Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Troubles With FM Alignment On 46-480
#1

AM aligned beautifully. FM has no reception at all to begin with. Steps 1 and 2 of FM alignment go well but in step 3 C32 is very unstable, or maybe eratic is a better word, and just by touching it with my alignment tool increases reception slightly. When I am able to get a somewhat stable reading and proceed to step 4, I'm seeing no changes at all throughout this step of the procedure. I guess pull the trimmer can out and check trimmer C32 to start with? Other ideas would be greatly appreciated.
#2

sometimes, I have found the pushbutton contacts were not making good connections in some cases. Also, sets that use the loctal-type tubes & sockets were notorius for not making good connections unless the pin connections are all cleaned really,really well. I usually scrape the loctal tube pins carefully with a exacto knife to make sure they get good connections all around the tube sockets (bright shiny clean). Just tryin to help with a couple suggestions of sometimes overlooked culprit-probs in sets that use the local-type tubes. Icon_wink
#3

Icon_biggrin Thanks Tex. When I put this thing together I cleaned all the Loctal sockets along with the tube pins themselves. Well today I pulled the tubes and cleaned the sockets again with a small wire brush. Similar to a gun barrel cleaning brush but smaller. I also took a piece of emery cloth to the tube pins. Still didn't work but when I wiggled the tubes it would work again. So I took the tubes and actually bent the pins out just a hair and reinstalled them. Seems to have good FM now. Who ever invented the Loctal and what good is it if they weren't dependable. I've had trouble with them on another radio. Anyway I aligned the radio and it works great now. Thanks!
#4

...glad you bent those tube pins for good connection! I forgot to mention that! The best way to "clean" the tube pins on loctal tubes, is by actually hand-scraping each individual pin with a exacto-knife blade till "shiny".
Most usually, wire brushes, emory cloth, dont have enough cleaning power when dealing with those type tubes! It takes "force" to get those pins clean(scraping) again for proper contact with the loctal-sockets! It is also a good idea to spray WD-40 on both the tube pin tips , and sockets to keep the loctals-connections (all) from corroding again in the near future, or they will in high-humidity type climates! You bet, bad tube design invention from the get-go,period!!
Anytime you have a prob with any radio using loctal-type tubes after full re-cap, most usually, the residual probs of alignment or etc, can be traced back to the loctal tube design!
Ive been told by several WW2 USAF radio-techs, that the loctal-type tubes were originally designed by "JAN" ( IE: joint Army/NAVY) to be used in the WW2 era aircraft Radar systems,etc, and lots of them failed at very in-opportune times of warfare!! Im sure lots of Radio mfgrs of that era snapped the leftover JAN type loctal type tubes up to be used in "receivers" only for a very modest/ quantity price back in those days to be used in home type radio receivers! Zenith also used lots of the loctal type Govt leftovers in their production runs of tube radios also, as well as most other mfgrs! Now, all us vintage radio techs get to deal with them!! Icon_wink




Users browsing this thread:
[-]
Recent Posts
trying to identify this wire type
Greetings Phorum members, Hope you can help me identify this type of wire in the photo I have attached.  I am not sure ...georgetownjohn — 01:53 PM
Philco 60 Squealing
All correct shields must be in place, all tubes correct no subs of any kind. Check any soldered, riveted ground conne...Chas — 01:24 PM
Philco 60 Squealing
I have recapped and replaced out of tolerance resistors and so on. Radio plays nicely on fairly strong stations. The pro...dconant — 10:55 AM
Philco 46-420 Code 121 Reception issues
Welcome Eric, I agree with Bob and far as the two main electrolytic filter capacitors did you change them yourself or w...radiorich — 11:43 PM
Philco 46-420 Code 121 Reception issues
You mentioned the Philco manual and going through the check points...just to be sure we're on the same page here's the m...klondike98 — 08:13 PM
Philco 42-1008 conversion kit
Interesting. I haven't seen that before.klondike98 — 07:02 PM
12' Philco
Yes I had looked for it on the web as well some time back and could not find it. I was glad to see it turned up in Ron'...klondike98 — 06:59 PM
Shadow Meter Bulb
Now if you had a set with a tuning light then the bulb type is important to the circuit, some sets used those prior to t...Arran — 04:58 PM
Shadow Meter Bulb
Ok. Thanks for the correction.RossH — 03:09 PM
Model 28L
For 28 you will probably need to buy a Hammond 125CSE. Or any of the series of the power you need, with SE suffix. Then ...morzh — 02:09 PM

[-]
Who's Online
There are currently 7160 online users. [Complete List]
» 2 Member(s) | 7158 Guest(s)
AvatarAvatar

>