Capacitor recommendations.
 

I have decided to take the plunge, and bought an unassembled tube radio kit with the goal of putting it together. Hopefully I'll have plenty of opportunity to learn all sorts of new things about how to work on tube radios along the way.

One of my first lessons is figuring out modern equivalent capacitors to replace the now very NOS capacitors that came with the kit. From what I understand, it should be a given that I'll replace the paper capacitors with modern ones, I just need to figure out what types to replace them with.

As for the electrolytics, I'm not sure if they need to be replaced or not. Even if they seem ok, should I just order new ones? It seems like it would be nice to have all new parts in a "new" radio, but if it's really not necessary to replace an electrolytic, it would save some time (I'd have to unmount the electrolytics from the chassis, since this kit made it easier for the hobbyist be pre-mounting many of the components).

I'll list all of the capacitors (including the electrolytics, which I'll note as such), and ask if you guys agree that I've picked the right capacity replacements. You'll note that the catalog I looked through didn't have exact voltage ratings, but if I understand my research correctly, it's safe to exceed the original voltage specification with the replacement as long as you stay within +/- 20% of the original capacitance specification. As I understand it, I have a little more lattitude with electrolytics than the non-electrolytic capacitors, so I wasn't as worried for electrolytic #2 below when I couldn't find anything closer than double the original specifications.


Thanks,
Joe


Here's the list:

1. Electrolytic #1: 40.20 uF @150V.
Choice 1: 50/50 uF @500V (multisection)
Choice 2: 80/40/30/20 uF @525V (multisection)

2. Electrolytic #2: 10 uF @10V. Replace with 22 uF @25V

3. Paper #1: 0.05 uF @400V. Replace with 0.05 uF @600V

4. Paper #2: 0.04 uF @50V. Replace with 0.047 uF @400V

5. Paper #3: 0.01 uF @500V. Replace with 0.01 uF @600V

6. Paper #4: 0.005 uF @500V. Replace with 0.0056 uF @600V

7. Paper #5: 0.002 uF @500V. Replace with 0.0022 uF @600V

8. Paper #6: 250 pF @500V. Replace with 250 pF @500V

justradios.com has caps. I order mine from there all the time, never had one fail yet.

Yes I can recommend justradios.com, we order from there for our shop.
You do not need 500v. electrolytic caps for this application...I would use 2, 47 mfd. at 160v. or a 47 and a 22 at 160v...they are a lot cheaper. Just mount a terminal strip if needed to mount the individual caps. We just leave the old electrolytic cans on the chassis and mount the new caps underneath. These 160 volt caps are pretty small. Make sure that you do not ground the power line ground to the chassis if the set is transformerless and isolates the circuit ground from the chassis.
It would be good to replace the electrolytics as these can deteriorate too, and while you're at it you should just go ahead and replace those caps.

Your other cap substitutions look fine.

I am curious to know where tube kits are offered and if they are reasonably priced. It's sure that I don't need any more radios, but it'd be nice to play with a kit again.

I got my kit on eBay. Just plug in "tube radio kit" into the search engine and you should get a few hits. It takes a while of watching the auctions to find just the right kit, but they do surface regularly.



Joe