Unusual PAL VFO

[CollinsMan]

I picked up this "B-1" PAL VFO a while back and thought I'd share a pic of it as they seem to be kind of rare - at least the ones with "XTAL MODULE" marked crystal jacks on the front. It has a 6.075 mc crystal plugged into it. I haven't been able to find out any information about this particular version. Have any of y'all ever seen/ used one?

 

[nomadradio]

The variable oscillator inside the PAL runs from 5 MHz to about 5.3 MHz. It mixes with that crystal to get you 11.075 MHz for channel 1, more or less.

The info for a Siltronix VFO made for 11.1 MHz says it should work with 23-channel Pearce-Simpson Cheetah or Simba, Cobra 138 or 139, Midland 13-893 or other radios that used that crystal.

Plugging in a different crystal will change the coverage range of the PAL, but only so much. The three tuned circuits inside are a bit narrow banded, and using a crystal more than 30 or 40 channels higher/lower would require repeaking those adjustments. Changing a PAL for an entirely new output frequency requires changing components inside to tune the new frequency range.

There were literally dozens of different crystal-frequency setups found in 23-channel radios. As a result, sliders built to substitute for those crystals were built with different output frequencies to match a particular radio's internal crystal frequencies.

73

 

[CollinsMan]

Thanks, Nomad! I appreciate the information. Though I've used Siltronix VFOs before, this is my first PAL. I like the nice gear system utilized in the dial. It seems to be especially well-made.

I'll look up the changes needed to get the PAL to work with my Sonar FS-3023 and modify it. I'll be converting the Sonar/VFO to work on 29 mcs, so some studying and parts scrounging are in order.

I could just use a DDS VFO. However, I like the look of classic CB equipment and think it all would work well on 10 meters AM. There's no real CB activity around here at all, or I would use it as made. A couple of locals run 10M AM, though. I'll be using the Super MaCo 300 up there, too. Should be fun - Thanks again!

 

[CollinsMan]

I was digging through some old downloads and found a pdf chart that explains the differences between the various PAL VFOs and how to add and remove parts to get them to do what you want. This information is from the original engineering notes.

 

[James Tinsley]

I picked up this "B-1" PAL VFO a while back and thought I'd share a pic of it as they seem to be kind of rare - at least the ones with "XTAL MODULE" marked crystal jacks on the front. It has a 6.075 mc crystal plugged into it. I haven't been able to find out any information about this particular version. Have any of y'all ever seen/ used one?

 

[James Tinsley]

The B-1 is for a Cobra 132 or 135 "B" series which I have. If unit is still original and not modified I would be interested in buying if you're interested in selling. I think the crystal in front is to replace the channel pulled when adding the VFO.

 

[nomadradio]

When the cost to restore a radio creeps up past the price of buying two or three newer ones that will run rings around it, I decline.

That's the story with the GE 3-5875 Superbase. Won't agree to fix one of those any more. Same with 23-channel AM only radios, the Realistic TRC-459 and other radios that have passed the 40-year mark. The 86XLR has reached the 45-year mark.

Just because you can, does it mean you should?

Not always. That 40-year mark is where the line between "repair" and "restore" gives way and disappears. If it were a 1977 auto under a tarp in a barn with 500 original miles, you would still need to replace a whole slew of gaskets, seals, belts hoses and such before it could be trusted. A person might wish to just "patch" what's broke in a radio that old, but it won't be reliable without being properly restored.

The issue of parts that haven't been stocked in 30 or more years makes it necessary to have a proper junkyard of parts radios. I explained that I had recently ditched every 85 and 86-type radio from the basement. We hadn't fixed one in decades, and they no longer justified the space they took up, so out they went.

Anyone who wants one of those fixed up should locate a guy with the biggest junkyard of parts-donor radios. We have been actively unloading shelves of pre-1980 radios, and the 86XLRs we had are gone.

Forever.

And they won't be coming back.

73

 

[AudioShockwav]

When the cost to restore a radio creeps up past the price of buying two or three newer ones that will run rings around it, I decline.

That's the story with the GE 3-5875 Superbase. Won't agree to fix one of those any more. Same with 23-channel AM only radios, the Realistic TRC-459 and other radios that have passed the 40-year mark. The 86XLR has reached the 45-year mark.

Just because you can, does it mean you should?

Not always. That 40-year mark is where the line between "repair" and "restore" gives way and disappears. If it were a 1977 auto under a tarp in a barn with 500 original miles, you would still need to replace a whole slew of gaskets, seals, belts hoses and such before it could be trusted. A person might wish to just "patch" what's broke in a radio that old, but it won't be reliable without being properly restored.

The issue of parts that haven't been stocked in 30 or more years makes it necessary to have a proper junkyard of parts radios. I explained that I had recently ditched every 85 and 86-type radio from the basement. We hadn't fixed one in decades, and they no longer justified the space they took up, so out they went.

Anyone who wants one of those fixed up should locate a guy with the biggest junkyard of parts-donor radios. We have been actively unloading shelves of pre-1980 radios, and the 86XLRs we had are gone.

Forever.

And they won't be coming back.

73

Agree with you Chris, at some point it is no longer feasible to work on a radio that has no replacement parts available anymore.
And with that many miles on it, even if you carefully go over the radio, when that other 40 year old component fails, You are the bad guy because it failed.
" but I paid you to fix my radio and it's broken again.
Too much headache ......

73
Jeff

 

[FenceMan]

When the cost to restore a radio creeps up past the price of buying two or three newer ones that will run rings around it, I decline.

That's the story with the GE 3-5875 Superbase. Won't agree to fix one of those any more. Same with 23-channel AM only radios, the Realistic TRC-459 and other radios that have passed the 40-year mark. The 86XLR has reached the 45-year mark.

Just because you can, does it mean you should?

Not always. That 40-year mark is where the line between "repair" and "restore" gives way and disappears. If it were a 1977 auto under a tarp in a barn with 500 original miles, you would still need to replace a whole slew of gaskets, seals, belts hoses and such before it could be trusted. A person might wish to just "patch" what's broke in a radio that old, but it won't be reliable without being properly restored.

The issue of parts that haven't been stocked in 30 or more years makes it necessary to have a proper junkyard of parts radios. I explained that I had recently ditched every 85 and 86-type radio from the basement. We hadn't fixed one in decades, and they no longer justified the space they took up, so out they went.

Anyone who wants one of those fixed up should locate a guy with the biggest junkyard of parts-donor radios. We have been actively unloading shelves of pre-1980 radios, and the 86XLRs we had are gone.

Forever.

And they won't be coming back.

73

As long as you get paid to your specs what does it matter the age of a radio ??

 

[FenceMan]

As long as you get paid to your specs what does it matter the age of a radio ??

I have I know 50 plus of the old 40 to 60 year old radios & wouldn't change a thing !!

 

[AudioShockwav]

I have I know 50 plus of the old 40 to 60 year old radios & wouldn't change a thing !!

That's great for a guy in the hobby that collects old radios.
However if you own a business you have to follow different rules.
The first is that you fix the 50 year old radio, send it back to your client and then another 50 year old part fails a week later.
He now wants the radio fixed under warranty because you just said it was fixed.
Do you see the point.


73
Jeff