Sir Terry. . . . . .

I am just about to add on to your initial post on this particular radio, but since this thought is a bit apart from my prior musings, I am just going to add it on here.

Along with a later posting to the prior initializaton of this topic last month.

Back at the time you were shunting the I.F. transformers with the different values, I was thinking about some difference in the entirely two different transfomers .

One seems to be using the conventional transformer form with its internal slugs within the coil windings , while the other is utilizing the pot core ferrite / powdered iron of which each core unit is all encompassing the windings, both internally and externally.

There is some bodacious inductive swing possible on that later type of transformer, with its wee enclosed coil assembly.

Sooooo you are telling me of the availability of a modulated signal generator, inclusive of and also wel l l l l above and below the involved I.F. spectrum.

What lets try here, is the additional use of your scope, which I have also noticed your referencing to in the past.
What you will be doing here is making one " hi Yankee dollah" variant of the comon Grid Dipper, in order to answer some nagging question relevant to the present state of your ree-built AYE- EFF transformateurs.

I initially had to go to the "F" version of your unit, since the older basic chassis was showing conventional variable capacitor tuned I.F.'s.

The left corner inset of the schema does show the set using the two different versions of I.F. tranfos. PLUS there is the designation of 75 pf caps being used as the fixed tuning capacitors.

Now for this testing, the radio will NOT be powered up, instead, using a parasitic / static type of testing.

Consult the sets schematic and note the bottom connections and the top connections of the 4 coil assemblies across the schematic.

We will consider the bottom terminal of each winding as being the "cold" side and the top side as being the "hot" side.

Let's begin at the plate coil winding, connected to the plate of the mixer tube. Take scope probe (1x or 10x) and clip on to the best access point of the wiring connecting between the #4 terminal and the # 5 plate of the 12BE6 tube. The scopes ground clip will be going to the #3 of that IF transformer.

Set the scope up with its vertical sensitivity being set to its 5mv vert sensitivity ( or even lower, if you have a Pwemium-yum Bwewed scope).

The hoz sweep speed can be set to its 1us range , since you are not going to be triggering on and seeing individual little 455 wavelets, unless you have a MUCH-MUCH better scope.

Basically, you are merely going to be observing for the overall variation in vertical amplitude of a "green mass" / line.

With your scope now being across that initial winding to be tested, we now need to inject just enough 455 RF into the #4 terminal, and in doing that, we don't want to be swamping it with a very HIGH RF level and throw in error of its readout, along with an overall damping of the Q of the tuned circuit.

The manner in doing that, is by having the signal generators ground connection sharing that common #3 terminal which the ground scope is already on, and have the RF output of the signal generator being loosely coupled in via the wrapping of a bit of INSULATED hook up wire, with it being tightly twirled around that terminal 4 or the wire length that is being used between that IF terminal #4 and the #5 plate connection to the 12BE6.

Basically, we do be , coupling in via a gimmickus capacitorus, with its capacitive variaton being made by the area of its wrap and its tightness.

Initial Observation:

The generator sig out clip gets connected to the internal bare wire end of the fashioned gimmick capacitor previously mentioned , place the signal generator in the 455 Khz vicinity and use no modulation, straight RF coming out.

Then you use the sig gen attenuator to bring up the scopes displayed "green line" vertical amplitude up to a usable /discernable display level .

Then by using the freq adjust of the signal generator, to swing well above and well below 455, you will be able to ascertain the tuned resonance point of that single L/C tuned circuit in that IF transformer.

Swing your frequency generator above and then below 455 to confirm IF you actually are tuned to 455 with that coil assembly. IF it does NOT peak nearby to 455 , but starts incrementally increasing in amplitude either below or above 455 you actually might have acquired transformer resonance waaay down at 228 khz (455 sub harmonic)or waaaay up at 910 khz (455 second harmonic), being attainable with an erroneous shunting capacitor value along additional inductive mistuning.

A 455 signal would pass through either condition, and SEEM to tune in, but being at a severely attenuated level, HOWEVER with unlimited RF strength being available from a signal generator, that makes that error attainable, but less likely perceived.

If the sig tuning is started at ~300 Khz and then rapidly swept up to ~600 Khz , and you very rapidly repeat that up and down tuning action, you then have yourself a crude manual sweep generator, with the the zipping up of that amplitude at resonance being distinctly confirmed.
Finally, you might then stop on 455 and trim in the coil to 455 if it seems to be required.

This now calls for THREE more tests of EACH of the succeeding IF transformer L/C combos in the grid circuitry of the IF amp, the plate circitry of the IF amp and then the detector output circuitry of the final IF transformer winding needing to be done in the same procedure.

One merely shifts the sig gen and scope ground positions to the lower "cold sides" of the sections being tested and the "hot side" terminals of the IF tranfos receive the transpositioned gimmick coupling from the RF signal generator.

Au fin:

Three more sequential game plan plays at hand, after getting feedback, but now also check the 12BE6 oscillator circitry with digital DC metering mode and its - probe connected to cathode #3 and its + probe connected to #1, the 1st grid of the 12BE6.

Note the variance in the negative voltage readings at the very LOW end of the BC band versus the VERY high end of the BCB in expected oscillator level / activity across the total band.

THEN, with the tuning condenser at mid range, and still monitoring the Osc voltage ,take a pocket screwdrivers tip end and short between the meshing axis of the rotor and stator plates of the Osc section of the tuning condenser, if it was oscillating, the voltage reading should drop off.

Pee Ess . . . Tell 'ole dawg . . . Gomer sez Hey! . . and then throw in two head pats and 3 under chinny hooks.

73's de Edd