The PHILCO Phorum
Tuning indicator tube - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Various and Sundry Categories (https://philcoradio.com/phorum/forumdisplay.php?fid=37)
+--- Forum: Other Radios (Non-Philco) (https://philcoradio.com/phorum/forumdisplay.php?fid=12)
+--- Thread: Tuning indicator tube (/showthread.php?tid=9129)


Tuning indicator tube - fields 100 - 03-26-2014

I have 6AD6G indicator, which more often than not stays off, occasionally comes on, pretty dim in appearance, but when "on", operates normally and sensitive to the strong station.There is no loose connections.Shows 230 DC at the pin #5 (B+) instead of 180, but this 50v difference is across the board on all tubes- possibly from using 47 and 23uF caps instead of 40 and 20(?)
All other voltage readings are within norm.And I do not have the tube tester.
Time for the tube replacement? Thanks.

RE: Tuning indicator tube - morzh - 03-26-2014

http://www.ebay.com/itm/Pair-of-NOS-NIB-National-Union-NU-6AD6G-magic-eye-vacuum-tubes-/271435238801?pt=Vintage_Electronics_R2&hash=item3f32cd0d91


If no one bids, get them.

Meantime, is the a socket that has a resistor inside or something? Have you checked?

RE: Tuning indicator tube - fields 100 - 03-26-2014

No, no resistors, just straight wire connections.

RE: Tuning indicator tube - morzh - 03-26-2014

If you are sure you have your filament current (can you see the filament glow when the tube is dark?) and your anodes (you do not have to have grid to have it glow) voltages and it is intermittent then it could be a bad tube with some intermittent separation inside.
Of course you have to exclude the possibility of bad socket connections etc.

RE: Tuning indicator tube - rocketeer - 03-26-2014

Yeah, I think before I would do anything else I would run a pipe cleaner thru the socket holes and make sure they are clean, perhaps with a bit of DeOxit of it.

Larry

RE: Tuning indicator tube - vinzer - 03-26-2014

You might try resoldering the pins on the tube.

RE: Tuning indicator tube - fields 100 - 03-26-2014

Done all of the above. I usually change all wiring, remove each pin socket, clean and tighten it. All pins have voltage, albeit 30% higher than normal.
I just found out that original 10watt 1,5K B+ resistor had been replaced with 1.0K resistor, hence the elevated B+ on all tubes, but that should not be detrimental to the glow issue.

RE: Tuning indicator tube - jerryhawthorne - 03-26-2014

Fields, nice to post a link to the schematic. Every radio with an eye tube I have worked on (not your particular tube) has had a 1meg resistor either in the tube socket (mostly) or external and are a source of problems.

RE: Tuning indicator tube - fields 100 - 03-26-2014

@Jerry,
This one does not have any resistors.This particular set up is very interesting and unusual.Unfortunately, I am still having difficulties (or may be just ignorant) with a postings, but the schematic is on the NostalgiaAir and if you don't mind to see it there and let me know what you think, I would appreciate it. It is Airline 04WG803B. Thanks.

RE: Tuning indicator tube - jerryhawthorne - 03-26-2014

Appears your right fields. Not familiar with that tube. Here is a link to the schematic for others.
Jerry

http://www.nostalgiaair.org/PagesByModel/032/M0011032.pdf

RE: Tuning indicator tube - fields 100 - 04-05-2014

Got the new tube, everything's fine, response to the tuning is OK. Thanks for the hint. Have a question on B+ voltage. The 1500 ohm 10W resistor at the rectifier had been replaced with a 1000 ohm. Could be on the account of the half dead E-caps.Now, after recapping, my B+ at the plates is 230v instead of 180v. How detrimental is it for the occasional usage of this set? Thanks.

RE: Tuning indicator tube - codefox1 - 04-05-2014

Tame the B+ to specs. No telling what excess voltage might do to your set. Use dropping resistor's) in voltage divider to achieve factory specs.