I can hear my signal generator coming in on a tuned frequency (signal generator and dial on radio match) with 2 of the tubes removed. That would be 1RF and 2RF removed. My signal generator hooked to a pin on 3RF.

Now if I “HEARD” you right, you have the sig gen into the INPUT circuitry of the THIRD RF, therefore the 1st and 2nd wouldn’t
come into play, being in FRONT OF that RF signal flow path.


How’s about leaving a “ to be evaluated” 24 in that 3rd RF slot and bring the mod RF from the signal generator down to a just
perceivable weak detected audio tone and lock that reference into your mindset and then sub in each of the other 24’s for a
warm-up and judgment against that initial criterion . (OR that of another 24 in that tube sequence , in case there was a
decided difference between a tubes amplification performance. . . . .2 tubes out of 3 should let you evaluate a norm.


The e e e e e n you can phase in a 24 tube for the 2nd RF slot and move a greater attenuated RF signal input to that point and
eventually progress to the full 3 RF stages complement of the set, to see if there possibly are circuitry problems or alignment problems
in the frontal stages.

Sir Neal:


What you have yourself there is a Tee-Ruhh-Effff receiver, not a Super Hot Rodent, such as you have been dealing with before.. . . .no local oscillator. . .and the "carrier" is the feeble received signals RF presence.

This unit is dependent upon taking the wee RF signal at the front end and progressively amplifying that feeble level thru multiple cascaded Variable tuning condenser / coil combinations.

Your set has a set in each of the RF amps 1st grid circuits stages and then thru the final tuned unit at the detector stage.

Since you already receiving stations, we know that all you will need to do now is a tuning in of all of those 4 tuned “sets” to a common frequency.

I can’t see that units sets of tuning condensers vanes and see if any logarithmic tapering of the vane shaping is involved, so lets just go with eyeballing the vanes rotary position and see that the units ganged rotors are then set at a 90 degree plane to the frame of the tuning condenser. . .ergo mechanical mid range and “center frequency”.

Now go to the front of the dial scale and see what the dial scales current frequency calibration is reading.

Whatever that is, will be the frequency to work with on setting your tone modulated signal generator to.

You will be keeping your sig gens RF output level at such a low level, to the degree such that you can just barely ascertain its received audio presence.

You will then be progressively re- attenuating as each stages gain improves.

Initially start at the pre determined frequency and adjust the last. . .4th L-C clusters tuning condenser trimmer for max audio , with your Sig Gens RF input lightly coupled in from from the earlier stages plate circitry.

Then move the RF input one stage back towards the front of the receiver and trim in the 3rd L-C cluster in the same manner previously.

Then move the RF input one stage back towards the front of the receiver and trim in the 2nd L-C cluster in the same manner previously.

Then move the RF input one stage back towards the front of the receiver and trim in the 1st L-C cluster in the same manner previously.

As you get closer to the very front end you will find that the RF input coupling on the frontal stage can be as low as the “gimmick” capacitance such as is presented by the clipping of a signal generator clip onto the INSULATED wire on the previous stages plate wire circuitry .

After sig injection disconnect and tying in a decent antenna for evaluating on air. . . . those stations should now be rolling in.

With you then havingthe 4 different sections of the tuning condenser then all tracking in unison to that tuned in station and amplifying the selected frequency with the combined level enhancing “flywheel effect” of a tuned resonant circuit and the cascaded tubes amplification.

Wow, EDD...thanks a bunch for giving me guidance. Now I hope that I have the brain power to interpret what you've written. I appreciate all the time you took to give me a proceedure and enlighten me on just exactly what I've got here. I will start the proceedure soon and if I get stuck I'll post questions...Neal

It didn't take me long to get stuck. The center frequency is 800kc.

Nope, that’s not getting stuck, its merely finding that the center mechanical and and the center of the BC band on that unit of yours is not the usual 950-1050, as found on a smaller “two lunger” superhets tuning condenser, but being 800, on that mammoth
capacitors set's bank of your set.




Ed: Were my questions to basic that you've given up on me?...Neal


Heeee’s Baaaack. . . . .Nope, over the weekends are just not the best time for my WWW communicating. . . . PLUS I didn’t have all of my research info until just now.

Is the detector tube considered a stage?



Yes, the detector stage is the fourth tuned circuit down on the sets circuitry.



What do you mean by "with your Sig Gens RF input lightly coupled in from from the earlier stages plate circitry". Do you mean 1rf pin 2?



I was merely referring to keeping the injected RF test signal at an absolute minimum, such that the RF amplifier circuitry is not swamped with a signal level and thus makes the tuning adjustment broader; with you then not being able to set the tuning more precisely, to then be optimized for the most sensitive adjustment possible.


I was basically referring to the use of the typical alligator clip at the “hot” end of the RF output of your RF Signal Generator and it being merely clipped onto the INSULATED wire of that PREVIOUS stages plate wire connection. That resultant "gimmick" capacitance, along with the attenuator of the sig gen, should then let you set the RF injection level way on down into the just barely perceived presence of its 400/1000 cycle tone modulation thru the speaker.


IF there is any possibly of spurious oscillation, by virtue of a previous RF stage also picking up the input test signal, merely unplug that tube until you get the tuning of that stage done and then are progressing on towards the front of the set.



Is the L-C cluster one of my 4 adjustment bolts?...Neal

NO, with that terminology, I am referring, in general, to the four sets of coils and their associative companion tuning capacitor sections that are associated with the 4 tuned sections in the frontal RF portion of your set.


Refer to accompanying GRAPHICS. . . as the bottom attachment.


(sic)

I have an intemittent open/short in the audio signal that I have to find before I can go on. By tapping ever so lightly on the chassis, it will loose/gain audio. Could it be a component? Or is it what I just mentioned, An open or a short. My come and go is more prevelant around the tuner.

Looks like that final little aspect is EXCLUSIVELY for you to be zeroing in on. . . since you physically have the set. . . and I am DEAF. . . .BLIND. . . .AND DUMB. . . (and that's HEEEEAVVVVVY ON THE DUMB aspect.)


I would be doing a light. . . . and then progressively stronger. . . tapping, flexing, bending and pulling in the “sensitive area”
which you seem to have already located.


A common associative problem:

Check the tuning condenser phosphor bronze tensioning and pressure contacting strips associated with the grounding
of the rotor sections mechanisms, to the frame of the tuning condensers sections.

In some cases, they can be silver plated and have a poor / intermittent contacting action thru some degree of rotation due to a heavy black AgO2 build up. . . with time and environs.

(Afore times, nesting rodents urine depositions, can also take the balls off of a pool table.)


Also with time, and much use, they just loosen up and loose their tensioning, along with a resultant intermittent connectivity.

HOWEVER, on looking at the only photos which I seem to have for that unit it looks as if you will be dependent on the gang to gang tuning being dependent upon how it currently is mechanically positioned.

On the first generation TRF’s they had separate tuning condensers for each RF stage, on yours we can see that the units are ganged inline and all acting as one combined cluster instead of individually tuned units.

ALSO there is no provision for mechanically changing their rotational coupling position on that common shaft.

I see no associative, adjustable trimmer capacitors used in conjunction with each stage.

On some sets they had different set screws around an end vane so that different segments of that end vane could be moved in or out for increasing or decreasing the contributed capacitance on that final end vane.


NOW in looking at the figures below, it does look as if all of your rotors are using a common strap across the rotor segments[YELLOW ]. . . .EXCEPT. . . . that end vane which could be moved in or out a bit in its proximity to its companion end stator vane.

Now, I can’t see that end rotor vane in order to see if it is slotted up into segments, but I would suspect so.

If so, this balancing adjustment between different sections would almost be a factory adjustment during final tune-up.

ASIDE:


If attempting to do that tuning myself, I would be connecting a Boonton RF voltmeter onto the end circuitry in order to get a visual indication of the mechanics adjustment versus the RF effect via the voltmeter readout. . . . .it being , much, much to small to determine aurally.


PLUS that fine adjustment of a rotor plate segment by a “micro” bend is one HECK (x10 !) of repetitive task to locate and optimize a final position.

I also possibly might experiment with a 2-10pf trimmer placed across each tuning stator and then seeing if any improvement could be acquired, an alternate would be the adding of an adjustable slug to each RF transformer core, but somehow, inside those cans, I would be expecting to see each of them wound on a big old 3-4 to 1 inch coil form.

Overall, seems like to me, that you will be settling for what matching of tuned circuits you have on that tuning gang, being as it is currently.