The MOD

[mechanic]

I'm sure many of you remember the "MOD" where 'weakstation' came up with a control circuit using EPROMs to control the PLL and VCO. Lots of channels for different MB8719 chassis.
Pretty much forgot about this till today as I was doing a search for my old Geocities page. The front page is gone but some of the secondary pages still float around!
One of my pages I found to be connected to the old MOD page and thought I would add it here for at least posterity!

http://www.webring.org/l/rd?ring=spacecase;id=16;url=http://www.geocities.ws/cobra269/

It should work.....

I know there are more recent versions of channel expansions using Atmel ICs or others... but the old stuff is interesting!

73 mechanic

 

[Robb]

IIRC, there was a Yahoo group that was about The Mod.
Has disappeared since - tho . . .

 

[mechanic]

It is still there but not very active.....

https://groups.yahoo.com/neo/groups/the_mod/info

73 mechanic

 

[nomadradio]

The hard-wired EPROM technology at the heart of this setup is pretty well obsolete. Takes a lot of wiring, to boot. Really too many wires to build by hand without circuit boards

Modern-day equivalent products you can buy are mechanically a lot simpler, based on single-chip microcontrollers. Fewer chips, fewer wires. A guy in Austria named (I think) Gerhard Maurer makes a whole line of PLL upgrades. And another one in Australia has a setup that puts three digits behind the radio's channel windo.

Only way you can copy those to build your own is to obtain the internal programming for the microcontroller chip, or write your own. That's the one difference between the old way and the new way. The code contents of the 'weak station' EPROM chips was made available. The program code that runs the newer stuff is usually not circulated.

Progress giveth, progress taketh away.

73

 

[TheRealPorkchop]

Or buy one and copy it.

 

[nomadradio]

Ah, only if the "read protect" bit is not set in the chip's config register.

Everything we ever sold with a chip like that in it had the copy-protect bit set.

Causes a copy's program contents to be scrambled.

Who knows if those guys do this? Never have tried to find out.

73

 

[NZ8N]

I think the Negative Channel Number display is kind of hokey. If it said 6.81 (26.815) instead of -15 it would at least show part of the frequency, instead of reference to Channel 1.

 

[Shadetree Mechanic]

I wonder if one of those Arduino gizmos could be programmed and configured to do something like this? I have been interested in the Arduino but I haven't found a need to use it. Something like this would get me going maybe.

 

[TheRealPorkchop]

Ah, only if the "read protect" bit is not set in the chip's config register.

Everything we ever sold with a chip like that in it had the copy-protect bit set.

Causes a copy's program contents to be scrambled.

Who knows if those guys do this? Never have tried to find out.

73

True, kinda like burning an e-fuse. Those that know will catch what my comment meant though, open source project like this get copied a lot.

 

[nomadradio]

open source project like this get copied a lot.

Ahhh, isn't that the point of open source?

73

 

[TheRealPorkchop]

Yes. But again, those that know what I’m referencing will get my original post. It absolutely isn’t a slur or sling off against you my friend, and isn’t a contradictory posting against anything you said.

 

[TM86]

I wonder if one of those Arduino gizmos could be programmed and configured to do something like this? I have been interested in the Arduino but I haven't found a need to use it. Something like this would get me going maybe.

Yes, they can. I used an Arduino to replace the custom eprom/controller in a SBE Console V. Worked great.

Tried it with a Cobra 2000. I had the arduino talking to the PLL just fine, but never could get it to accept input from the channel selector without locking up. I'm sure someone smarter than me (meaning most people) could figure it out. Until then be prepared to replace your channel selector with a rotary encoder if you want to go this route.

 

[nomadradio]

isn’t a contradictory posting against anything you said.

Umm, okay.

Didn't really think it was.

Biggest obstacle to using the radio's original channel selector as the input to a microcontroller has to do with "pin economics".

The 7 wires from a normal selector take up 7 pins on the controller. An encoder takes two.

Besides, encoders are cheaper to make. A winning combination for anyone designing a consumer product.


73

 

[wavrider]

N3ZI has a kit or used to have one for encoder, programmable for whatever IF freq you needed, always thought about putting one in an old Siltronix just for the heck of it, never got around to doing it.
https://www.pongrance.com/DDS2018.html

 

[NZ8N]

Tried it with a Cobra 2000. I had the arduino talking to the PLL just fine, but never could get it to accept input from the channel selector without locking up.

I believe there might be a voltage difference between the channel selector (8v?) and the input lines you use on the Arduino (3.3v or 5v). You would need some type of voltage translator on each line to buffer the difference.