New member, just got my first old radio

Hey everyone,

I just found your forum last night and found myself really enjoying the passion that you all obviously feel for your radios. I am the same way myself, although so far it has mainly been with defunct video technology like Betamax and the RCA Videodisc system, as well as the precursor to laserdisc, Discovision! Anyway, several months ago I found Coast To Coast AM on the dial and that was it, I've been hooked on radio ever since. And slowly, but surely I've been buying radios since then. Admittedly, the radios have been modern so far, but it's helped me to build my interest in the hobby. My GE Superadio III really cemented my relationship with radios, and I love that radio to death (I hope that's not sacreligious here since it is not an antique tube radio, but it's still a really great machine). Anyway, long story short. I recently purchased my first antique tube radio (although I've owned one prior that was a gift - more about that cool old radio later), a Zenith K731. I have some questions and could really use some advice about the radio based on what I have read so far, and what I might like to do with the radio. It seems you are all really knowledgable about this stuff and could offer me some good advice.

First, let me tell you about the radio itself and it's current condition. I got it on E-Bay for about $40 including shipping. Based on what I have read so far, I know this much about it.

The radio has the Early Americana cabinet and the cabinet is in near perfect condition. The grill is perfect and the dial pointer is nearly straight up and down. Cosmetically the only flaw I can see is that behind the knobs on the stems themselves there appears to be a little bit of gunk that I am hoping can be cleaned.


When the radio arrived yesterday at work, I plugged it in (my co-workers love to come by my desk when my latest piece of technology arrives to see what ancient equipment might be making it's way to my house now) and after about fifteen seconds the radio came to life. I keep a small radio on my desk and we were blown away by the sound of this Zenith. The voices were booming out of the unit and I've never heard a radio with sound like that. It sounds better than my Superadio and that truly surprised me. I was also impressed that the reception was better than the radio on my desk and new I had found a new partner for my late night journeys across the AM band. You will probably appreciate that a few co-workers were quite envious of this radio and I've got a feeling that a few of them might be looking for something similar soon (it helps that I've been spreading the Coast To Coast bug). The only sound problem I noticed was when I adjusted the volume. It got a little scratchy until I found the volume I wanted. Reception is good acorss both bands and the dial appears to be well calibrated. As I type this out I am listening to a great old Jazz station from Newark, NJ at 88.3 FM, WBGO. The radio sounds simply beautiful. Certainly better than when my co-worker switched it yesterday to Hot 97, it just struck me as wrong somehow to hear the radio playing hip-hop, kinda surreal. LoL.

The radio has the CD markings on the dial, so I guess that means it is pre-1963, and I know that it has the 7K07 chassis.

My questions about the radio in general are this;

1. What are the differences between the 7K07 chassis and the one I hear most people mention, the 7M07 chassis?

2.. It seems, based upon the number of threads for this particular model that it must have been quite popular. Is it considered to be a good radio?

3. I haven't had a real opportunity to compare it with the Superadio yet, but I was wondering how it might be expected to perform as far as AM reception. I know the GE is considered one of the best ever, but I have read that these old radios could really pull them in as well. Thoughts?

and finally, when it comes to advice, I wonder this:

Should I attempt to change the tubes if the radio is working? Would a new set of tubes potentially improve performance? I priced a full set of tubes for the radio at $40 from vacuumtubes.net, is that a good price?

How can I correct the scratchiness when adjusting the volume? Are repairs on these radios something that a layman can do? I've never soldered anything before, but I am always game to work on electronics and not intimidated at all.

Should I be concerned about wheter or not this radio has a Selenium thingee, and is it OK to leave it plugged in and turned off when I go to work?

Or perhaps I should just sit back and enjoy the radio and leave well enough alone?

Oh, and one last question: I have read on another thread that some models of this radio had a lighted pointer, and some had a lighted dial. Mine does not appear to have either option functioning, this I definitely would like to fix. Any suggestions on how to accomplish this would be greatly appreciated.

Thanks in advance for any advice you can give me, tonight I will open the radio up and take a look inside and report on what I see.

Attached is an actual picture of the radio I purchased, not the best pic, and I don't think it does the radio justice, but I am happy to post a pic of my new friend

Thanks,

Scott

PS - The other old radio I once owned was a Hallicrafters S-38. I was attempting to restore it (wasn't doing the best job I imagine as I had not done enough research) and finally, the boyfriend decided that the radio had to go. Well, this time, the boyfriend is going and the radio is staying