB AM SNR on 10M, not impressive even after several tube swaps and coil tweaks. Changed the 1st RF amp to a 6GM6 and it was tweety bird city. Replaced the slugs for discs in both RF stages and 1st mixer and it quieted right down with a .3uv reading.....that I like ;D

Carl

Micas, how about micas??

And, yeah, make me some polystyrenes! :D

                  _-_-bear

If $ were no object, and knowing it would only make a fidelity difference in the modulator at my end, I would go with those high grade caps. Every little bit of distortion removed is a cleaner signal, whether the other guy can tell or not.

For that matter ALL the values listed so far are cheap somewhere.
He asked a question and I answered it.
I don't remember him asking for analysis on those suggested.

Well, Todd did not explicitly ask for an analysis - but the key point was to identify caps for which there is a bonafide need AND also those that can not be readily sourced right now. Otherwise there is no point to having a run of custom caps made, is there?

Unlessl, of course, some person has discretionary funds and wants caps made with their name imprinted, or some other name of choice printed?? Sounds like good fun to me.

Hey, and BTW, this is why i have been heard to say that people who have way too much money - as in discretionary funds - are NO FUN!! IF I had "stupid money" I would have a run of caps made and hand them out like candy at NEARFEST and maybe DAYTON, with an imprint of choice on it.

Maybe... ummm... "AM Condensor Co." or "AM Fidelity Corp."... or maybe "AM iS KING 2010"... etc...

think about people finding that cap in some rig down the line... eh?

... ok, ok, break it up. what are you people looking at???  Lemmee out of here!!  :P

                                           _-_-bear

Ya, instead of "orange drops" we can call'em "Bears".

Yup, I recapped the audio section of my boatanchor with a bunch of .01 Bears!

Sounds good!

Sure, if you find the buck$!!

But maybe "Bud-Din-Loo-Ranes" is mo' betta'? :D

                                   _-_-bear

Btw, tnx for the FB signal report the other night, OM! QSL via the bureau...

yea, get an ESR, ESL plot.  BTW ODs suck

O2 depleted if you want to sell them to fools

What ever became of this?