View Full Version : Finally snagged a Zenith tube radio


Snade
03-14-2008, 01:03 PM
Living in the Chicago area, I hold up Zenith as a great, local company - in particular the radios and TVs it made in the 50's and 60's.

I've been scrounging for a Zenith tube radio or console for a couple of years.

Today, the local thrift had one of these priced at $6.95. I grabbed it.

Zenith Model G730W AM/FM radio. Very nice shape, a few scratches, but in amazing shape.

7 tubes, circa mid-1950's.

It works, :banana: listening the AM right now in my basement and reception is better than my Tivoli Model One.
http://www.gallagher.com/photos/2008/zenith_radio.jpg

http://www.gallagher.com/photos/2008/zenith_radio_2.jpg


Ok Snade, calm down.

Cheers.

Sandy G
03-14-2008, 01:12 PM
I've got its double-1st cousin, mine's a blonde cabinet that is squared off rather than "arched", but I'd about guarantee the works are the same. Good price, too !

Ultra-Hog
03-14-2008, 01:15 PM
That's sweet! Aren't those tube radios great? I love the way they sound. Nice and warm with great reception to boot. If you decide to do any preventative maintenance, like replacing the filter cap, there are lots of excellent sources available.

Enjoy! :thmbsp:

onepixel
03-14-2008, 01:19 PM
Sweet, sure is pretty!

Snade
03-14-2008, 01:36 PM
The sticker on the bottom of the radio.

http://www.gallagher.com/photos/2008/zenith_radio_3.jpg

fsjonsey
03-14-2008, 06:14 PM
That, In my opinion, is one of the best looking zenith sets of the 50's. Almost reminds me of a european radio.

Robie
03-14-2008, 08:32 PM
Very cool, my man. Bet it sounds great in your man cave.

skippy_ps
03-15-2008, 10:02 AM
I like it - cool cabinet.

Murray

barrynsue
03-15-2008, 10:16 AM
Tube radios are great! Besides the quality of sound, the reception capabilities always amaze me. Brings back great memories of our youth also. Every time I find a new radio, I just think about the news that was broadcast to the families sitting around listening, the the comedy shows, and just a different era.

Nice find on the Zenith.

Barry

Nolan Woodbury
03-16-2008, 09:04 PM
That'll bring pure radio enjoyment, and is as pretty as anything Zenith ever made, IMHO. Looks like it has a good home too!

What's left of the old Zenith factory? Anyone in the area ever travel over there for a look?

mhardy6647
03-17-2008, 09:35 AM
Note that it's a series string (AC-DC) set and almost certainly not isolated from the AC mains by a power transformer.

gearhead
03-17-2008, 10:33 AM
Note that it's a series string (AC-DC) set and almost certainly not isolated from the AC mains by a power transformer.

Please translate!
I have several tube radios, & I'm about 1/2 scared of plugging them in.
I'd like to update them so I can use them.
Nice looking radio, Snade! Got any nudie shots, or are you keeping those under your mattress?

DENNYDOG
03-17-2008, 10:42 AM
Beautiful radio Snade!

I like my ss Pioneer gear but now that I've gotten the tube bug it is fun learning the history of audio equipment that was made here in the US like Zenith, Emerson, Fisher and many that I didn't mention.

Gearhead, who is that in your avatar? She musta been around during the tube era.

mhardy6647
03-17-2008, 12:28 PM
Please translate!
I have several tube radios, & I'm about 1/2 scared of plugging them in.
I'd like to update them so I can use them.
Nice looking radio, Snade! Got any nudie shots, or are you keeping those under your mattress?

No power transformer; all voltages are taken directly from the AC line. Since there's no transformer in the power supply, such equipment could, in theory, be operated from a DC power source. Thus the "AC-DC" moniker.

The filaments of all the tubes are in series and add up to 120 V (more or less). Note the 35 and 19 V filament tubes in the schematic. The 7 tubes' filament voltages sum to 108V (if I am reading the top left tube as a 6V).

I have one of these radios at home, too. It's possible that there's an isolating 1:1 transformer in this set between you and the electric grid, but I don't think so...

Sandy G
03-17-2008, 12:36 PM
In other words, watch out, it CAN bite !

Snade
03-17-2008, 12:54 PM
In other words, watch out, it CAN bite !

Now I'm scared to open it. :D

Fisherdude gave me the name of a local tech and I plan to bring it over in the next week or so for recap and a once over per suggestions from Sandy and others.

The AM reception is simply amazing. Much better than any other portable radio I own and when you tune in a station, you have a lot finer gradations of tuning in the strongest signal.

I plan to use it as a daily runner for morning talk radio - produces the human voice with a nice warm tone.

WhiteSE
03-17-2008, 01:00 PM
That is a cool looking radio!!!

mhardy6647
03-17-2008, 01:38 PM
oh, you can open it... don't do it with it plugged in unless you're comfortable working with HV. That admonition would apply whether or not it's got an isolating transfomer in the P/S!

You can (and might well want to) buy an isolation transformer for bench use, testing, or routine use of a "killer" chassis radio or TV. You'll note that the knobs are plastic on the radio...

Aage
03-17-2008, 03:26 PM
Yeah, so when you test it, standing on a concrete floor in your wet bathing suit while picking up the chassis with your bare hands is Definitely Not Recommended! :smoke:

Jeffhs
03-20-2008, 04:35 PM
It's possible that there's an isolating 1:1 transformer in this set between you and the electric grid, but I don't think so...

My Zenith MJ-1035 has eleven tubes in two series strings, wired in parallel, with a filament transformer (if a tube burns out in one string it will darken half the tubes in the set, leaving the other string working as normal), so some of these radios were in fact designed with series-parallel filament strings. The 730's filaments may be wired series-parallel and powered through a transformer as well; this type of wiring would make sense in any radio with more than eight tubes, as the combined filament voltage of, say, an eleven-tube set would total well over 117 volts if there are two or more 50-volt tubes in the string. The filament circuit of the MJ-1035, for example, puts the radio's two 50EH5 audio output tubes on two separate strings.

As to a 1:1 transformer offering any kind of isolation from the power line, I agree with you; I don't think so. If one side of the power line is connected directly to the chassis, as in all AC/DC radios, the latter is definitely not isolated from the line, even by the transformer, unless the AC plug is inserted in the wall outlet such that the chassis is grounded. The problem with that is that there is a 50-50 chance of plugging the cord in so that the chassis is hot, rather than grounded; it is almost impossible to know for sure, as I am about to explain. The only way to know for certain is to use a common light bulb, with one side of the socket connected to the center screw of the outlet plate which is grounded. The other terminal is temporarily connected to each side of the wall socket in turn (by inserting the lead--carefully, of course--into either slot of the socket); the connection which causes the lamp to light to normal brightness indicates the hot side of the circuit. This test is almost infallible, unless the outlet was wired incorrectly. Today's strict and by-the-book electrical codes won't allow such a mistake to go unnoticed or uncorrected, but homes built in the '70s and earlier sometimes had cross-wired outlets; often, the problem was never corrected or even noticed until the wall socket had to be replaced, or other work was done on that circuit. As long as the outlets worked, they were left alone.

anden
04-19-2008, 06:51 PM
These 7 & 8 tube Zeniths are indeed great.....starting in about 1955 they included electrostatic tweeters on either side of a 8 inch main speaker providing fantastic audio. Zenith changed to a 5 x 7 inch oval speaker with one electrostatic in about 1958......still sounded great.

Many folks think they date to the early fifties due to the last patent date being 1951, but they're later...the y832 & B835's are 1955-56 and the G730 is 1958. Then the popular K731 is about 1963.

Zenith really ended the era of tube radios with a bang ! I bought three today at a radio show - a H845 for $10, a K725 for $20 and a neat tube portable for $ 8. All work ! It was a good day.

Jeffhs
04-20-2008, 12:51 AM
These 7 & 8 tube Zeniths are indeed great.....starting in about 1955 they included electrostatic tweeters on either side of a 8 inch main speaker providing fantastic audio. Zenith changed to a 5 x 7 inch oval speaker with one electrostatic in about 1958......still sounded great.

Many folks think they date to the early fifties due to the last patent date being 1951, but they're later...the y832 & B835's are 1955-56 and the G730 is 1958. Then the popular K731 is about 1963.

Zenith really ended the era of tube radios with a bang ! I bought three today at a radio show - a H845 for $10, a K725 for $20 and a neat tube portable for $ 8. All work ! It was a good day.

You are so right as to the popularity of the K731 in particular, as I see those sets on ebay all the time. Zenith must have made millions of those sets in their heyday. (By contrast, the MJ1035 doesn't show up on the bay nearly as often; I've seen only one such set there in the last couple weeks or so.) I have a K731 that still works, looks and sounds great after 45 years (all it needs now is a new power cord), a C845, and an MJ1035 that both still work as well as can be expected of radios of that vintage (the MJ1035 has a bit of power-supply hum, but I knew about that before I got the radio about two or three months ago). The MJ1035 and C845 in particular are excellent when it comes to RF sensitivity; I live between two cities and can hear both areas' major FMs on these radios just fine, in addition to two stations some 60 miles south of here, using only a 6-foot length of wire on the FM antenna terminal.

The K725 is basically a K731 in a plastic cabinet. I have a schematic for the K725 that is apparently close enough to the '731 that Zenith (and apparently Howard W. Sams) didn't bother to publish separate service info for both receivers.

I'll have to look inside my C845 and MJ1035 again to see if I can find the second tweeter; the last time I had the back off either set I only saw one high-frequency transducer.

Zenith did not use the plastic-cased electrostatic tweeter in the C845 or the MJ1035; in its place in at least these receivers are two standard 5" speakers on either side of the 8-inch main driver, which is fitting for these sets since they weren't cheap when they were new (the C845 probably sold for over $100 when new in the late fifties, while the MJ1035 sold for close to $200 when it was new in the early 1960s). The K731 may have been meant as a lower-end table radio, with an audio system to match (one 35C5 output tube, with a section of, I believe, a 19T8 being used as the preamp--the electrostat tweeter is driven directly from the plate of the 35C5); this is not to say the 731 sounds bad--on the contrary, it sounds very good for a small table receiver, considering it has the 3" plastic electrostatic tweeter. One thing these Zenith radios had that many other table sets of the same vintage did not have was a true tone control, i.e. a control that adjusted the entire frequency response curve of the audio stage rather than simply cutting the highs.

anden
04-20-2008, 08:33 AM
Jeff, thanks for the info - I've recently been on a 1950's -60's Zenith jag. Another interesting aspect to the these Zeniths is their point to point hand wired chassis. Many other makers had adapted the printed ciruit boards which were trouble prone. I also have a K731 (legged version). Do you know what the cost of a K731 was back in 1963? I do know that the H845 went for $129. which was a good chuck ofd money back then.

Some kind of flash-back has inspired my recent interest.....Back in 1973 when I was 12, I inherited my grandmothers H845. I remember my friends being very impressed at the sound it produced...after all most of us kids only had little Radio Shack radios and had not experienced the World of Zenith yet. Only a big German set can out perform them, but these ran up to $300.

It's nice that prices are generally low - but they are one the rise.

Jeffhs
04-20-2008, 09:13 PM
Jeff, thanks for the info - I've recently been on a 1950's -60's Zenith jag. Another interesting aspect to the these Zeniths is their point to point hand wired chassis. Many other makers had adapted the printed ciruit boards which were trouble prone. I also have a K731 (legged version). Do you know what the cost of a K731 was back in 1963? I do know that the H845 went for $129. which was a good chuck ofd money back then.

Some kind of flash-back has inspired my recent interest.....Back in 1973 when I was 12, I inherited my grandmothers H845. I remember my friends being very impressed at the sound it produced...after all most of us kids only had little Radio Shack radios and had not experienced the World of Zenith yet. Only a big German set can out perform them, but these ran up to $300.

It's nice that prices are generally low - but they are one the rise.

I'm not really sure what the K731 sold for when it was new, but judging from the fact that Zenith made so many of them between about 1958 and 1965, they couldn't have been that expensive.

I am not the least bit surprised that the C/H-845 series sold for $129 when new in the late 1950s through about 1961; after all, these radios were built with quality in mind, as were all Zenith radios (and TV sets) of that era. (The MJ-1035, a hi-fi stereo receiver by Zenith with a stereo phono input, sold for close to $200 when it was new, but it, as well as the '845 series and most of Zenith's other hi-fi radios from the '50s and early sixties, can be had for very low prices these days on ebay.) The '845 series had a true tone control, a two-way speaker system and enough audio output to blow a person clear out of the room if run wide open, not to mention signal-grabbing power that most of today's radios cannot match. The '845 series had a 6BJ6 RF amplifier tube that worked for both AM and FM, as well as two IF stages for both bands, so I'm sure these sets sold well in far-suburban and even fringe reception areas as well as near-suburban and urban reception environments. I now live in an area where the AM and FM signals are not exactly weak, but not as strong as they were when I lived in a Cleveland suburb. No matter. My C845 (and also my MJ1035) pull in every major Cleveland FM station using just a 6' length of wire on the FM antenna terminal; when the band opens up in the summer, the FM dial just lights up with stations from one end to the other, again using only indoor antennas.

You are correct in your observation that the prices of these older radios are rising, even on the used market. The MJ-1035 can still be had (for now, anyway) for the proverbial song on ebay and other auction sites (sometimes, however, without the extension stereo speaker), but I read on an antique radio website recently that this was only due to the fact that the MJ1035 is a relatively unknown ("sleeper" is the term used on the site) receiver, in spite of its high-fidelity sound, above-average sensitivity on AM and FM (the latter owing to an RF stage [half a 17JK8 on FM and a 12BA6 on AM] and two IF stages on both bands), and so on. Anyone would be hard-pressed these days to find a table radio with equal or better sound than any of the better Zeniths from the '50s-'60s, except for the large German sets (Grundig, Emud, Korting, et al)--but again, as you said, those German radios cost an arm and a leg, even used. I read somewhere recently (I think it was here in AK, perhaps in this very forum) that the German sets had excellent fidelity, albeit perhaps with exaggerated bass, and they weren't exactly station grabbers by U.S. standards, but they were built with quality not seen in American electronics today. I was given a Grundig model 2168 by an old friend about 30+ years ago; the radio was in bad shape at first, but when I got it back together again (with only one speaker; from the looks of the cabinet, however, the set probably originally had three, two at either end of the cabinet with the main driver at the front, above the tuning dial, and may have been set up for stereo FM to boot, though I could not see any kind of stereo indicator on the front panel) it worked fairly well. I connected an old Webcor reel-to-reel tape deck to it and had a nice little mono audio system the six or seven years the radio lasted. It gasped its last breath in the very early '80s when the FM tuner quit, but no matter--by that time I had bought a new solid state Zenith integrated stereo system.

Darn!...I should have held on to that Grundig; who knows, it might have been worth something today. I don't know how much the model 2168 would fetch on ebay, for example (especially in the sorry shape mine was in; no dial glass, the EM84 tuning-eye tube flopping around loose at the left end of what should have been the tuning dial, the missing stereo speakers . . .) but one never knows. I could have listed it as a parts set and gotten a few dollars for it--that is, if I had known about the Internet and ebay then (was ebay even in existence in the early 1980s?).

anden
04-21-2008, 05:58 AM
Now you've done it Jeff...I want a MJ 1035, they seem to indeed be very impessive. Must have been among the highest tube count in a table radio of the era.

I've had a few German sets and the of course are nice, but there's something about the musical quality of the sound comming out of the 800 series Zeniths - they just got it right !

Bruce221
04-26-2008, 05:52 AM
YES-oh yes I too love the zen --have 2 toumbstone ones 1938-and a 1933-and I just love the warm sound ect -and the wood got to have that wood.