• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Old Emerson Tube Radio... great find!

First of all let me say that I think there should be a forum devoted to radio.

Now though, check out this AM radio that I got a thrift store for $15 US- Click Here! I am sorry; this photo was taken before I cleaned it up(it came clean with a damp rag).

Check out the inside BEFORE and AFTER I cleaned it!

The tubes are 100% original.

But... I was wondering about constructing a new antenna for it; the original is just a coil glued to the backboard; which actually works surprisingly well. I do not see a ferrite rod.

I have access to free magnet wire at work and was considering getting a bunch of it and wrapping it around a cardboard poster tube.

AM radio is odd, though, so I don't want to do anything that will adversely affect my reception. Any suggestions?

Thanks,

Trevor
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
Well, 40 years ago, that plastic Emerson was one notch above "junk".

Junk has got a lot junkier since then: this may be very fine by today's standards.

> I was wondering about constructing a new antenna for it; the original is just a coil glued to the backboard; which actually works surprisingly well. I do not see a ferrite rod.

Of course it works well. Why wouldn't it? Ferrite makes sense with a more sophisticated RF amp than a 5-tube radio has. And ferrite became common when sand-state radios got too small for the air-core loop antenna. And AM radio reception is limited by atmospheric static: even a very "crummy" antenna will bring signal+static above the tube noise level. If you have the space (you do), the air-loop is an excellent wave-catcher. You can't beat it, and are unlikely to equal it with home-wound.

How does it sound?

If you work inside it, remember it is HOT CHASSIS!!! It will electrocute you any time it is plugged in, even when "off".
 

dhaen

diyAudio Moderator Emeritus
2002-06-10 12:01 pm
U.K.
www.keystrobe.co.uk
That "frame aerial" (as we called them in the UK) performs well because it is resonant. It forms part of a tuned circuit which resonates at the frequency you are tuned to. Ferrite rod aerials/antennae work in the same way. You'd need a big non-resonant aerial to better that performance.

As a boy I had one about 10 foot square in my bedroom to receive far-away stations.

Both these types are directional. This can be used to "reject" interference from unwanted stations.
 
Re: Re: Old Emerson Tube Radio... great find!

planet10 said:
I've never seen one that filled with dust... 50C5 output tube?

Don't know much about antennas, i do know there are a few places to go look out on the net.

dave

Yes it was quite dirty; I have a feeling it was stored in a garage for years and years.

Actually, it's a 50B5.

Yeah, I've known about the C. Crane company for a while now; they have some GREAT stuff!


PRR said:
Well, 40 years ago, that plastic Emerson was one notch above "junk".

Junk has got a lot junkier since then: this may be very fine by today's standards.

> I was wondering about constructing a new antenna for it; the original is just a coil glued to the backboard; which actually works surprisingly well. I do not see a ferrite rod.

Of course it works well. Why wouldn't it? Ferrite makes sense with a more sophisticated RF amp than a 5-tube radio has. And ferrite became common when sand-state radios got too small for the air-core loop antenna. And AM radio reception is limited by atmospheric static: even a very "crummy" antenna will bring signal+static above the tube noise level. If you have the space (you do), the air-loop is an excellent wave-catcher. You can't beat it, and are unlikely to equal it with home-wound.

How does it sound?

If you work inside it, remember it is HOT CHASSIS!!! It will electrocute you any time it is plugged in, even when "off".
Thanks for the warning! I'll remeber to unplug it.

It sounds EXCELLENT... far superior to any AM/FM tuner I've ever owned.

I will be getting an air loop antenna from the C. Crane company when I have the money; hopefully I'll be able to pick up stations from San Fransico and Los Angeles(at night, at least), as I live about halfway in between the both of them

wa2ise said:
That antenna (coil of wire on a piece of cardboard) is the original factory antenna. That's what they looked like back then. No need to replace it.

Be sure to replace all wax capacitors.

I know it's original! I want to pick up more stations!

What kind of caps should I replace them with? Electrolytric?


alejo said:
good job, good clean but you erase the labels in tubes, write for security.
think in the future when you must exchange this tubes.

Alejo

The original sticker with the list of factory patents, and chart of tube locations is still there, so I knew it was safe for me to clean them. It would be cool if the original silk-screening was still there, though...


dhaen said:
That "frame aerial" (as we called them in the UK) performs well because it is resonant. It forms part of a tuned circuit which resonates at the frequency you are tuned to. Ferrite rod aerials/antennae work in the same way. You'd need a big non-resonant aerial to better that performance.

As a boy I had one about 10 foot square in my bedroom to receive far-away stations.

Both these types are directional. This can be used to "reject" interference from unwanted stations.

Could one build one of these out of copper tubing? I could build a huge one, and mount it on my roof; I could also make a turntable for it to be on, that I could control form my room to rotate it for better reception... good idea? ...:whazzat:

I looked on the bottom and found the sticker with the Model No-, it's an Emerson Model 653.

Thanks for all the replies!

-Trevor
 
Re: Re: Re: Old Emerson Tube Radio... great find!

Sir Trefor said:
Be sure to replace all wax capacitors.

What kind of caps should I replace them with? Electrolytric?

-Trevor

No! :bigeyes: Electrolytics are very leaky and will be way worse than than even the old wax paper ones. Ordinary polyester caps will be just fine. Use FKP1 types (foil and polypropylene) if you really want to go nuts. :cool:
 
No! :bigeyes: Electrolytics are very leaky and will be way worse than than even the old wax paper ones. Ordinary polyester caps will be just fine. Use FKP1 types (foil and polypropylene) if you really want to go nuts. :cool:
I have a 1959 McIntosh FM/AM tuner unsed for decades that works OK. Can I assume that I should replace the capacitors to increase performance?

YOu comments appreciated.
 
WARNING. connecting anything to the electronics inside this or any old radio that does not have a power transformer can be dangerous. These old radios had a direct connection from one of the terminals on the power line plug to the internal circuitry. Connecting an external antenna to the internals of this radio is electrically the same as plugging that antenna into the wall outlet. Anyone touching the antenna could be fried! If you want to experiment in this manner get an isolation transformer and wire it between the radio and the wall outlet.

The 50B5 and the 50C5 are similar tubes. The pinout on the 50C5 was changed to meet the then new UL creepage requirements.

My wife and I were doing some cleaning and she got one of my old Zenith Transoceanics down off the shelf. It was pretty dusty and I can't remember the last time it was used. I plugged it in and was sucking in stations from Europe within about a minute.
 
You can couple a long wire antenna to the existing loop antenna. One can do that by having a loop or two of wire about the size of the set's loop antenna adjacent to the set's loop antenna (place it on the outside of the back). One end of this new loop connects to a ground, and the other end connects to a long length of wire. Don't directly connect any wires to the set. Just be sure that strong local stations do not sound distorted. Strong stations overloading the radio can cause intermodulation distortion products, which can trash up reception of the weak signals you are looking for. It won't break anything in the radio, so not to worry about that.