VFO sideband turning question

[darticus]

VFO sideband turning question.
I have a Browning Mark 3 CB. The person who sold it to me said they added a capacitor to the VFO to allow much more turning so hey could talk on half channels on side band. It sounded to me that he was saying two people would go to channel 38 AM go to USB or LSB and tune the VFO to get to a section where they can talk mid way on the sideband channel. This technique was used back around 1970. He now says your better removing the cap as this makes it very hard to stay tuned. He said to get someone to do it but I don't know what he's really talking about. I see a cap that was added to the VFO knob and this is probably the cap he is talking about. He doesn't know where it is. WE ARE NOT REALLY TALKING NOW AS HE APPEARS VERY AVASIVE. Does anyone know what he is talking about? Can I enjoy using this if I new what I was doing. Is anyone familiar with this half channel technique. You would probably have to be from back in the day to remember this. I found a link that might have something to do with this. here it is but I don't know if its connected to what I'm talking about. qsl.net/n3is/oscillator.htm Thanks Ron

 

[pjtnascar]

The article you linked to seems to explain how to tune with a dual VFO. The previous owner probably changed the value of the capacitor to extend the offset range of the VFO (clarifier). I would try the radio out on sideband and see how difficult it is to tune on frequency. If you can tune it in fairly easily, and it remains on frequency as it heats up, then I'd leave it alone. If you want to put it back to original, trace pins on the VFO back using the schematic. Most likely, it will be the capacitor or resistor closest to the knob (potentiometer) itself. When you find the component that does not belong, or is not the correct value, that is the culprit. It seems that anytime someone unlocks the clarifier on a radio it is a little more difficult to tune in on sideband. If you haven't already, I'd try th radio out with someone nearby to see how easy it is to tune in, and how stable the radio is.

 

[darticus]

This is what the original owner had to say about this mod.-"The VFO slider that is installed let's you go 10,000 up or down, it was installed back in the 70's because it was so busy on regular channels we could all go beyond any other radio in the day. The newer radio's can all get there now and it's not busy enough to need." It, I think, will be fine without removing but it might be a pain to tune. Will test and see. Ron

The article you linked to seems to explain how to tune with a dual VFO. The previous owner probably changed the value of the capacitor to extend the offset range of the VFO (clarifier). I would try the radio out on sideband and see how difficult it is to tune on frequency. If you can tune it in fairly easily, and it remains on frequency as it heats up, then I'd leave it alone. If you want to put it back to original, trace pins on the VFO back using the schematic. Most likely, it will be the capacitor or resistor closest to the knob (potentiometer) itself. When you find the component that does not belong, or is not the correct value, that is the culprit. It seems that anytime someone unlocks the clarifier on a radio it is a little more difficult to tune in on sideband. If you haven't already, I'd try Th radio out with someone nearby to see how easy it is to tune in, and how stable the radio is.

 

[potbellyperch]

you unlock it so you can slide to 10 instead of 5s =0 but you have to have a ear to get it rite &
be on freak....

 

[JayMojave]

Hello Darticus: Modifying the radios to slide, more than a few KHz was a big thing back in the 60's and 70's. But not now as newer radios are more stable, and there are less users out there.

I modified a older tube radio to increase the slider or clarifier to tune to a wider frequency span. I removed the mod and kept it stock to allow a stable frequency operation.

Pjtnascar, gave you good advice.

Jay in the Mojave

 

[darticus]

Thanks for the great info. I will change back to original if I can do it without making an error. For now let it be. Thanks again Ron

 

[kb2vxa]

Slider refers to a true VFO in CB terms, the little knob for tuning in SSB is called the clarifier or in some older cases delta tune. It should only affect receive, it's illegal for transmit because it can result in off frequency operation. Back in the daze some modified them to shift frequency farther than allowed so they could operate on "half channels" that are actually Class C radio control channels spaced at odd intervals between the Class D voice channels. That's what going to a quiet channel on a crowded band was all about, not going between channels as no CB has enough selectivity to split them without bleed over from either side.

Like the man said it's rather useless today as there is plenty of room to talk since the fad is long over.

"I modified a older tube radio to increase the slider or clarifier to tune to a wider frequency span."
So what? I used something a lot better. <razz>

 

[mike_gain]

Lots of folks modified the clarifier on ssb rigs for transmit and to extend the sliding range past the 2 to 3 khz from the factory. 5 khz on each side would allow operators access to the "Zeros", say it in your best southern draw Zeerows. It is literally halfway between any two cb channels. Some did mod them for more khz on say the + side to access the Class C R/C channels mentioned above. Most installed a switch for a 10 khz drop to obtain these though. These mods worked in any mode not just ssb.

 

[k3cfc]

Lots of folks modified the clarifier on ssb rigs for transmit and to extend the sliding range past the 2 to 3 khz from the factory. 5 khz on each side would allow operators access to the "Zeros", say it in your best southern draw Zeerows. It is literally halfway between any two cb channels. Some did mod them for more khz on say the + side to access the Class C R/C channels mentioned above. Most installed a switch for a 10 khz drop to obtain these though. These mods worked in any mode not just ssb.

Yes mike gain you are exactly right. good job on the correct answers.

K3CFC

 

[kb2vxa]

All except one and here it is.

"Most installed a switch for a 10 khz drop to obtain these though."
That would put the rig on the next lower channel, they're spaced every 10 with no guard frequencies between them. Perhaps you're thinking of the expanded PLL chip that gives those "extree channels" on which many overlooked the last fixed pin. That set the frequency steps defaulting to 10KHz but when the logic level is changed gives 5KHz steps.

 

[JayMojave]

Hello All: In the old 23 Channel days of CB, CH 16 LSB was mostly used as the SSB CB Channel, it was 20 Kc above ch 15. which was 27.135, so CB CH 16 being 27.155 Mc.

So being able to "slide down" to 27.150, 27.145, and even 27.140 Mc was the hot thing at the time. But few could make these lower channels. So Amateur Radios were bought and used, which also open up many of the channels above CH 23. And got a lot of operators into Ham radio.

Jay in the Mojave (We Like IKE CVN69)

 

[darticus]

Great info. That explains it. Ron

Hello All: In the old 23 Channel days of CB, CH 16 LSB was mostly used as the SSB CB Channel, it was 20 Kc above ch 15. which was 27.135, so CB CH 16 being 27.155 Mc.

So being able to "slide down" to 27.150, 27.145, and even 27.140 Mc was the hot thing at the time. But few could make these lower channels. So Amateur Radios were bought and used, which also open up many of the channels above CH 23. And got a lot of operators into Ham radio.

Jay in the Mojave (We Like IKE CVN69)

 

[mike_gain]

I guess I should have been more specific in my previous post. My mind was awash with old memories from yesteryear. It doesn't take much to send my brain on a mini vacation. The 10 khz drop switch was in fact used mostly in the PLL rigs to obtain the "A" channels. However a 23 channel non PLL could have a 10 khz drop or forward switch. You could have added the crystal series number missing, usually 4 crystal bank to 5 and toggle between two. If you switched between the 3rd and the added crystal it would be a 10 khz forward. If you switched between the new one and the 4th it would be 10 khz down. I always opted 10 khz up because the "A" channels were easy to remember...3A, 7A, 11A, etc. Just turn to channel 15 flip the switch, taadaa 15A. I hope this is not to confusing, It's been a very very long time since I've dabbled with cb. Merry Christmas everyone.

 

[kb2vxa]

OK, now I see what that 10Kc drop was about before they changed it to KHz. (;->) Those crystal synth rigs pre-PLL were easy to figure out, the selector switch used one crystal against four stepping up to the next working against the same four. I remember the Lafayette Comstat 23 that had 22A right on the dial between 22 and 23. The FCC didn't take kindly to it and out came the 23A with the channel cut out, we fixed that by bridging the gap. I think it was the 23B that had 22A and B in it at first, later models didn't but we fixed that too. Sets with tunable receive were the best, we just moved the last crystal socket to the front panel and plugged in any crystal we wanted.

"So Amateur Radios were bought and used, which also open up many of the channels above CH 23."
They opened a whole lot more than that, see my post above with the picture. FYI the receiver has 11M on it but the transmitter doesn't but tuning the 40M VFO section down from 7MHz to 6 dropped 10M down to 11. Finding the frequencies was not a problem, with the receiver already there it was easy with the little red spot button below the meter.

"And got a lot of operators into Ham radio."
Could be but I wasn't one of them. When CB went to hell in a basket I sold the station and left the air but remained in the scanner hobby for many years. Then I came across a couple of CBers I knew become hams and they rather pushed me into it, no regrets since the world opened up to me which it never did back in my CB daze.

So why are you so confused by this CB outlaw guiding CBers in the right direction and away from illegal operation? A leopard can't change its spots but a radio operator can change his ways.

 

[mike_gain]

Another way to obtain 22A was to swap the last crystal, the one for channels 21, 22, and 23 with say the first crystal that controlled channels 1, 2, 3, and 4. 22A would fall in the channel 3 slot. You would lose channel 3 because it would fall in the PA slot between channels 22 and 23. I did not heed the need to jump to ham back then either. I finally made the jump in 1990 and have not looked back. The best thing about cb is it is a great marker for 10 meter band openings. However, I will always have a soft spot for cb memories. I would love to have a Hygain 623 base, I might even talk a little ssb.

 

[k3cfc]

Back in the day when i ran a Lafayette he 20t if you switched the ch 11 crystals you would be on civil air patrol frequency. found this by accident.

K3CFC

 

[kb2vxa]

The Hallicrafters CB-3A had a neat trick, the receive crystals were 10M cuts so just put them in the transmit slots and re-tune the transmitter. The receive was easy too, tweak the tunable up to 10 and re-tune the RF amp. Just as a quick experiment I called CQ with a modified genuine Novice callsign and had a nice QSO with a station in the Georgia Republic. Back then most was AM BTW. That was a quick one shot deal, the FCC monitoring station in Alegian (sp?) Point, Michigan was quite active passing out pink slips.

Those were the days of simple circuits, mods, "tweaking and peaking" did some interesting things and radios still worked properly. Crystal synthesis was the first reason to keep your golden screwdriver out of it, the traps were barely distinguishable from things you could adjust and required sophisticated equipment to align. One slight mistake and you had receiving and transmitting spurious responses all over the place. The more complicated they got the worse they got, countless radios have been ruined by the truck stop commandos but this is not the place for one of my pet peeves.

 

[JayMojave]

Hello All: Yeah the CAP HF Frequencies were and are: 26.620 and 26.617 Mc per Monotoring Times Top 1000 Frequencies. One of the locals found this by accedent, as he was experimenting around with different crystals and such. He got barked at from some CAP guy on 26.620. This is 455Kc down from CH 10 27.075 Mc. Big Bob soon became a monitoring memeber of the CAP.

Some CB radios had a space or blank between ch 22 and 23, and some also between 21 and 22. This blank spot on the channel dial spured more investigation into oscillators and mixers than a lot of books and such.

The Layfettee HB444 Radios came with 22A and 23A from the factory. But the FCC told the manafacture to stop this. General Radiotelephone in Burbank Ca, on Burbank Blvd ( I was there a few times as I set my dear ol dads Super MC-11A Radio on fire and needed repair) had a CAP channel spot between ch 1 and ch 23 in the dyas. This was used for that secert channel just the inside groups would use. And many older CB radios has a crystal socket on the front of the CB radio for transmit. I had a old tube CB that had to have the transmit crystal taped into the socket so I could transmit, or it would fall out.

Jay in the Mojave

 

[kb2vxa]

Too bad you didn't know the trick of using a pin to bend the crystal socket pin sides back together.