Hi everyone,
It's been a while for me. I thought you folks might be interested in my Sky Rover radio made by Belmont 777 Series C. The cabinet is in pretty decent shape for its age. Unfortunately, I did not take a picture prior to removing the chassis. I replaced all the electrolytics and paper capacitors. I also replaced some of the dog bone resistors, some I left in place because they were well within tolerance, most within 5%. Not sure how they will fair out when they get warm, but so far, the radio is working just fine. It was designed for a long wire antenna, but the 12" or so that is exiting the chassis allows me to get 12-15 AM stations. We do have a 50,000 watt station only 5 miles away so it comes in rather strong. I still have to check the alignment, but the dial seems to be pretty accurate. This radio has the weirdest tuning mechanism I've run across. The original plastic disk was warped, deteriorated and cracked so it was useless. I cut a new disk out of a more rigid plastic and had to taper the rim so it fit into a very narrow 'pulley' (see close up picture). As you can see from the chassis front view, I still need to do some more fiddling to get the dial exactly horizontal.
I did have to replace 3 tubes. Other than that, the electrical restoration was fairly straightforward. As you can see, I'm not trying to restore the chassis exactly like it used to look. The 2 can electrolytics have not been replaced. One of the cans is insulated from the chassis and the rubber insulation was so deteriorated I didn't trust it. So, there is now a hole when the can used to be. I did add a line fuse for some peace of mind. A 3AG 1A slow blow fuse has been adequate.
Now it's on to some cabinet restoration work.
Rich
I will typically leave the filter condenser cans in place for appearance, even if restuffing them is impractical, it's normally easy enough to connect replacements under the chassis. With regard to the dial I have a Musicaire set, made by Sentinel, that uses a similar mechanism to that Belmont, but I think it is still functional, warping and breakage of the disk seems to be a common failure of that design and there are a few articles about how to repair them.
Regards
Arran
Hi Arran,
The tuning mechanism is basically a friction drive. The old disk was so warped, cracked with a missing piece, I could not repair it. I guess when it was new the disk was somewhat flexible and clear. So, I just made a new disk out of a thin but rigid plastic. I had to taper the edge to fit into the drive wheel. This may have been a good thing as it aided the friction drive. I did not realize this was a common failure and there were articles on how to repair them. Wish I knew that before I made the new disk. But it seems to work okay. The mounting plate seems to have enough adjustment to move the dial and still have the disk and drive wheel engaged.
Rich:
Yes it's a friction drive system of course, the RCA/G.E sets with an airplane dial had something similar but they used a semi circle shaped piece of sheet metal, behind the dial assembly, the dial bulbs mounted right behind the scale. I think that a Stewart Warner I have uses something similar, those almost never have problems other then the usual dried out grease on the bearing points. I wish I could remember where I saw the article about the ones with the plastic disk, basically they used some plastic sheet from a craft shop, and a circle cutter, it may have been on the ARF. Here is one by Garry Rabbit https://antiqueradios.com/forums/viewtopic.php?t=71083
Regards
Arran
Arran,
Thanks for the information. That link was very informative. I guess the posting is too old for the pictures to show up, I get a message that the content can't be loaded. But the written information was quite good. It was nice to know that I managed, somehow, to follow much the same procedures to make my disk. I used a compass with 2 points to score the plastic as deep as I could. Then used an xacto knife to score even deeper. Working carefully, I was able to break the plastic. Minor sanding to make it perfectly round. I used a brad point bit to drill the center hole because it has a small tip that will center into the dimple from my compass.
My plastic came from an old LED computer display, I think it is called the diffusion layer. It has tiny dots in it that diffuse the display lights. I figured the dots would diffuse the dial lights.
I was also concerned about the heat from the dial lights, but that doesn't seem to be an issue. I did clean out and lubricate the bearings in the tuning capacitor. I had to remove it anyway because the rubber mountings had disintegrated. I replaced them with rubber grommets. Now the friction drive is smoother with no skipping.
Rich
Rich;
I was not sure whether the pictures would show up or not, sometimes they will not on the browser I am using, but then again the ARF has had a numbers of changes since that was posted, what servers were used, and so on. I should see whether the Musicaire/Sentinel dial is still operational, I think that the issues with the disk have more to do with it being an early plastic that just didn't age well rather then being heat related, I assume it was some type of celluloid. Even a lot of modern plastic doesn't age well, like that used in plastic containers, I've had old containers where they were inside, not exposed to sunlight, not exposed to heat, then I try picking one up and the side will just break out of it, but I have some from the 1980s that are still fine.
Regards
Arran
Well, the Sky Rover is up and running!! The alignment process was pretty straightforward. Though I have to say, all adjustments had to be made from the bottom of the chassis, including the IF transformers which are not slug tuned but capacitor tuned. The IF only required very minor tweaking. The broadcast dial was fairly accurate to begin with, now it's spot on. WWV comes in on 5, 10, and 15Mhz on the dial. Of the 21 AM stations within 20 miles of me, I am able to reliably receive 14. My issue is the static, probably generated by all the 'electronic goop' in my house, does start to become an issue above about 1250 AM. Strong stations will overcome the static with no problems, but weaker stations just can't compete. I thought nighttime might be better reception, but when I investigated the stations, many of them either reduce their output or switch to highly directional antennas. Some stations are as low as 220 watts at night. Of course, the radio is designed for a long wire antenna which I do not have. I've been using a 4' long whip connected to the antenna lead. I'm going to try using my amplified antenna to see if that makes a difference. I have a feeling all it will do is amplify the static, but may allow reception of the weaker stations. It is a fairly small kit from Pacific Antenna that uses a 9v battery for power. One thing I did change were the antenna and ground leads which were just hanging out the back of the radio. I drilled a few holes in the chassis and mounted an antenna terminal strip from a parts chassis. Now the antenna and ground connections are available as screw terminals, much easier to deal with. I also replaced the speaker grill cloth which was in bad shape. I found a pattern that was a reasonable match to the original.
Nice Job!! I have a 1927 Federal F10 that uses a similar system. Very handsome cabinet. Lots of large table radios had wires for antenna and ground instead of terminals. Very common on RCA till the mid 1930s.
Several members have tried using abandoned wire phone lines from house to pole as antennas. My only concern is that these wires run close to the same power lines that carry all of the noise.
Try turning off all LED and CFL lighting, all Digital TVs, Compuuters, network and IoT devices. I other words, your whole house.
A lot of the long time shortwave stations, like BBC, Vatican Radio, etc. have ceased transmitting to North America due to the advent of the internet and streaming.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis
RichG very nice job on that set you can be proud. I’m one of those members here who have used my old landline phone wires as a long wire antenna. Works quite well. I estimate it gives me approximately 60’+ of length and about 20’ high above the ground and I can plug into that antenna in any room. I will say though any of my sets like my 41-250 with built in loop antennas seem to work better with less noise than long wire sets.
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