more old stuff

[billcreller]

An aviation friend, who is also a ham radio guy, brought me an old Hallicrafters (sp) Citizens bad radio,  "because it has tubes in it "      I think he picked it up at a "ham fest" where all this stuff is traded & sold.

Not sure what vintage it is, but it's 12 volt, and has a vibrator power supply.     Likely one of the first when the CBs came out ?
 It has a bunch of crystals in it for the band switching etc. and reminds me of early aircraft transceivers....

Anyway, the case is kinda cool, and might make a cool amp head.
I'll get some pics of it.....

[kagliostro]

We are waiting for it 


K

[TIMBO]

K, Don't be so pushy, I'm sure he's going to post them soon............................ WELL.........

[kagliostro]

Ciao TIMBO

 

Franco

[billcreller]

I'll get some.......just remember, I'm old & slow

[EL34]

Git-R-Done Bill


Sounds like a cool project carcass?

[PRR]

> Hallicrafters citizen CB-1

If it really is a CB-1....

I only have the "fixed" 115VAC only plan, but likely the 12VDC/115VAC model is similar except for added vibrator.

It "is" a guitar amp except some switching. You can switch a microphone to the power amp, but then the power-amp OT gets un-grounded from the speaker. Jump the green wire to ground, speaker is always-on. Slam/jam T/R switch to Transmit.

Oh, and pull the 6AQ5 so you are not leaking on the CB band. (Is anybody still there?)

There is a power transformer (but be sure of this! Hallicrafters made a few death-trap hot-chassis radios). Raw B+ is 230V. Audio power amp is 6K6 and gets about 180V-200V. Power output is around 1-1/2 Watts.

As a guitar-amp, it is ol-school and low-fi. Grid-leak biasing, lots of small caps to trim treble (and RF trouble), some not-large caps to shave bass (more speech-punch for your transmitted Watt).

The 6CS7 tube is a real oddball. I think it was a dump on the market, a TV V-sweep for smaller CRTs which went obsolete as larger CRTs flooded the market. You could do this or that, but at some point you might scrub all the small audio and re-wire a 12AX7 system.

[billcreller]

Thanks for all the info !



Here's one pic....

and the back side...





the top , from the front....

[billcreller]

There are two cords with it, one has a Ac line (110 VAC when it was built ! ) and a 12 volt cord.  Both have a Jones plug on the end, that can plug into the receptacle on the rear of the chassis.

here's the front...




The top cover is hinged on the back, and is held closed with latches on the sides...

So, that transformer must be wound to use with the vibrator, or the  AC line voltage ??

And like you said PRR, there are some weird tubes in it !

I haven't removed the bottom cover yet......I need a bigger work bench....

[Ritchie200]

Wow!  An eight channel!  That would have been the stuff back then.  Those old tube rigs used to splatter pretty bad in the 70's.  By then most had been used and abused.  Only the Browning and Robyn tube fans seemed to stay with them - at least around here.  Man, I just love those old radios - any old radios!

PRR, yeah there are still some diehards on CB, but nothing like it was.  Many are buying older Icoms, doing a simple all freq mod, and running 100 watts and/or linears at +++  Now that the FCC dropped the code test for Ham, I don't get it.  I guess its that pirate radio mentality.  Early evening/morning when the skip rolls in you can hear them.

Jim

[billcreller]

I learned Morse in the military ( a really long time ago ) and barely remember any of it ) 

[PRR]

CB-3 is a later model, with more crystals, and different odd tubes.

Nominally 6DC6 6BE6 12BA6 6AZ8 6BN8 12AQ5 6AW8A

It also smells like they pushed closer to the CB limit of "5W DC input".

Mike amp is pins 798 of 6AZ8. Audio amp is 987 of 6BN8. Audio power is 12AQ5.

Transmitter is both sides of 6AW8.

You need the transmit relay energized but the transmit tube yanked, and the OT lead to the relay yanked and grounded to speaker.

Yes, the one PT has both 120V AC and 12V vibrated DC primary windings. If your cords are in good shape, you are good to go. At 12VDC it sucks 4 Amps (4.3A if transmitting).

DC power is a voltage doubler, 285V raw.

In 117VAC mode the heaters are fed from the vibrator winding. Heaters are series/parallel to arrive at 12V.

There is a tap from the heater power to the mike socket, probably to feed a Carbon mike. This would also explain the fairly low audio gain (carbon mikes are strong).

The audio power in CB-3 seems to be more like 3.5 Watts. This is odd because it is a LOT for a four-inch speaker, and more than the transmitter wants. The limit on RF output is specced as a limit on the DC into the RF final, 5 Watts Max. While a class C stage "can" be 99% efficient, for realistic devices we get 80%. So 4 Watts RF output. Plate modulation requires audio power of half the RF power. 2 Watts would be ample. (The 1.6W audio of the CB-1 was not pushing the laws.) 2 Watts would also be ample for a four-inch speaker and any reasonable radio shack. Dunno why they run the audio final at 9 Watts Pdiss and likely 3.6W output.

[billcreller]

Interesting description of how it all works.  I have no experience with transmitters except a bit with aircraft solid state types.

 Most of those are in the 5 watt range these days, but King Radio had one, A KX-160, which I believe had tubes, that put out 20 watts.  Kinda over kill I suppose...

We did have a transmitter in the military, that the army let the ham radio guys use.  It was a BC-610 as I remember. Don't remember the power it had, but we heated cans of beans on top of it when those tube got red.!

And in regard to more old stuff,  I just gave an old Echophone EC-1 to my ham radio buddy, for his collection.  Not sure when it was built, but I've had it since I was a young guy....

[PRR]

> transmit less than 5 watts

Best re-read the FCC. There's thousands of pages.

Unlicensed operation is mostly specified by Field Strength. This requires precision measuring.

Typical unlicensed rigs run under 100mW into too-small antennas. Far short of "5 watts". More like those things that put your iPod into your car radio.

The CB band has its own rules. At the time these rigs were made, the limit was 5 Watts *DC Input* to final stage. Why DC Input? Because RF Output is a tricky thing, DC Input is simple.

When these were made you had to register with the FCC (no test). Some time later the FCC gave-up, and I *believe* he can work this thing on-air with no formalities. (If higher wall-voltage has put it up to 5.1 Watts DC Input, he won't stand-out.)

However it is AM (DSB) only. CB has gone to SSB operation to get double the channels. His transmissions can be understood by modern SSB rigs; however he will be stomping on both Upper and Lower sidebands which is impolite today. However he can not understand SSB transmissions, which spoils the point.

As you can buy much better 27-ch SSB rigs for $20 at any ham-fest, I don't see much point in putting it on the air.

[PRR]

> the army let the ham radio guys use.  It was a BC-610

That was originally a Ham radio, adapted for military work. About 300-400 Watts out and about 500 pounds.