[Ron Ramirez]

Thank you so much Greg!

I would say that antenna choke is probably in fine shape.

And thank you for measuring your 2nd IF. Mine, then, is clearly bad since its primary reads 69 ohms. So I need a 2nd IF transformer after all.

I answered your PM and I'll send you another now.

Again, thanks so much,

Ron.

[Ron Ramirez]

I have since learned that the speaker that was in this set is not the correct speaker.

It is part no. 49-152AB. A good friend of mine tells me that speaker is actually used in a 5-R-135. Its field is rated at 2125 ohms, more than double the specified 1000 ohm field of the proper 49-117 speaker.

So, after replacing one tube, some capacitors, all resistors including the Candohm, attempted repair of the 1st IF...it still needs an antenna choke, 2nd (and possibly 1st) IF transformers, an audio output transformer...and possibly a speaker.

Hoo boy.

But I'm committed this far now, so I am going to see this project through to completion.

[Jake Blake]

"Nothing in this world can take the place of persistence. Talent will not: nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not: the world is full of educated derelicts. Persistence and determination alone are omnipotent."    Calvin Coolidge

[Ron Ramirez]

A couple days ago, a CARE package arrived from Wisconsin.

Today, I finally felt well enough to open it.

   

Thanks, Greg!

I then proceeded to remove both 1st and 2nd IF transformers from the Zenith chassis. Then, I pulled the assembly out of the 2nd IF can, attached new wires, polished up the can, and installed it in the Zenith.

Before installation, however, I did make myself a wiring diagram showing how it should be hooked back up:

   

And that is as far as I went this evening.

Plans for this weekend:

• Open up the 1st IF transformer and install new wires on it, polish up the can, reassemble and install in the Zenith.
  
• Install the antenna choke in place of the Philco RF choke.
  
• See if I still have a Philco in my shrinking collection that has a speaker with an 1100 ohm field and a single ended output transformer which will match a 42/6F6 output tube, that I can borrow long enough to try out the radio.
  

Once all of the "new" old parts are installed in the radio, I do not expect it to have any issues.

We shall see...

[NostalgiaRadioTime]

Glad you were well enough to open the package, Ron. Incidentally that's not my Velveeta box! I got some small IF cans in that earlier in the week and just repurposed it as an 'eggcrate' for your antenna choke!

So is it just the output transformer that's bad on your speaker, or the field coil as well? The output transformer shouldn't be too hard to find. I *might* even have something that would work.

[Ron Ramirez]

Well, Greg,

The field coil measures 1800+ ohms, rated at 2125 ohms; and the original speaker for this chassis had a field coil rated at 1000 ohms. (See post #47 above for details.)

So if I use this speaker, B+ will be low. That might be a good thing in a way, given today's higher line voltages, but I wonder if performance will suffer?

I'll send you a PM about the output transformer.

And hey, your box or not, I think using that Velveeta box to give that antenna choke extra protection was a great idea! By the way, folks, Greg padded the antenna choke very well indeed inside the Velveeta box so it would not be damaged in transit. And everything was packed very well, by the way. Great job and I really appreciate it!

[Ron Ramirez]

This morning, I resumed work on the Zenith with the 2nd IF transformer.

Here's a shot of the one Greg sent me next to the set's original IF transformer.

   

The replacement looks just like the 2nd IF from the 6-S-254. It, like the 6-S-254 2nd IF, does not have the spring shield over the grid wire. Yet the part numbers for both of these IFs are exactly the same.

When I added new wires to the replacement 2nd IF and put it back into its (freshly polished) can, I also installed the spring grid wire shield. I assumed there was a reason it had the wire shield originally.

Here's a look after it was installed:

   

A final under-chassis view, or, Take 2 if you will:

   

Yes, I used new plastic covered wire to replace the original IF can wires. Why? Two reasons: (1) the AES cloth covered wire is really too thick for this job; and (2) the original wires were solid, and so are these.

Now for a speaker, with a good audio output transformer, to try this Zenith out.

I quickly found the answer in a Philco 89B cathedral I had bought at Radiorama in Cincinnati back in June.

The K-7 speaker's field coil measured 1096 ohms. The output transformer primary was good as well!

I put together a new speaker cable, using the base of a long-dead 5-pin tube as the speaker connector. I removed pin 3 from the old tube base, installed four cloth-covered wires, twisted the four wires together into a cable, and soon had it all together.

   

more...

[Ron Ramirez]

The moment of truth, Take 2.

Once again, I plugged the Zenith into the Variac.

I plugged my test speaker into the Zenith's speaker socket.

I also hooked up my longwire to the Zenith's A (antenna) terminal.

With the Variac off and plugged into the power strip, I turned the radio on. Then with the Variac set to zero, I turned the knob up slowly. At 90 volts, I could touch the grid cap of the 6F5G and get a solid hum through the speaker.

Well, that was an improvement.

I turned the Variac on up to 120 and...

NOTHING. (Again?)

I began to wiggle tubes. Wiggling/striking the 6K7G had a positive effect and the radio began to play. But if I turned the local-distance switch to LOCAL and back to DISTANCE, the radio would stop playing.

I finally coaxed it to play long enough to shoot this short video of it playing the local Spanish language station:

[Video: https://youtu.be/L9J-VdRCE2Q]

At least now we're making progress!

[Ron Ramirez]

So I shut everything down, turned off the radio, turned off the Variac, unplugged both, unplugged the speaker, unplugged the 6K7G tube (after unplugging its grid cap and removing its shield), unplugged the 6F6G & 5Y3G tubes, and flipped the chassis upside down.

I then carefully tightened the 6K7G tube pin contacts.

I went over each solder terminal of the 6K7G first with the soldering iron and desoldering braid, then resoldered each connection.

Then, using some DeoxIT and one of those little brush things designed for use between one's teeth, I carefully cleaned each tube pin contact.

I let it dry...then flipped the chassis back over, reinstalled the three tubes I had pulled, reinstalled the 6K7G tube shield and then the 2nd IF grid cap lead.

I plugged the Zenith direct into the power strip this time, bypassing the Variac and...

...it roared to life, picking up some stations across the AM band. No more cutting out or dropping out. AVC was working properly. It was fixed!

Since it is up and running again, it was time to reinstall the dial scale, dial glass and related items.

I decided to purchase a new dial glass gasket from Mark Palmquist since the original was in pretty bad shape. I am glad that I did.

I cleaned the dial glass as best as I could.

And the clips holding the dial glass in place...let me tell you, it was much easier removing the clips than reinstalling them! (Just as Greg had said back in post #6, page 1, this thread.)

How it looks now:

   

I'm taking a break from it for a little while. I got a migraine a'ready.

Next step: Alignment.

[Ed Locker]

Good stuff, Ron!

[Ron Ramirez]

Thanks Ed!

So after dinner I aligned the set.

It's no Hammarlund or RCA, but it plays surprisingly well for a six tube radio with no RF amp.

[Video: https://youtu.be/so5jfspbTcE]

This video shows the 6-S-128 as I tune it across the entire AM band, and then part of shortwave band "B".

So that's it for the time being until I come up with a solution for the speaker problem. The Philco K-7 will need to go back into the Philco 89B cathedral (although I'll need to address its rubbing voice coil at some point).

I will admit here that I did buy an 8 inch Grunow speaker yesterday from the auction site, hoping it solves my problems. I may attempt to replace the audio output transformer on the Zenith speaker I have, also, and then see if its higher resistance field coil has an adverse affect on the set's reception, or not. If not, I'll keep the Zenith speaker with this set even though it is not correct. Otherwise I hope the Grunow speaker will work with this chassis.

We shall see...

[NostalgiaRadioTime]

I was busy most of the day working on an RCA 97T, so didn't get to visit the Phorum until late. Wow, it's almost as if I'd been away from it for a week!

You made amazing progress, Ron!

I'm glad those IF cans and Antenna Choke helped make it sing again.

Mark's Zenith Dial Scales are the best! I'm glad you decided to pick one up. It really makes the dial "pop"! Mark also has reproduction gaskets for between the dial scale and the glass.

You're fortunate that the discs on the controls are still intact. Most of the time the two on top are snapped in half from careless removal of the chassis (most common on the consoles).

Yes, those dial glass clips are tricky to get back on again and once they are, you wonder how those little things can hold that glass from falling out! I had the chassis laying on its backside to install the dial scale, pointers, and glass. Really no other way to do it that I could see.

They wised up and went with a much better mounting clip for the dial glass in 1938.

[Ron Ramirez]

Greg- Thanks! But this Zenith has its original dial scale with a new gasket from Mark Palmquist.

The illuminated dial looks pretty good with those warm white LED lamps, eh? Looks just like it has incandescent #44 lamps inside.

It was a busy day spent mostly on the 6-S-128, but I really wanted to finish up the chassis if I was able to do so. I'm glad that I was able to thanks to borrowing a speaker from my unrestored Philco 89B for testing purposes.

The Grunow speaker is supposed to arrive tomorrow. If it doesn't work, I'll be looking for an output transformer for the Zentih speaker I have and we shall see if the much higher field coil resistance has a negative effect on the set's performance. Right now I'm pretty pleased with the Zenith chassis, it turned out better than I expected since it has no RF amp.

[NostalgiaRadioTime]

>> But this Zenith has its original dial scale with a new gasket from Mark Palmquist. Icon_smile

Sorry I misread your post. It was getting late  

That looks very nice for an original dial scale! Usually they are badly yellowed and extremely brittle. The gaskets almost always come off in pieces. Usually those are never salvageable, so glad you got a new one!

[NostalgiaRadioTime]

Ron,

I parted out several speakers a few months ago that had bad cones and open FC's. I *think* one of these output transformers came off of the console speaker from the 6S152. Do either of these look right?