[Phlogiston]

First, I put this here since I can't think of a Philco that uses an 01A.

I just looked up 201/01A postings on E-Pay. It looks like prices are up since the low around 4 years ago. Then it was not uncommon to be able to buy these for $10 - $15. Looks like it is $20 - $25 now. One thing you can be sure of - they aren't making new ones.

There is plenty of history on the 201 online so some research should be done, if you are interested.

I have more than enough UX201s to last a long time, especially considering that the plastic base, long pin tube was really only original equipment for about a year with the previous versions running back to about 1920. And since I try to put the original brand/type of tube in my restorations - well, that is why I have plenty.

But, most people only care about the radio working - and being cheap (me too).

I have thought about this for a while and it is a sure thing that I am not the first. Here is how it goes - build a replacement for the UX201/01A for less than $2.50.

You are gonna' need a 4 pin base like off of an 80. Depending on your radio, this base may or may not need to have the side pin for the Bayonet/UV base - depends on how old your radio is. Then a standard 7-pin miniature socket. These should both be available from your junk drawer.

Then look in your tube stash for a 6C4. I picked this tube for it's characteristics - basically it is 1/2 of a 12AU7 and it is called a power triode by RCA. If you don't have one, E-Pay has some for about $1 some NOS. I just bought 15 about half of them NOS for an average of $1.10 - Sorry, there will be more.

Then 4 wires and a jumper will connect the 2 sockets/plugs. Connect the 7 pin socket, pins 3 and 4 to the big pins, pin 6 goes to the small pin on the right (Pins up, big pins closest to you) and the plate to the remaining small pin. Then place a jumper between pin 3 (fil) and pin 7 on the 7 pin socket. This is the cathode connection.

To test as a 201 use the same settings as an 01A but you will need to lower the bias from about 48 to near 0.

In testing this tube works great as an audio amp including a 171 or 112 . I tested it in my AK 20 in all positions with setting as they were for the 201s and it worked great as a detector and audio amp improving tone and level some and about the same as the 201 in the RF amp sockets.

BUT, BUTTTT it is a 6V tube. Yeah, it doesn't matter. It takes about 10 seconds to warm up. BUT, BUT, BUT the cathode will be damaged - well if it goes to "sleep", just run it at 6V in your tube tester for a while. In reality these tubes were often run at low filament voltages to keep noise down in audio circuits and as a way to get bias for finals - look up some of the Fisher amps using the 12AU7 and 12AX7. It will be fine.

Also it only draws .15A of filament current. This will make your power supply/battery happy.

   

I potted this one in tar, but I think I'll use resin on the next one.

Not sure how a radio with 5 of these will work.

I'm going to post this on my blog soon, so get your 6C4s before the run.