(Note: On my puter screen the wording in this posting far exceeds the right edge. I don't know why...never had it happen before.)
My job, my Heathkit transceiver repairs, Christmas shopping with the wife, wrapping, packing and shipping what she bought have
all been putting a severe crimp in my restoration style. But I finally found some time to start checking out the coils in this dog.
Here they are:
A. Primary and secondary windings of the power transformer
B. Local oscillator.
C. Primary and secondary windings of the IF transformers (IF cans).
D. Primary and secondary windings of the audio output transformer.
E. This radio has seven pushbutton tuning coils.
F. Antenna coil(s).
G. Speaker field coil (found on electromagnetic speakers).
H. Anything else that remotely smacks of being a coil.
Let’s start with the power transformer primary winding. The large arrows are the multimeter red and black lead connection points.:
This is the on/off switch. It's operated by pushbutton:
It’s difficult to make out on the schematic, but I think we should get 12-ohms for this reading. Hey...10.3-ohms suits me just fine:
The secondary is center-tapped, meaning it’s divided into two halves…upper and lower. We’ll first measure the entire winding…plate to plate on the #84 rectifier tube, pins 2 to 3:
Looking good. I like it:
Now let’s individually measure the secondary top and bottom halves, pin 2 then pin 3 to the non-grounded end of the Candohm resistor (circled in blue on the schematic and green in the chassis). The grounded end is circled in orange.
The combined readings should of course add up to almost 272-ohms:
129-ohms plus 142.5-ohms equals 271.5-ohms. We’ll take that:
Last up is the power transformer filament winding, pins 1 & 5:
We have continuity, but it’s much higher than the "less than .1-ohms" value shown on the schematic. I’m not sure what to think about this:
At least the power transformer isn’t fried (a big load off my mind), so let’s move on to the pushbutton tuning coils. There’s seven of them. Each should read only a few ohms.
The schematic shows that one end of each coil is grounded, so the black lead was simply clipped to the collective ground wire (yellow arrow). The red circles show the connection points for the red multimeter lead:
There was a little bit of variance, but all seven coils are good to go:
We’ll finish up with the audio output transformer:
The secondary winding comes first. The transformer’s metal frame is riveted to the chassis, thus providing the ground as shown in the schematic, so the black multimeter lead is connected to the chassis. The red lead is connected to the terminal in the red circle:
Generally speaking, audio output transformer secondary readings are fairly low.
We can live with this:
The center-tapped primary will be the final reading for this posting. The striped wire in the pic is the centertap. From there to the black wire is the bottom half of the winding. From the striped wire to the white wire is the top half:
And the bottom half reading is (ignore the number one).
Uh-oh...I'llllllll be back!: