Old radios, restored and back on air.

[LeapFrog]

I am curious about a radio like the E.F. Johnson "Viking" Messenger 1 a.k.a. White-face, Loaf of Bread. In this modern time is it still legal for use?

I'm wondering if "all equipment" was "grandfathered in" or if my radio was manufactured before a certain date, then I am no longer allowed to run it on the C.B.?
My main concern is out of band Interference, or "spurious emissions".

Thank You

 

[scout943]

Cant see why it wouldn't be legal to use if its up to specs . Transmit and receive are crystal controlled ,if the crystals are good it should be fine to use only puts out 3 or 4 watts .

 

[nomadradio]

Fine print in the CB rules got expanded when the band was expanded from 23 to 40 channels. After a couple of years, it was no longer legal to sell a new 23-channel radio. Five years and it was against the rules to sell OR USE a used 23-channel radio.

Sounds stupid, but 40-channel radios have a much lower limits on how much unwanted or "spurious" RF energy can escape from them. There was no limit on how much RF could leak out of a 23-channel radio while receiving. To get approved as a legal 40-channel radio, there is a severe limit on this. The limits for transmit mode are a lot stricter than they were for a 23-channel radio.

This is not so different from the 'obsolescence" schedule that the FCC would declare for business land-mobile and marine radios in the 60s and 70s when performance requirements were tightened. They would generally give that industry 5 years at the most to upgrade their equipment to meet newer, stricter performance regulations.

And their approach to CB was pretty much the same.

And pretty much totally ignored.

73

 

[LeapFrog]

Fine print in the CB rules got expanded when the band was expanded from 23 to 40 channels. After a couple of years, it was no longer legal to sell a new 23-channel radio. Five years and it was against the rules to sell OR USE a used 23-channel radio.

Sounds stupid, but 40-channel radios have a much lower limits on how much unwanted or "spurious" RF energy can escape from them. There was no limit on how much RF could leak out of a 23-channel radio while receiving. To get approved as a legal 40-channel radio, there is a severe limit on this. The limits for transmit mode are a lot stricter than they were for a 23-channel radio.

This is not so different from the 'obsolescence" schedule that the FCC would declare for business land-mobile and marine radios in the 60s and 70s when performance requirements were tightened. They would generally give that industry 5 years at the most to upgrade their equipment to meet newer, stricter performance regulations.

And their approach to CB was pretty much the same.

And pretty much totally ignored.

73

Thank you NomadRadio

 

[KD8HMO]

You can use it, but restoring it to new condition will be a labor of love. Mike of Mikes Radio Repair specializes in restoring old stuff. I watched a video of him recapping and refurbishing an old Tram D201. He is very good at it.

 

[tecnicoloco]

You can use it, but restoring it to new condition will be a labor of love. Mike of Mikes Radio Repair specializes in restoring old stuff. I watched a video of him recapping and refurbishing an old Tram D201. He is very good at it.

As well as the tech who posted above your comment

 

[LeapFrog]

So gentlemen, if I replace the rectifier tube (12BW4) with a solid state rectifier even a voltage doubler, will
I then have to worry about any of the following:

*"Over Voltage"
*"Current Surge" (Do I need to add a resistor?)
*Re-biasing for the new B+
*Something about cold tubes, and filament warmers
(some people mentioned it's a "hard start" on the tubes, without the rectifier slowly warming up?)

There are varous mods that can be added to the radio to bring it up to
29.101.0 - Ten/Ten AM Net and improve the radio.

#1 - Remove the rectifier tube and under the socket, solder a voltage
doubler.

#2 -Remove the 12AU7A and replace it with a 12AX7.

#3 - Under the 7061, remove the 3,900Ω and replace it with a .33 mfd cap
at 600wvdc in parallel with a 390Ω 2w carbon resistor.

#4 - Now, you'll need to get 3rd overtone CRYSTALS. One for the transmit
and one 455 kHz lower for receive.

#5 - Now the only thing to do is to raise the filter caps capacity and wvdc.

This only works with the 117volt model.

GOD BLESS,
73,

Don/KA5LQJ

Thank You
73

 

[nomadradio]

Biggest thing you'll have to worry about is the effective voltage rating of electrolytic caps in the B+ circuits.

Here's the 12BW4 data sheet http://www.mif.pg.gda.pl/homepages/frank/sheets/106/6/6BW4.pdf

The spec of interest is the "Tube Voltage Drop", says 40 Volts.

Your normal silicon-rectifier diode is more like 2/3 of a Volt.

The extra 39 (or so) Volts might make an old filter cap uncomfortable. Running for years at the lower voltage it gets from the 12BW4 than it gets when a pair of silicon diodes are installed can cause a cap that checked okay to fail.

And if you replace all the filter caps, use new ones with a higher voltage rating than original. We tend to do that both because it doesn't raise the price of the repair enough to matter, and provides more safety margin, and a hedge against a breakdown later on.

Odds are this is all you'll need to worry about. Tube radios tend to be fairly forgiving about B+ voltage changes of around 15 percent. Old filter caps that have become accustomed to operating at the old voltage might not tolerate the voltage boost. If they are that old, it's time to replace them anyway.

73

 

[LeapFrog]

Thank You NomadRadio, this will be my first tube rig, I appreciate the information; I'm going to take my time restoring this radio, so I will install all new caps before turning it on!

 

[BBB]

Hope you get it on the air soon. It's pretty easy to work on.

I like the Messenger 223 better. Same radio guts turned sideways basically and with all 23 channels. Either one has nice warm t00b modulation.