[MrFixr55]

For these Zenith AM/FM sets that use selenium rectifiers I have merely swapped in a 1N4007. I upped the filter cap working V to 160 or 200. I have not found an issue. I think that the chassis is hot because it is an AM-FM radio and using caps to make it a "warm" chassis may greatly affect FM performance. I have 4 of these Zenith sets, the H725, the 7H820, and 2 from the early 1960s. All of thes sets have interlocks. The newer sets have no exposed screws, and I think that the knobs are captive by their clips and very difficult to completely pull off (tools required) I also have an RCA 8X71. All of these are hot chassis sets. IMHO, it is best to move the power switch to the hot side, add a polarized plug and use screw covers on any exposed screws on the older units.

Someone made mention of the lack of 3 pin grounded outlets on older houses. All US wiring has the "neutral" at ground potential. On all but the oldest outlets (Pre WWII), even ones without grounds, the holes are not equal in size. The longer slot is neutral (or is supposed to be).

[EdHolland]

The radio is here! Unfortunately we're busy tonight, so pics will have to wait until morning - I haven't set eyes on it yet, it's still in Mrs H's car. Sorry folks

[MrFixr55]

Many moons ago (1963), Dad bought Mom a V-M (Voice of Music) Stereo phono that had a 3 tube "SE" Amp2 50L6s and a 12AX7, 2 detachable speakers, each containing 2 6" speakers.  The VM Changer contained an Astatic ceramic cartridge.The power came from a voltage doubler circuit and the output transformers were larger than normal.  This set sounded rather nice. Unfortunately, when the family house changed hands, the stereo, which had deteriorated and was relegated to the basement, was lost. The large output transformer, large speakers and about 160V on the plates of the 50L6s was the key. A similar formula (About 130V on the plate, 8" speaker and more iron and copper than normal in the OPT) contribute the great sound of your Zenith. I have an RCA 1R81 "Livingston" with power transformer and 245V on a 6V6 output tube and an 8" speaker. This does not sound much better than the Zenith H725 at a reasonable volume. Only at high volume toes the Livingston outperform the H725.

[radiorich]

Hello MrFixr,
We must think alike " I upped the filter cap working V to 160 or 200."I use Nichicon 100ufd at 200 volt capacitor to replace Zenith's normal 80ufd .
Sincerely Richard
P.S. I agree with that Zenith really does sound very nice .