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  #46  
Old 04-02-2006, 06:56 PM
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Nolan Woodbury Nolan Woodbury is offline
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Aaarg...don't think the link is opening, so we'll try this:

Top location:



Underneath:

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  #47  
Old 04-02-2006, 07:39 PM
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Nolan Woodbury Nolan Woodbury is offline
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A really great radio

Here are two styles of the K731. I like both (what's not to like?) but the "Colonial" style with the shorter legs to me, looks a bit more classy. I'm not much into the "TV console" look, which is what Zenith was after I think.



Other variants of this radio, the T2542 and the T350 are nice sets too. In fact, I have a T350 playing on my desk now, and it's unusual with a brushed metal faceplate that stretches over the dial and the control knobs- neat.

Last edited by Nolan Woodbury; 04-05-2006 at 12:43 AM.
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  #48  
Old 04-02-2006, 08:35 PM
OldWolf
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Nolan -
Very nice pictures. It looks like I got my wire into the correct position.

Sigh... ...now I need to figure out what to do next.

Do any of the tube sellers provide the service of testing your tubes prior to purchase?
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  #49  
Old 04-03-2006, 01:22 AM
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wa2ise wa2ise is offline
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Quote:
Originally Posted by OldWolf
I can make out AM radio stations, but they are very faint and I have to crank the volume up to 100%. There is a lot of static, and if I tap the radio I get more static each time.

Check for poor contacts on tube sockets and tube pins, and dirty band switches. Touch the top glass seals of each tube one at a time and wiggle the tube a little. If you can get a burst of static with a particular tube, likely there is a loose contact. Remove the tube (disconnect the power cord too!) and with pliars very gently squeeze the tube socket pin grippers. You just want to tighten a little the tension of the tube socket pin gripper. Practice on a junk socket first.
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  #50  
Old 04-03-2006, 11:29 AM
OldWolf
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wa2ise - That is a good idea, tightening the socket pins. My problem started when I removed all the tubes to clean them. When I reinstalled, no AM when I had AM before the cleaning. Maybe this will be an easy fix for the FM too.

Has anyone else noticed all the the flux spattered EVERYWHERE on the inside of the chassis. I thought maybe it was just my radio but then I noticed it on some of the above photos of Nolan's.

I work on the radio tonight and report back.

This forum Rocks!
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  #51  
Old 04-03-2006, 03:53 PM
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wa2ise wa2ise is offline
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Thanks, but be careful that you don't crush the pin grippers. Maybe a better tool to use is a dental pick that you can leverage the point between the phenolic wafer and the outside of a pin gripper. You just want to tighten it by about 1/64th inch.
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  #52  
Old 04-03-2006, 09:47 PM
OldWolf
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Music To My Ears!

Tightening the pin grips made all the difference in the world. First I removed each tube and lightly polished the pins. Next I gently tightened the pin grips. After reinserting the tubes I could hear AM! Still, the radio buzzed too much. Next I snugged up each gripper while the tube pin was inserted. I did this for all the tube pins.

When I turned the radio on, the AM reception was crystal clear! To test the FM I had to reassemble the radio so that I could connect the FM antenna.

With the radio assembled and the FM antenna couple attached to the power cord, I am happy to announce that I now can recieve FM.

No static, no buzzing, just rich and clear music from the two speakers.

For the next 3 hours I listened to a live performance of the North Carolina Symphony on WCPE 87.9 out of Wake Forest, NC. (If you like classical music, Google WCPE and you can listen to this station online).

Thanks for all the tips and pointers everyone. And thanks to wa2ise for the tip that finally got my radio running 100%.
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  #53  
Old 04-04-2006, 03:18 PM
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Nolan Woodbury Nolan Woodbury is offline
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Glad to hear it's among the living Brad. With just a bit of care and concern, the Zeniths of this era can return an amazing amount of service.

Never had an issue with socket tightness, but I've sure found most of them to be dirty...I'll clean the tube pins with a bit of Scotchbrite (red pad) douse the sockets with a blast of electronic cleaner, then (carefully) dry with compressed air. After, I smear just a dab of dielectric (sp?) grease on the pins and shove em' back in. This may have the same effect as tightening, and after considering that for a moment (wiggling the tube back and forth to free it) that might be a great place to first check if the radio isn't working, but isn't humming either.

Enjoy your K731 Brad! Seems you've earned this one-
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  #54  
Old 04-04-2006, 09:01 PM
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Blooze Blooze is offline
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Good deal, Brad!! Glad to hear you got her working.

Mine seems to play all right on AM and FM, just some background hum. I still have yet to take the chassis out as I've been too busy with other things. Need to do that so I can replace the caps and see if some new filtering will take care of that hum.

Shane
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  #55  
Old 04-05-2006, 08:32 AM
OldWolf
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I've noticed mine drifts out of frequency for about 15 minutes, until the electronics are fully warmed up. The AFC works sorta, but it still drifts, when AFC is on and the system is warming up. Drifting can (is) be typical I understand, but is it a warning of a component failure?

I'm spoiled by the PLL tuning of my digital radios!
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  #56  
Old 04-05-2006, 10:12 AM
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Nolan Woodbury Nolan Woodbury is offline
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If I'm not mistaken, a bit of drifting is common until all the tubes are up to full operating temperature. When I'm getting a set ready to listen to, I'll turn it on with the volume down for five minutes or so, then turn everything up and find my station.

I also think that drifting reception can be a sign of capacitor failure...Chad, is this where you recommend the use of freeze spray to isolate the problem?
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  #57  
Old 01-21-2007, 06:32 PM
subwoofer149
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I have a Zenith K731 tabletop radio with the green antenna wire to the chassis that is unhooked. I cannot seem to open the photo files in this article to see where this should be connected.
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  #58  
Old 01-22-2007, 04:32 PM
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Quote:
Originally Posted by Tom Bavis
The 12DT8 is the only tube used for FM, and not AM. So try it first.

The dot before 100 is for Zenith's own FM station in Chicago. A handy dial calibration point at the factory?
That little white dot can also be used as an alignment aid if you ever have to realign the set. The symbol marks 99.5 MHz and was, as mentioned, the frequency of Zenith's owned and operated (O&O) FM in Chicago in the '50s through about the mid-'70s. The station was known as WEFM in those days; it is now WUSN, "US99" C&W (country/western). Most of Zenith's radios from the '50s until the end of the '70s had the dot at 99.5, but by 1976 or so this was just a carryover from an earlier time (the WEFM era) and was kept on the radios only for nostalgic value. Both my Zenith K731 and C-845 have the 99.5 marker on their slide-rule tuning dials, but the '845 has two parallel horizontal lines, rather than a dot, at this point. My C845 also has the two parallel horizontal lines on the AM tuning dial at 640 and 1240 kHz (the old Conelrad emergency warning frequencies) in addition to the Conelrad symbols themselves. One version of the K731, probably a slightly older version than mine, has the CD symbols on the AM tuning scale (my set does not have these icons, so perhaps it is one of the newer models made after 1963, the year Conelrad was abolished in the U.S. in favor of the Emergency Broadcast System).
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  #59  
Old 01-22-2007, 06:41 PM
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Nolan Woodbury Nolan Woodbury is offline
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Quote:
Originally Posted by subwoofer149
I have a Zenith K731 tabletop radio with the green antenna wire to the chassis that is unhooked. I cannot seem to open the photo files in this article to see where this should be connected.
The wire goes to the "F" terminal. The other screw ("G") is for ground.
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  #60  
Old 09-10-2007, 01:12 AM
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Jeffhs Jeffhs is offline
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Quote:
Originally Posted by Sandy G View Post
If that's the translucent plastic "T" antenna, Yeah, that oughta work fine. I try to mount mine close to a window & hide 'em kinda behind the drapes. If you are out in the country, don't expect this little guy to do too well on FM- but if you are in, or close to, a town, you should be OK.
I live some 35 miles east of Cleveland, with the transmitters for all local AM, FM and TV stations some ten miles further west of downtown (the signals must travel at least 40 miles to get to my small town; reception on car radios is somewhat iffy on certain stations because of that). My own K731 gets every station in town just fine, using only the line cord antenna in my first-floor apartment. The radio's FM dial just lights up with stations in the summer, when the FM band opens up. I get stations from southwestern Ontario, Canada, Detroit, Michigan, and Toledo, Ohio (northwestern part of the state) all summer long and into the fall.

The K-731 has switchable AFC, so you should be able to get stations very close to each other on the dial. For example, the classical music station serving Cleveland moved from 95.5 to 104.9 three years or so ago. 104-9 is right next to a strong country-western station on 104.7, about 35 miles further east of me (I am between two towns, Cleveland to the west and a burg called Ashtabula, almost right on Lake Erie, to the east, so I get stations from both areas very well). My radios with fixed AFC don't get 104.9 worth a darn, but the K-731 (and also my C-845) get the station just fine with the AFC off.

The K-731 is a great-sounding radio, one of Zenith's more popular models for the late '50s-early sixties. The '731 shows up all the time on ebay and can be had almost for a song, figuratively speaking. My '731 is in the walnut cabinet that looks like a small TV console, has a 5x7 oval speaker and a 3" electrostatic tweeter, and again, it sounds great. The only other Zenith radio I have that beats it for sound quality is my C-845.

The K-731 came in at least two cabinet styles, and was available in walnut and blonde finishes. The K-731 used chassis 7K07 or 7M07 and had seven tubes (the first digit of the model number of most Zeniths through the '60s usually was the tube count; e.g. the K-731 has seven tubes, the C-845 has eight tubes, the mighty MJ-1035 has ten tubes, and so on). The first digit of the chassis number will be the tube count as well; for example, chassis 7K07 has seven tubes, chassis 8C01 has eight tubes, etc. This convention continued with Zenith's transistor sets. The Zenith Royal 500 from the early-mid-1950s has eight transistors (I think, if I remember correctly); the chassis number, accordingly, began with 8ZT, the eight being the number of transistors.

I apologize for rambling on like this, but I am a Zenith radio collector and cannot stop talking about them. Zenith is my favorite brand of radio and entertainment gear, at least it was until the company stopped making radios in the early 1980s. It still is, however, as far as their older sets are concerned. For sound/build quality and reliability, Zenith radios and TVs can't be beat, again speaking about their older sets. The world lost a darn good brand of radios and TVs when Zenith disappeared in the nineties, to be replaced by (gasp!) Gold Star.
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