asking about the 23 channel radios?

[hillbilly1987]

hey guys just out of ceriousity why is there a blank spot in the middle between channel 22 and 23 just wonderin 73 redneck

[Sandbagger]

May 25, 2008 15:06:47 GMT -5 @hillbilly1987 said:

hey guys just out of ceriousity why is there a blank spot in the middle between channel 22 and 23 just wonderin 73 redneck

Well, the reason for the blank spot is because 6X4=24 and not 23.

The way a 23 channel radio's crystal synthesizer works, is that it mixes a set of 6 master oscillator crystals with another set of 4 to get the 23 channels. But since 6X4=24 that blank spot is an extra channel. Back when the 23 channel radios were state of the art, that blank spot channel was known as "22A". Today it's channel 24. Since that channel wasn't legal to use back then, it was defeated inside the radio. So if you go there, the channel will probably not work. But with a little micro surgery to the channel selector, it can be made to work again.

[hillbilly1987]

OOOO ok i get it now and that is cool and now i understand and thank you very much 73 redneck

[blacksmoke]

If anyone does this, a tech article would be greatly appreciated.

Thanks!
- JR

[Sandbagger]

Jun 3, 2008 21:44:11 GMT -5 blacksmoke said:

If anyone does this, a tech article would be greatly appreciated.

Thanks!
- JR

Does what? Adding channel 24 to the blank spot on a 23 channel rig? It would be difficult to do "step-by-step" instructions for this because the mechanism for defeating the channel varies between the various radio models. Some are as easy a clipping a single wire. Others require a means to bridge a gap (or 2 or 3) on the channel selector switch itself. Newer 23 channel PLL rigs can be even more "interesting" as there is sometimes a totally different channel sitting in the blank spot when you remove the defeat (On the Hy-Gain 623, it's 19"A" 27.195, on the Realistic TRC-152, it's 15"A" 27.145 for example).

I did write up an article about this on my website. Mostly it covered the history of this mod and why on a very high level.

A quick link to it can be found here.

[blacksmoke]

Thanks for the links there sandbagger.

[Tombstone (R.I.P.)]

I would tend to agree with Sandbagger, explaining how to do that will depend on the model of radio and how it's set up. I have a 23 channel Midland transistorized base radio here that the blank position on the rotary tuner is marked for "PA". I disconnected the PA feature and mounted a switch on the rear of the radio and soldered the two crystals for channel 24 and 25 on it then connected that into the rotary tuner. Then a bonus appeared, I found that, I think, every four channels you get a 10 KC jump when in one of those positions. Might have connected a crystal onto the tuner too but I can't remember because the radio just sits here since I don't use it. When it came in it had bad final and final driver transistors. I replaced those and the radio works well but the final transistor gets so hot that you can't touch it. I checked the voltage on the final and it's OK so I talked on the radio for about an hour and a half and it held in there. I even double heat sinked the final transistor, kinda weird.

Tombstone

[spitfire441]

Another way to get channel 24 on some 23 channel radios is it was never defeated. For example, the B&K Cobra CAM 88 and Cobra 98 as well as my Poly Comm 23 all have ch 24 already in the blank spot. I suppose back in the day folks respected the rules/feared the FCC and just didn't use the blank spot.

[Sandbagger]

Jun 5, 2008 6:29:52 GMT -5 spitfire441 said:

Another way to get channel 24 on some 23 channel radios is it was never defeated. For example, the B&K Cobra CAM 88 and Cobra 98 as well as my Poly Comm 23 all have ch 24 already in the blank spot. I suppose back in the day folks respected the rules/feared the FCC and just didn't use the blank spot.

That's very true. The first radios didn't defeat the blank spot at all. It would be interesting to see if there is a little blurb in the owner's manuals about not using that spot as the only "defeat" mechanism.

Heck and talk about trusting back then, the Lafayette Comstat 25 was made with TWO extra channels before approval to use them was even granted (and it never was).

[crazybob]

My Robyn T123B has CH. 22A (24) on the blank spot. Back in '73 My Comstat didn't have the blank between 22 & 23. You had to rock the selector back & forth to hear the "secret" channel!

In 1975, I took my Browning SST mobile apart & found a notch cut out on the inside selector round wafer thingy. I filled it in with solder & filed it down. ..Now I was on the secret channel!

[Sandbagger]

Oct 6, 2008 15:30:55 GMT -5 crazybob said:

My Robyn T123B has CH. 22A (24) on the blank spot. Back in '73 My Comstat didn't have the blank between 22 & 23. You had to rock the selector back & forth to hear the "secret" channel!

In 1975, I took my Browning SST mobile apart & found a notch cut out on the inside selector round wafer thingy. I filled it in with solder & filed it down. ..Now I was on the secret channel!

Yea, back in 1974 or so it was a sign of status to have the "A" channel. The few who did would go there to have "secret" conversations. What they didn't realize though was that anyone with an old rig with a tunable receiver could very easily tune that channel. So while not everyone could transmit there, a good many people could receive it......

[Kentucky Jim]

Anyone know if the SBE Console II SSB Base has it???

[Sandbagger]

Dec 13, 2008 23:28:04 GMT -5 Kentucky Jim said:

Anyone know if the SBE Console II SSB Base has it???

Yes it does, and it's not that hard to re-enable. Just cut one jumper and add another IIRC. No need to fill in gaps on the selector. It's one of the easier radios to do. Now the SBE Cortez, on the other hand, was a a real bear.........