2TX240
Ratchet Jaw
Its About Audio Quality, Not Audio Quantity
Posts: 54
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Post by 2TX240 on Jul 9, 2008 10:45:02 GMT -5
I was wondering...
are there any tube radios that didn't use crystals for the frequency generation?
I have been looking for crystals for my Blackface/Whiteface radios and the prices are getting stupid...
JAN: $22 each
International: $20.95 each
MH Electronics: $18 each
So I am looking at $36 - $44 per channel....
I was wondering, was there any tube radios that used a PLL, or at least a different crystal arrangement (like the older Solid State 23 channel rigs)?
I want to run tube radios on CB from the house, but the price of a set of crystals is more than I paid for each of the radios!
I am starting to wonder if a Solid state frequency generation setup could be wired into a tube rig, as a form of external frequency generation, an wired into one of the crystal channel slots.
Any thoughts?
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Sandbagger
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Post by Sandbagger on Jul 9, 2008 11:03:13 GMT -5
I was wondering... are there any tube radios that didn't use crystals for the frequency generation? I have been looking for crystals for my Blackface/Whiteface radios and the prices are getting stupid... JAN: $22 each International: $20.95 each MH Electronics: $18 each So I am looking at $36 - $44 per channel.... I was wondering, was there any tube radios that used a PLL, or at least a different crystal arrangement (like the older Solid State 23 channel rigs)? I want to run tube radios on CB from the house, but the price of a set of crystals is more than I paid for each of the radios! I am starting to wonder if a Solid state frequency generation setup could be wired into a tube rig, as a form of external frequency generation, an wired into one of the crystal channel slots. Any thoughts? Well, once upon a time, the FCC allowed any stable method of frequency generation. But practical consideration pretty much made crystals the de-facto standard. So pretty much any old 60's vintage tube rigs will be crystal controlled in some way. The PLL did not appear on the scene until the mid 70's right before 40 channel radios came out. There are a few PLL tube rigs out there, including the Robyn T-240, but generally speaking, by the time PLL's became the standard, tubes were pretty much past their prime and all but gone from the CB scene. The problem you are running into is that you have a less than 23 channel radio, which required a pair of crystals for each channel. If you find a synthesized 23 channel radio, the crystal complement will be somewhere around 12 to 14 crystals for all channels. If you like the white and black face Johnsons, look for a Johnson 223, it's virtually identical in circuitry except for a 23 channel crystal synthesizer. Since these vintage rigs are 30-40 years old, the crystals tend to drift off frequency so there will still be a need to replace crystals. I have a bin full that I pulled from junk radios over the years, and that usually helps. But I feel your pain. It's hard to justify paying $40 for a set of crystals to put in a $10 radio. As for external frequency sources, this is certainly doable, but it works best with a synthesized radio, since you only need to substitute one frequency. There are external VFO's to be had, as well as some digital PLL sources. Some of these may need a little creative engineering to adapt (I once used an old Kraco 40 channel PLL radio as a digital VFO for my SBE Trinidad). But for me, that's part of the fun. |
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2TX240
Ratchet Jaw
Its About Audio Quality, Not Audio Quantity
Posts: 54
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Post by 2TX240 on Jul 9, 2008 11:15:02 GMT -5
Cool info Sandbagger, Thanks
The Johnson 223 is tube and 23 channel?
I would love to hear more about your Kraco PLL as a digital VFO for your SBE. That is exactly what I was thinking..
I was wondering how I would pull off the 455khz offset on TX/RX...
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Sandbagger
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Post by Sandbagger on Jul 9, 2008 13:16:42 GMT -5
Cool info Sandbagger, Thanks The Johnson 223 is tube and 23 channel? I would love to hear more about your Kraco PLL as a digital VFO for your SBE. That is exactly what I was thinking.. I was wondering how I would pull off the 455khz offset on TX/RX... I got lucky. The main PLL VCO frequency in the Kraco is 37.xxx Mhz, which was right in the range that the SBE needed to see. So no major modifications were needed. Using 4008 adder chips on the PLL allowed my to "align" the Kraco's channel selector to agree with the SBE's channels. Trying to do this with a radio that requires a separate TX and RX frequency would be a bit tougher. If it were me, I'd probably do the 455Khz offset by diode switching the PLL chip with the adder chips to shift the VCO output by 455 Khz. But you then have to isolate/buffer the VCO output to the proper TX and RX oscillator circuits. It's a bit of work, but not impossible. Only you can decide if it's worth your time though. The Johnson 223 is a tube 23 channel synthesized radio. Talk to Spitfire 441. He has one. |
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2TX240
Ratchet Jaw
Its About Audio Quality, Not Audio Quantity
Posts: 54
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Post by 2TX240 on Jul 9, 2008 14:57:54 GMT -5
Ahh, I see... Well, I might have found a solution to the problem... FCC-2 Mk II www.norcalqrp.org/fcc2mkii.htmI purchased the original FCC-1/FCC-2 Kit last year, hoping to do the same thing, but it topped out at 21 Mhz. The new version will go to 31 Mhz... too bad it is out of stock at the moment... |
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Jul 9, 2008 16:57:22 GMT -5
Ahh, I see... Well, I might have found a solution to the problem... FCC-2 Mk II www.norcalqrp.org/fcc2mkii.htmI purchased the original FCC-1/FCC-2 Kit last year, hoping to do the same thing, but it topped out at 21 Mhz. The new version will go to 31 Mhz... too bad it is out of stock at the moment... Ooooooooh, I like that thing. But you also have to realize that the crystals in your radio do not run directly at 27 Mhz. They run at what's known as "Overtone" frequencies. The most common overtone crystals in older CB rigs are 2nd and 3rd overtone. What this means is that for a second overtone, you'd take the CB channel frequency and divide that by 2. Similarly a third overtone crystal freq would be the CB channel divided by 3. So you need either a 9.xxx or a 13.xxx Mhz frequency for your radio. It might make things a little easier....... |
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2TX240
Ratchet Jaw
Its About Audio Quality, Not Audio Quantity
Posts: 54
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Post by 2TX240 on Jul 9, 2008 21:07:58 GMT -5
Actually, the Messenger 1 and 2 run at Fundamental...
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Post by bioman on Jul 11, 2008 9:21:30 GMT -5
which rocks do you need???
i could look thru my bin here as well as the ones that my "old radio guy" has
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2TX240
Ratchet Jaw
Its About Audio Quality, Not Audio Quantity
Posts: 54
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Post by 2TX240 on Jul 11, 2008 9:52:35 GMT -5
Channel 13 Receive Channel 23 Transmit Thanks Scott. I am getting an server error while trying to enter the chat room  |
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Post by bioman on Jul 11, 2008 10:02:37 GMT -5
ok will check
ill hang out in the chat room for awhile if you can get in ...
otherwise check your PMs
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Post by spitfire441 on Jul 14, 2008 5:59:25 GMT -5
Actually, the Messenger 1 and 2 run at Fundamental... If that is true, why does my Messinger II have 13 mhz crystals? They run on 2nd overtone. |
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2TX240
Ratchet Jaw
Its About Audio Quality, Not Audio Quantity
Posts: 54
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Post by 2TX240 on Jul 14, 2008 7:28:13 GMT -5
Really?
I checked mine with it was running and the freq was 27.XXX...
The crystals are all stamped 27.XXX as well.
They run on 2nd overtone?
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Jul 14, 2008 8:27:55 GMT -5
Really? I checked mine with it was running and the freq was 27.XXX... The crystals are all stamped 27.XXX as well. They run on 2nd overtone? Most crystals will be stamped with the operating frequency on them. Some crystals will also stamp the fundamental freq on the side as well, but not all do. Most CB radio crystals (non-synthesizer) run at either a 2nd or 3rd overtone, which makes the crystal either 9.xxx or 13.xxx Mhz. If you ever get access to a crystal tester, they will show the crystal's fundamental frequency. It would appear that the "Black Face" runs at 2nd overtone according to what Pete said. |
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Post by bioman on Jul 14, 2008 13:40:54 GMT -5
well see if you can figure out which ones you need
ill go thru my "bin"
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2TX240
Ratchet Jaw
Its About Audio Quality, Not Audio Quantity
Posts: 54
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Post by 2TX240 on Jul 14, 2008 21:03:12 GMT -5
I found I have 2 good Channel 13 TX crystals...
I need a 13 RX!
Anyone want to swap 1? a TX for an RX?
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Post by spitfire441 on Jul 15, 2008 16:51:01 GMT -5
Really? I checked mine with it was running and the freq was 27.XXX... The crystals are all stamped 27.XXX as well. They run on 2nd overtone? Most crystals will be stamped with the operating frequency on them. Some crystals will also stamp the fundamental freq on the side as well, but not all do. Most CB radio crystals (non-synthesizer) run at either a 2nd or 3rd overtone, which makes the crystal either 9.xxx or 13.xxx Mhz. If you ever get access to a crystal tester, they will show the crystal's fundamental frequency. It would appear that the "Black Face" runs at 2nd overtone according to what Pete said. I do have a digital frequency crystal reader. Here is a 2nd overtone ch. 21 crystal thats old and a bit high in freq.  |
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2TX240
Ratchet Jaw
Its About Audio Quality, Not Audio Quantity
Posts: 54
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Post by 2TX240 on Jul 16, 2008 9:45:41 GMT -5
Interesting...
Thanks Spitfire.
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