[Rich K.]

5Y4 tubes seem to be fairly expensive, at least compared to 5Y3 tubes. My Philco 38-3XX uses a 5Y4 tube. Someone had stuck a 5Y3 in the socket, and needless to say it won't work. I was going to jumper the socket (which is mounted in the top of the power transformer shell) so that it will work with either a 5Y3 or a 5Y4, but found that the socket had apparently been made with some of the unused contacts missing. I found this on EBay:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vie...OC:US:3160

Any thoughts, opinions, or caveats? It doesn't permanently alter the radio and I can buy a 5Y4 later if I feel like it, and meanwhile none of the other tubes are affected so my radio will still glow in the dark and be warm to listen (and cuddle up) to! As far as a "standby switch" (mentioned in the ad), aren't they only necessary on things like guitar amps and such?

[morzh]

Rich

here's what I don't get: OK, the one you are trying to buy is 11 bucks (7 plus 4 shipping).

here is 5Y4
http://www.ebay.com/itm/NOS-5Y4GA-5Y4-G-...565e689781

It is 15 bucks total (free shipping).

is the difference that great you consider 15 bucks vs 11 bucks "too expensive"?

[Ron Ramirez]

5Y4GA/GT from Findatube.com:
NOS - $5, used/tested - $3

If you want the ST style 5Y4G (taper-top or, as some people call them, "coke bottle" shape):
NOS - $8, used/tested - $4

The "solid state" tube is probably two silicon diodes soldered into an old tube base with no current limiting resistor, hence the warning to "use a 'standby switch' in the high voltage circuit". If the proper current limiting resistor is used, there is no need for a standby switch. You could make your own solid-state replacement for a 5Y4G...or just buy the tube from Findatube.com .

[Rich K.]

Okay, I've been seeing new-in-box 5Y4 tubes going for $20 or more. I've had some bad luck buying used rectifiers in the recent past, so it's sort of a "once bitten twice shy" thing that I try to avoid when possible. And this time of year, money's tight (the factory I work for closed - without pay except for Thanksgiving day - all of the holiday week, and will be doing the same for Christmas and New Years weeks). So, after bills, Christmas gifts for my kids come next, THEN radio stuff if anything's left over.

[37silverstreak]

Hi Rich,
My thoughts would be it's simply a matter of personal choice. If the device is easily removable and doesn't require circuit changes to work, go ahead and try it! It's not expensive and it is your radio after all.
My personal preference is that I probably would not use one as I don't like the idea of having a solid state device running in my tube radio. Not because it wouldn't work well, but just because it isn't an original type of component.for the sake of keeping things original, but again it is simply a matter of personal choice.
As for using a standby switch, I am not an engineer, but my guess would be it's because seeing as it is solid state and not a tube, when powering it on you would get instantaneous high B+ voltage to the plates of the tubes before the filaments would have time to warm up. This instant high B+ might act like a magnet and pull the coating from the cathode of the higher voltage tubes and damage them. a tube rectifier would gradually increase the B+ and allow the other filaments to warm the cathodes and reduce this effect. But that's just my amateur thoughts, I'm sure there are lots of guys here who are a lot smarter than me who will know the answer.
Whichever way you go, I hope you can enjoy your Philco 38-3xx

[Ron Ramirez]

Rich, I would not recommend Findatube.com if I were not a satisfied customer. Bob Dobush (Findatube's proprietor) is a straight up, stand up fellow...he will treat you right...you can buy from him with confidence. In fact I have a few 5Y4GA's here that I bought from him for some of my 1937/38 Philcos...all used because I'm a cheapskate at times...all A-O-K

I am sincerely sorry about the money situation. I've been there. Still not rich and never will be, but God has blessed, and provided, and will provide. Take care of your kids first, and I know you will.

[TA Forbes]

+1 Bob has always done me right, his NOS tubes always test NOS.

I have heard/read discussions about solid state rectifiers, it seems that they are mainly applied to tube tester application due to plate-balance issues.

[Chuck Schwark]

Bob is a standup guy.

Chuck

[klondike98]

+1 on findatube.com and Bob D.

[Arran]

I don't know why a 5Y4 would be that expensive, I've bought good testing #80s for less then that, basically the same tube as a 5Y3/5Y4 but with a different base. In my case I am on the lookout for 5Y4GTs as they don't cook the eye tube cables used in Canadian RCA A23s and sets with similar chassis, the ST style ones do. You don't really need a NOS tube anyhow, used but testing good is fine with a rectifier, in fact they can even be a little weak and still work. In the past I have installed jumpers between pins to make a 5Y3 work in a 5Y4 socket, one of the plate pins does not line up and one of the filament pins does not line up.
If you go with a solid state substitute it might be a good idea to add a current limiting thermistor in series with the output, maybe also a fixed resistor too is the B+ is a little high. The directly heated tubes are almost instant on but still need to warm up, the thermistor simulates that.
Now if you want much more of a replacement problem try a Rogers/Canadian Majestic/Deforest Crosley radio with a pair of 2X3s or 2Y3s. Unless you are very lucky you will only find good used 2X3s, I've never seen a NOS one.
Regards
Arran

[37silverstreak]

I agree with the others. I've dealt with Bob D. for tubes several times and have been very happy. great guy to work with!
Kevin

[morzh]

And I also will add my agreement with the above: Bob is a good guy, stands behind his merchandize and service, and his wife provides a very good response time when you need to discuss the payment/shipping arrangements.

[codefox1]

Totally agree, Easier to make enemies than friends in this hobby. I don't sell tubes. Now then please try to determine why you need the replacement tube, i.e. filter capacitors, crispy resistors pointing to further problems, etc... And when you think you are ready use a variac or a dim bulb tester, and I like to use an old fashioned analog milliamp meter, say 500 MA range for a small radio, to check out the B+ current during initial testing. Be ready to shut things down very quickly. Best!