[MrFixr55]

Hi Red,

A 3 wire plug is a mixed blessing here. When using an external antenna, a ground completes the circuit. However, using the house electrical system as a ground can induce noise carried on the ground conductors. Ground to a cold water pipe or better yet, a "made" ground separate from the electrical system. Ground rods are available from the electrical departments of the big box home stores.

try the external antenna and water pipe first and see how you make out. If improvement is sufficiently significant, then consider the ground rod.

How are you making out on short wave?

Good luck

[RedRobot]

I'll keep the 2-prong then and get a fuse along with the audio jack. I also ordered some speaker wire to try (on separate strands) as antenna and ground wire. Right now I have the chassis out and on the bench again: busy week but once I get a chance I'm going to replace the rubber-clad light wires before I put it back in to test reception with the external wiring. I'll update then, thanks again for all the advice.

[MrFixr55]

The trick is to find inexpensive wire. This does not exist. My "long wire" is #14 THHN. This is the individual conductor used in "Romex" (Type NM) house wiring. Relatively inexpensive. There is also bare wire antenna wire available.

Others have used their former telephone cable from the house to the pole, or if a relatively new 4 conductor wire, the yellow and black wires which are unused if you did not have 2 lines. However, I think that there are "standing waves" even in reception, making the actual length of the wire a variable that should be optimized. The direction of the wire also has a bearing on strength of the signal. the length of the wire varies based on whether you desire reception of the Broadcast Band, shortwave or both.

Several of our members are HAMs. Starting a thread on optimal long wire antenna construction should be helpful.

[RedRobot]

Got some parts, had some adventures.

Prep:
1. Replaced rotting wire for the pilot and dial bulbs, rebuilt the sockets as per the Library page, put in new bulbs: it lights up all pretty again.
2. Cleaned band switcher by applying contact cleaner and switching back and forth several times.
3. Separated out the two wires of a speaker cable, ran one to a water pipe in the basement, and the other out the back door along the hedge to the garage. The goal was just a test, not serious antenna construction.
4. Disconnected the loop antenna, put the ground on screw terminal #3, and tried the antenna wire variously on #2, #4, and pin 3 of the external antenna connector. They were roughly equivalent in the results.

Results:
1. AM reception not exactly better or worse than the loop. I get a few more stations but also more static.  But one big improvement is that the hum peaking at 600 kHz isn't nearly so bad and there's even a weak station in that range. At least it confirms that the interference source is somewhere indoors I think.
2. Shortwave bands still silent. Maybe I need to clean the switch more thoroughly? I'm looking up what it's supposed to look like so I can compare the state of mine.
3. While checking that the ground was connected right my multimeter showed the chassis being at 60V whenever plugged in, off or on. It wasn't doing that before, and I had just been unknowingly touching the chassis to tinker with antenna leads without being shocked or anything. I hadn't changed wiring other than the new lights that are all on the 6V circuit. Could that be something that went screwy with the safety caps?

Also ordered the audio jack, switch, and a fuse holder, they should arrive soon. Went with a  screw type since it's easier to change from outside, though contingent on opening that one knockout hole in the chassis.

[RedRobot]

I tinkered a little more while still waiting for the last of my parts arrived, and I have no idea why the chassis is floating at 60V whether power is off or on.  New safety caps still showing at the rated 0.01uF when measured in circuit, and the hot line is connected to the power switch.  I haven't touched the chassis barehanded since I noticed the problem but I wasn't being shocked tinkering with the antenna mounts just before. When I attach the earth ground wire the chassis grounds normally and hot shows at 120V like before.

I'm still new enough at this to be confused what that might mean, and what approaches to diagnosing/fixing it are wise. Can anyone advise if there's some obvious problem I'm failing to see, or solutions I should not attempt (right now adding a ground and fuse sounds tempting but not if that adds new hazards)

[radiorich]

Hello Redrobot,
Nice it sounds like you put lot progress into the project and I found a good deal on 18 gauge speaker wire one the surplus sites like ebay.

Sincerely Richard

[RedRobot]

Yeah, I found a 100 ft coil of 16 gauge speaker wire for like $10.  I don't know what quality is is for an antenna but I figured that was secondary for just verifying function.

[radiorich]

Nice Find Redrobot,
Well today I replaced some more electrolytics capacitors on 1980s receiver that I am restoring and Wow we hit 60 degrees here .

my long wire is like 75 feet long and It has it's own grounding rod too.

Sincerely Richard

[RedRobot]

Not that warm here yet sadly. And I'm in town but my lot is 120 feet long so there's some space. I don't know how elaborate I want to go with, I'm mostly just seeing what I can get the set to do. My current vision is that I'll use this radio more to play old music and radio shows on an aux in than listening to the  radio, but being able to pick up multiple bands is neat if I get it working.

My next planned capacitor job is on some capacitor plague era PC motherboards. I've been putting it off for ages and kind of dread it because those boards have lots of caps, they're very sensitive to things like the correct ESR, and the caps they were shipped with aren't made any more .

[462ron]

Hi RedRobot, don’t worry about the 60 volts you have on your chassis. If you look at your schematic you see two equal value safety capacitors in series across your power input with the common connection connected to chassis. That common connection is at the center of those caps which puts it at half..60v.. of your input voltage which is usually 120v thus the reason your chassis measures 60v to ground such as a water pipe. Those  capacitors AC resistance, actually impedance at 60Hz is large enough to limit dangerous current from affecting you when touching the chassis but your meter will measure voltage there. You will probably measure that same 60v regardless of which way you plug the radio in.

Ron

[radiorich]

Hello Redrobot,
Yes my Yard is 150 deep by 50 feet wide .
I have Am transmitter plus my General Electric console has a aux from the factory that I use .
when you ground your radio make sure you use a good ground because the ground for your outlets can has lots junk on it and it will cause issues with your radio .
I have one circuit in my house if I have either of these two lights on the hum starts.

Sincerely Richard
P.S. I have couple old mac's that need to be recapped too.

[RedRobot]

Thanks, Ron. I wasn't familiar with phantom voltage until I went researching last night since most of my past electronics work hasn't touched the AC side.That explains a lot, especially since it didn't show on a different multimeter. Even if I still wonder why it wasn't doing that before.

[Arran]

I have also heard of people using welding wire, such as for a MIG welder, for an antenna, I'm not sure how long it will last but it is typically copper plated. The difference is that it is MUCH cheaper then solid copper wire of the same gauge. In the past I had a long length of 14 gauge house wire that I used for an antenna, it was left over from when they replaced the dust collector in one of my shop classes in high school, so I asked about it, I think it was 40 or 50 feet long.
Rich is right about the power line grounds, it does eventually ground to earth, but it's also running parallel to the hot and neutral lines in the walls, which could be radiating RF trash into it through induction. There is a lot of debate about how to create a proper antenna ground, but no where did I hear or read about using the electrical ground for the antenna ground being the best way, though there is no harm in trying.
Regards
Arran

[RedRobot]

Further good news. I went and carefully cleaned and tested the wafer switches (such as I could, there are components packed in tight there). At first I was terrified I broke it since it wasn't getting anything at all then I noticed a new resistor that went loose since my soldering there was sketchy, and fixed it again. Shortwave bands woke up finally. I've got an assortment of stations on the top couple bands even with just the loop. Nothing more than a patch of static on the lowest shortwave band, but I gather that's the quietest one in North America today.

External antenna wasn't actually doing better than the loop today but it's possible it fell out of the hedge or something when I wasn't looking. I can check again when it's lighter and warmer out.

Still got the aux in to add and the fuse once it arrives, but that shouldn't be hard. Found some 3D printable pushbuttons too once I get around to the cosmetics. If not replacements for the chassis pads.

[RedRobot]

I also found the schematic and a construction video for a replica of the original external antenna coupler. Have most of the components, just need to pick up an inductor and a mica cap. And find some prongs that fit the connector. Maybe that will make it work better with an outside wire.

I was even picking up some Japanese station in the 6-7 MHz range along with some others on that lowest SW band. Which is maybe NHK World related from France at 6105 kHz looking it up but it was closer to 6500 on the dial so I'm guessing I still need to figure out some adjustments.