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Zenith 7H920 Restoration - Printable Version

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RE: Zenith 7H920 Restoration - MrFixr55 - 01-05-2026

Hey, it weighs less than an RCA Livingston, and amazingly, sounds almost as good. (The 1R81 Livingston is a transformer powered set with 6V6 output and 8" speaker.)

RE: Zenith 7H920 Restoration - radiorich - 01-05-2026

Hello MrFixr,
That RCA is one of the radios on a short list !
Sincerely Richard

RE: Zenith 7H920 Restoration - morzh - 01-05-2026

   
   



Coincidence?

RE: Zenith 7H920 Restoration - morzh - 01-05-2026

[Video: https://www.youtube.com/watch?v=EtSYNt_Adaw]

This is the radio after assembly and FM alignment. Still there, in the basement, no FM antenna. BC receives on the internal loop antenna.

RE: Zenith 7H920 Restoration - morzh - 01-05-2026

And, as mentioned, the brackets.

The aluminum (1/16" gauge) sheets came today.
Then, saw-cut-bent-cut excess-deburr.

Not exactly your production quality, but will do.

   
   

This is how it looks:

   
   

OK, I am done with it.

RE: Zenith 7H920 Restoration - morzh - 01-11-2026

I went ahead and made (a bit late, I used an approximation of it: I did not have clips and plugs to make it)an adaptor for a DMM to emulate the one that they recommend for Zenith FM radio alignment.

The adapter (that was supposed to work with a VTVM) consists of:

- a coaxial shielded cable. 
- The probing end: 2M resistor in series with the central conductor, with a flexible wire (I used silicon jacketed wires for all terminations) and a hook clip at the end.
- The shield extends over the resistor and the wire between the end of thecable and the hook is fairly short. This is due to the requirement in the service bulletin that the probe ends going into the radio be shielded.
- The shield itself is soldered to a flexible wire with a small alligator clip, to hook to the chassis.
- The end of the cable is heatshrunk, for teh length of 1Ft or so, to not short anything inside the radio.
- The meter end had the central and the shield connected to two banana plugs with flexible wires.

The cable is fairly long as I noticed the DMM, in close proximity to teht radio, induces noise. And this is a good one, a Fluke 189.

The whole cable
   

The probing end
   

The DMM end
   

The DMM with the cable
   

The DMM with the cable probing shorted, showiong 2M.
   

So, the next time I need to align an FM...especially a tabletop Zenith one...

RE: Zenith 7H920 Restoration - MrFixr55 - 01-11-2026

Nice job on the brackets. Dad worked for Grumman Aerospace. Their favorite saying was "It'll look fine at 30,000 feet.

RE: Zenith 7H920 Restoration - morzh - 01-11-2026

Exactly. Actually, one of the 4 looks decent. The one in the photo.

If the grindstone I inherited from dad did not throw some kind of paper around, and if I had a sandblaster, that one could look almost professional. Icon_lol

RE: Zenith 7H920 Restoration - DaleHCook - 01-12-2026

(01-11-2026, 07:50 PM)morzh Wrote:  The cable is fairly long as I noticed the DMM, in close proximity to teht radio, induces noise. And this is a good one, a Fluke 189.

That is a major reason why my shop includes some analog meters, including an HP 427A Voltmeter (actually an AC/DC voltmeter with 10 meg input impedance, and ohmmeter) and a Simpson Model 260 Series 6 VOM.

RE: Zenith 7H920 Restoration - morzh - 01-12-2026

Dale,

I am not sure if the HP is not just a passive VOM, but the Simpson 260 is, so it won't do here. HP might if it is an active (amplified input) type with high input impedance.

RE: Zenith 7H920 Restoration - DaleHCook - 01-12-2026

The HP 427A is an FET input amplified AC/DC voltmeter (good to 1 MHz), and should work fine for your purposes. It is one of the two analog meters which I use the most in the shop. The other is my HP 400E AC voltmeter which is good to 10 MHz. My primary shop meter is a Keithley model 179 4-1/2 digit true RMS bench DMM, which is my only instrument which goes out to a cal lab.

The Simpson 260 is used only for my older sets. Those were built before the advent of the service grade VTVM (the Rider Voltohmyst) in 1939. If I really want to get old school I own a ca. 1935 Triplett model 1167-A set tester, consisting of a model 1125 VOM and model 1166-A free-point auxiliary set tester in one cabinet.

RE: Zenith 7H920 Restoration - David - 01-15-2026

.pdf zenithh723z1.PDF Size: 301.63 KB  Downloads: 138

Found this some were on the net. David

RE: Zenith 7H920 Restoration - morzh - 01-15-2026

David


Good document.

And, I kinda overlooked the fact that they have a small cap connected to an AC line that could serve as an FM antenna.
Will try it.