Open source hardware mods?

[LoyalServant]

Your old tram could benefit from an outboard PLL, or better yet, you could build a switching board and some logic to convert a standard rotary switch to the sequence required to step the mixing crystals. I am thinking some small reed relays and some TTL chips to drive them from a BCD rotary switch. Of course a PIC could be programmed to do this switching nicely.

The PLL would obviously be superior... but barring that....

Mods that I have seen are guys doing it wrong... you can't stuff crystals on a rotary switch with a few caps on 8 inches of wire.... it might "work" but it's wrong..... and horridly... poor engineering....
In fact if you look at the Tram schematic they are doing the switching PROPERLY!

Reed relays are pricey for what they are and I am sure that a Colpitts oscillator and proper switching can be achieved as they are doing on the Tram mentioned. To emulate the rotary control they have there you would need 4 x 8 bit shift registers..... 74HC595 would do the trick nicely.
You have to handle mode changes as well and you should be able to send all 4 bytes in at once so you only need at minimum 3 pins to drive the 595s.(clock, data, latch)

In fact my MCU controller mentioned above could be modified for such a purpose fairly trivially.

Once your getting the desired set of frequencies to mix... inject those and your done.
Out of curiousity I went to ebay and I see these Tram D201s..... are NOT CHEAP. WOW.

In fact I wonder.... LTC6904 - 1kHz - 68MHz Serial Port Programmable Oscillator - Linear Technology
HMMMM...

 

[RFI-EMI-GUY]

I think the freq error and jitter of the LTC6904 might be a problem.

That said, a board with on-board PLL and VCO along with an MCU to do channel selection and fancy stuff like scanning and FHSS might be interesting. The "mod" would be to disconnect the on board frequency generation and tack in a couple coax cables to inject the new world. Control could be a shaft encoder knob with a momentary switch to enable features and modes. No need to drill more holes. The display could either fit in LED hole that exists, or have an S meter replacement that both serves as bar graph S meter and displays channel and mode info.

Though looking at the Tram Titan D201A, it might be nice to retain all the original features as closely as possible.

The PLL would obviously be superior... but barring that....

Mods that I have seen are guys doing it wrong... you can't stuff crystals on a rotary switch with a few caps on 8 inches of wire.... it might "work" but it's wrong..... and horridly... poor engineering....
In fact if you look at the Tram schematic they are doing the switching PROPERLY!

Reed relays are pricey for what they are and I am sure that a Colpitts oscillator and proper switching can be achieved as they are doing on the Tram mentioned. To emulate the rotary control they have there you would need 4 x 8 bit shift registers..... 74HC595 would do the trick nicely.
You have to handle mode changes as well and you should be able to send all 4 bytes in at once so you only need at minimum 3 pins to drive the 595s.(clock, data, latch)

In fact my MCU controller mentioned above could be modified for such a purpose fairly trivially.

Once your getting the desired set of frequencies to mix... inject those and your done.
Out of curiousity I went to ebay and I see these Tram D201s..... are NOT CHEAP. WOW.

In fact I wonder.... LTC6904 - 1kHz - 68MHz Serial Port Programmable Oscillator - Linear Technology
HMMMM...

 

[LoyalServant]

I have been able to source LCD modules to replace the channel display in the 148 and most other mobile radios. I can probably get some to fit in others.

This is what I have been running in my car for about a month now...
I took this about a month and a half ago I think....

imgur: the simple image sharer

Looks good to me!

And yep... that's a REAL 1Hz resolution counter.......

 

[RFI-EMI-GUY]

Pretty sharp upgrade!

 

[LoyalServant]

Thanks.

That was revision 1.
The next one that I may have in a week or so will have a more stable counter (I hope) as well as more roger beeps, scanning, etc.
The counter in version 1 also did not account for mode changes, so it would shift +/- 1.5Khz depending on the sideband. That's taken care of by monitoring the mode the radio is in now and doing the appropriate math.

This sits in between the TX line and the radio for the beep.
The very first one I used a crude method of monitoring the TX line using a pin change interrupt to set a variable and depending on which way it was being set triggered the beep as well as an additional hold on the TX line to play the beep... but it pulsed the TX line when you let go of the mic and it was detectable in the transmitted audio.

When the mic was released the TX line was pulled back up, and the MCU detected this, so it pulled it back down again and the delay between the time that you let the mic go and the MCU pulled it back down again varied from 1 to 2 milliseconds.. the radio can't change TX/RX states as fast as the MCU can...

I get the boards probably next week from the boardhouse so we will see what bodges these need
This version also has a TCXO instead of a won hung lo crystal @ like 200ppm.
http://www.foxonline.com/pdfs/fox924.pdf

It's not as accurate as my Agilent 53181 (duh ) but it works for a CB.