Cant really take a pic of the variable caps (inside the SECONDARY IF can). But its a bit crackly when i try to adjust these 2.....
So, i took a shot at it.... RF gen set to 460, dial set at 520, cap off of 1st IF.. .1 cap in series with line to grid of 1st IF tube, and.... SILENCE... Didnt hear a tone till i bumped the dial of the SIG GEN up to 500.. and proceeded to peak the If section.. It did improve the performance in reception. Just curious if the .1 cap in series is affecting accuracy, or is something in the radio WAY OUT??
Ah - I know what you mean now. It shouldn't matter too much if they are noisy when adjusted.
With mine, I forget if I made a direct connection with the signal generator, or just let it couple using a wire connected to the generator, and arranged near the first RF and allowed stray capacitance to couple it. You can certainly try this, and see if the generator can be heard. Or connect to the antenna and let the signal bleed through from there. Keep the level low enough it can just be heard, and then peak - this way, you are less likely to be confused as the AVC shouldn't be too active.
I did go through the procedure, and found my tuner is a bit out of whack. Had to compensate the RF GEN. to get the tones i needed.
Even though my tuner positions are still askew, i did manage to increase the radios sensitivity and performance. Even the shadowmeter is alot more active as i tune stations in.. Starting to wonder if the tuning gang was molested or do i have something drifted?
Meanwhile, im getting signals through all the SW ranges depending on time of day...
On a curious note, how warm should the PT get under normal operation?
Nothing alarming, just curious, runs cool with 80 removed.. After a few hours, its quite warm, but i can rest my hand on it. Just wanted to make sure this is normal... Its been awhile since ive ran an 80 yr old on a regular basis.. Thermometer reads 110 degrees on transformer and slowly rising... Is there a maximum operating temp for these?
Steve
(This post was last modified: 03-17-2019, 12:29 AM by Stall-U-Rated.)
So i placed a meat thermometer on top of the PT and let the radio run all day.. 115 degrees near 120 seems to be the run temp.
Sound about right, or is something overworking the transformer?
I think you should be fine. If I recall correctly, total power draw for the set us of the order 120 to 130 Watts (it is in the service info). If you can measure the line voltage and current, this would be another good indicator that things are fine. Also a check of voltages caĺled out on the schematuc.
So i may have shot myself in the foot doing a second alignment on this radio..
I had an IF adjustment (2nd IF can) cutting out during adjustment, so..... I powered down and gave it a shot of contact cleaner. Let it dry 30 min, and warmed it up, and tried the loose wire near the 1st IF tube coupling procedure. Although the dropout subsided, i dont think im getting full potential since i sprayed it...
My question is, do the can covers come off pretty easy to inspect the IF adjusters? I see 2 screws on top but i just want to make sure im not gonna drop a nut into the works by removing the top screws.. Any experience with the workings of these cans and adjusters are welcome..
If it is like mine, with three round IF cans, you must loosen and remove the screws on top of the cans - these actually hold the ceramic bodies of the trimmers. Nothing will fall inside. You also have to remove the screws holding the cans to the base. All three cans will come off together, exposing the coils and the trimmer bodies. It should all go back together the same way. Be extremely careful when this is opened up.
I can look at one of the trimmers, if you want, as I have a set of these bought as part of a junk set someone was parting out... That will let me investigate what cleaning of the trimmer would be possible.
Thanks Ed, a picture would be great. Radio is doing better today, but i would be curious to see underneath the cans just in case the need to clean them becomes urgent.. Didnt realize these 3 cans were connected together. Learn something new everyday
OK Steve, here is what is hidden in those mysterious cans:
The screws securing the trimmer to the top of the cans run into the brass bosses seen here:
These are the trimmer screws:
And the two plates of the trimmer, sandwiching a piece of mica are underneath:
Removing the trimmer screw all the way won't cause a mechanical explosion:
As can be seen from the last picture, the screw is floating, electrically speaking. Any scratchiness (dirt on the threads or in the brass insert in the ceramic) is only a factor when you're connected to the set while making the adjustment.
So it would seem by your pictures, i blasted the screws and the cleaned the ceramic a bit..
Since the radio is doing better a day after im gonna just count my blessings and avoid messing with that section any further unless an issue arises. I think ive gotten the most i can out of tuning that section as im gonna get. Thanks for the pictures, theyre helpful to me and anyone else following this thread
Meanwhile, theres more sections to tweak on. Still trying to get my dial accurate...
Ran across an old pic of that diner i mentioned earlier in the thread and pretty much confirmed the source of the radio i have.. The lack of speaker material and the NON stock tuning knob i spotted when i enlarged the original pic confirms it...
Just funny as heck when i consider the fact i used to eyeball this radio every time we had breakfast there, "ide like to get that running" crossed my mind while i was eating my omelette.. The odds it took to end up in an nearby city yard sale years later. And to end up on a table of a place we already checked out earlier that morning and was passing by on our way out of town after finishing looking around for the day.
