Posts: 230
Threads: 37
Joined: Jun 2022
City: Marion
State, Province, Country: NY
Hello, I seem to run into bad time with the 75 tube. I have four of these that seem to be somewhat finicky in that they cause noise and fading or no reception even though they test good in my tube tester. My Philco 60 has been the test bed for these. I was beginning to think the problem was elsewhere but I am convinced it is the tubes. Has anyone else run into issues with the 75 tube. I have another radio where I had a problem with the 75 tube and got a good one working in it.
Thanks,
Dan
Posts: 1,256
Threads: 32
Joined: Jan 2014
City: Wellborn Florida
Try cleaning the tube socket Q tips etoh WD 40 deoxit are your friends. Clean the pins on the tubes 0000 steel wool and etoh . Good luck David
Posts: 1,409
Threads: 72
Joined: Oct 2007
City: Linn Creek, MO
Also, try resoldering the pins.
Steve
M R Radios C M Tubes
Posts: 4,862
Threads: 54
Joined: Sep 2008
City: Sandwick, BC, CA
The grid cap is also another weak point with double ended tubes like these, especially the glass ones. Don't forget about the grid cap lead either, I would resolder or replace all of those whilst you are at it.
Regards
Arran
Posts: 1,838
Threads: 117
Joined: May 2008
City: Omak
State, Province, Country: WA
hello Dan
I agree with the others I am restoring my Philco model 38-10T and the tube pins has green corrosion on the pins that it made it hard to remove some of the tubes .
Plus the grid cap leads were stiff and brittle.
Sincerely Richard
Posts: 230
Threads: 37
Joined: Jun 2022
City: Marion
State, Province, Country: NY
All of the 75 tubes in question have nice clean pins. I have replaced the grid cap wire and cleaned the connector but have not done the pins or resoldered. I'll give that a go today or tomorrow.
Posts: 1,256
Threads: 32
Joined: Jan 2014
City: Wellborn Florida
Something to add to the tool kit is the cleaning tips used with a torch. The cost will be under ten at horrible freight.
Posts: 182
Threads: 8
Joined: Apr 2023
City: Roanoke
State, Province, Country: Virginia
dconant Wrote:... even though they test good in my tube tester.
That, of course, does not mean that they are good - it only means tha they are not definitively bad.
Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
https://plymouthcolony.net/starcity/radios/
Posts: 36
Threads: 1
Joined: Dec 2023
City: Greater Boston
State, Province, Country: MA
Flaky grid cap connections have definitely been a problem for me with 75 tubes, among others. After many decades, the solder joint to the grid lead can become intermittent. Agree with others it's a good idea to resolder them.
I even bought several spare 75s "just in case" and now have more than I'll ever need, so let me know if you want an extra.
(This post was last modified: 05-26-2024, 03:17 PM by tym.)
Posts: 16,480
Threads: 573
Joined: Oct 2011
City: Jackson
State, Province, Country: NJ
Dan
What Steve suggested makes sense: resoldering pins and the cap mean just that, resoldering the pins and the cap, not their wires.
Solder over time, under certain conditions, may develop "cold spot". If it is not that infamous "beta tin", which cannot be melted or soldered with an iron, then you simply need to re-flow the pins and especially the grid cap. Often times you will, upon melting the solder on top of the grid cap, will find out un-wetted oxidized copper wire. At which pont you need to clean it, tin it and reflow with tin-led solder.
No guarantee this is it, but I've seen that too.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
Posts: 230
Threads: 37
Joined: Jun 2022
City: Marion
State, Province, Country: NY
Well resoldering the caps and pins saved my 75 tubes. All working good. so now I have some good spares for the future radios that may need one. Thank you.
Dan
Users browsing this thread: 1 Guest(s)
|
|
Recent Posts
|
|
Zenith H725
|
| Here's what the inside of AM IFT2 looked like, and the other pic shows the discs I made to take place of the mica and ke...EdHolland — 07:40 PM |
|
Zenith H725
|
| IF2 will need replacement caps. The arcing was severe enough that the mica is pitted and holed where the HT flashed over...EdHolland — 04:04 PM |
|
My Philco 37-116 Restore
|
| Measuring from center tap like the tube voltages show. Cap 127 is isolated from ground. Cap 127 shown in upper left of p...dconant — 08:05 AM |
|
My Philco 37-116 Restore
|
| Are you measuring relative to the centertap or the GND?morzh — 11:57 PM |
|
Philco 610B oscillator wiring
|
| Still not clear on the wiring interface between the 6A7 and oscillator. After refering to the available schematics and s...Tubester — 07:18 PM |
|
Refinishing Ideas
|
| My 37-116 code 121 is the best sounding radio i have...a daily driver. Since we are talking about "changes". ...poulsbobill — 07:18 PM |
|
My Philco 37-116 Restore
|
| Hello, I finally got brave enough to take the cans off the Expander Unit. Got the grid cap wires replaced and back toget...dconant — 06:50 PM |
|
Zenith H725
|
| I got into the first AM IF can today, and found its mica was cracked. Amazing that it was still working. This one makes ...EdHolland — 06:10 PM |
|
Philco model #20
|
| AHH HA , I got it and can’t thank you fellows enough , when I changed the capacitors I took the advice and did not unsol...onlyrick — 02:24 PM |
|
Zenith H725
|
| Hello Ed,
yes, I like letting projects run for few days to make sure they don't start acting up .
Sincerely Richardradiorich — 01:03 PM |
|
Who's Online
|
There are currently 718 online users. [Complete List]
» 1 Member(s) | 717 Guest(s)
|
|
|
|
 
|
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
