Converting my AR144 to cover 555

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RD250
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Re: Converting my AR144 to cover 555

Post by RD250 »

OK I googled the EPROM book as Paul suggested and found a free download link and looked up this mod.

What a mess.

I hope to god nobody ever tried to build this because it is full of errors.
Not only is the circuit dreadful (with obvious voltage level errors for some parts) but the pinouts are confusing because they used a 24pin skt for the 22 pin PLL chip. Even then they screwed up the pin numbers beyond this on the schematic.

The PCB layout is poor. The RF decoupling is poor.

IMO there's no way the PLL would lock for the reason I gave in my previous pos about the phase detector. So I sat down and read all the text in the article and it says (very helpfully) that no one has ever tested this mod.

F*** !!!
I just wasted a lot of confusion over this crap.

[Rant Alert]
Why is it that pretty much every piece of CB related documentation I see is plagued with errors?
A lot of the 'homebrew' schematics on CB tricks have errors and nobody seems to spot them or correct them.


I can suggest a way to mod this radio over to a 145106 and it would effectively make the PLL the same as a mk2 148 so easier to understand and would allow 120channels + splits and UK40 if you used an EPROM and added an FM board as well. If anyone is up for it I can expand on this further but please, please ignore the mod info in the EPROM book :(
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Re: Converting my AR144 to cover 555

Post by MM1EWA »

RD250

I for one would love to hear how you'd go about this mod, my initial idea was to shoehorn the 145106 somehow (lets hear your suggestion for the somehow :-) ) then use something like the digimax lite board from OZ to control the channel/band selection.

Digimax appeals for 2 reasons, its saves having to mess about installing binary adders or retro fitting existing channel selector circuit to the new PLL, also it the digimax handles bandswitching itself.

So I know what I'd do, I just don't know how to do it, would love to hear how you'd put in the Mc145106.

Cheers

Michael - MM1EWA
RD250
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Re: Converting my AR144 to cover 555

Post by RD250 »

OK, well this is the way I would do it using old school CB tech rather than putting a whole new synthesiser in.

Note this is purely based on a quick look at an old Cobra 146 schematic. So that's my disclaimer :lol:

Obviously remove the uPD2824 PLL chip
I would remove the 10.24MHz crystal from the three coil VCXO on the existing mainboard and fit a 15.36MHz crystal here. It may need some tweaks to component values to get this to oscillate and tune as desired.

You can probably guess the rest...

But here it is anyway.

I'd build the 145106 on a tiny PCB that sits snugly over the area of the old chip with nice short connections. Also fit a 10.24MHz crystal to the 145106 for its reference using its onboard oscillator feature.

Then simply wire it up so that the 15.36MHz from the mainboard VCXO gets rerouted to the main board loop mixer to beat with the VCO to give the downmix for the PLL chip. All this stuff is already on the mainboard.

This is the same approach as a 148 but you add codes to the EPROM for each new block (no need for 4008 binary adders).

You would have to bin all RC components associated with the old active loop filter including the pullup resistor and simply fit a passive loop filter based on the one in a 148 but it will need the values tweaking.


You don't have to use a 15.36MHz crystal, you could use a 15MHz one from an old 148 if you use an EPROM to produce the correct codes for this. Or any crystal in the range and simply correct with the EPROM.
Once you do this you can add codes for blocks and splits as per a 148 but via the EPROM rather than needing binary adders.

I guess I'm as guilty as the EPROM Data book for posting up untested mods but this is just a suggested way of doing it.
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Re: Converting my AR144 to cover 555

Post by RD250 »

One slight issue with this would be that the PLL chip would be running from 5V and this restricts the VCO tuning range via a passive loop filter so you might be wise to fit an active (but non inverting) loop filter to get more tuning range. Depends how many channels you want.

Also, it's probably best to avoid using the 15MHz crystal from a 148 because this will push the division ratio down very low if you wanted to fit LOW band. So best to stick with 15.36MHz or something slightly higher.

This is because there may be issues with loop stability on the LOW block.

IMO it isn't worth doing TBH unless you really like these radios. Otherwise just buy a 148 or a Stalker 9. If you look back further up this thread you can see I modded one of these back in about 1984 to add the high block using a three coil osc board and that was much easier than swapping out the PLL. I guess it depends if you want the splits and LOW band as well?
Last edited by RD250 on 12 May 2011, 16:38, edited 1 time in total.
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Re: Converting my AR144 to cover 555

Post by RD250 »

But then im not the one to ask about Eprom's as im still on the steping stone's of learning about it all I can copy them so im geting there one day i will get it all im me head ..........
There's a bit about EPROMs in that EPROM data book but some aspects of the presentation may put people off.

I don't do much with external memory chips these days but there are better editing tools available (like maybe 25 years old) that would make the preparation of the EPROM data much easier to understand and manage.

What you don't want to be doing is writing raw HEX directly at each EPROM address with a hex editor as that is hard work. This seems to be the approach in that book :(

You can use text based files to prepare your data and create the data file for the programmer.

You can even add comments and use non hex umbers and the tools will do all the hex conversion and addressing for you. If you want to know more I can post up some info about these tools and how they make life simpler.
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Re: Converting my AR144 to cover 555

Post by Ashtec »

Please do as it's driving me mad trying to understand how to program Eprom's.....................

;) ;) ;) ;) ;) ;) ;)
RD250
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Re: Converting my AR144 to cover 555

Post by RD250 »

Ashtec wrote:Please do as it's driving me mad trying to understand how to program Eprom's.....................

;) ;) ;) ;) ;) ;) ;)
OK but the info will come in stages.

I know you are pretty clued up about modding radios wrt channel codes etc etc so I'll do a bare bones 'EPROM FILE' for an imaginary radio and see how much of it makes sense straight away.

It will take me a while to prepare it and I'm not going to write it all in one go so give me a bit of time to report back.

It will be worth it hopefully ;)
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Re: Converting my AR144 to cover 555

Post by Ashtec »

Thank you there RD....................
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Re: Converting my AR144 to cover 555

Post by RD250 »

OK I've typed up something but it's too big for a forum post.

Also, you need to tell me what data formats your EPROM programmer can accept.

eg can it support SREC files eg *.S19 as these are easy and fast to send to the EPROM programmer.
If you are not sure then maybe tell me which programmer you have.

Do you have any EPROMs? If so let me know which type you want to use.

Note that the tutorial I have written is very basic and it also assumes you will do EVERYTHING via the EPROM
eg LOW, MID, HIGH, HH, SPLITS, UK40FM all done via the EPROM so for a 148 the binary adders would be obsolete.

Hope this is what you are expecting.
Also, how do I get the tutorial to you?

The tutorial is embedded into the data file to create the EPROM so it contains a tutorial plus a sample bit of EPROM data for a block of 40 for a CB. It's all ready to test!

Each step is explained in a fairly minimal fashion so I hope it will be OK. But you should be able to create EPROMs fairly quickly :)

Note you also need to get some PC tools and I'd recommend you use the same ones as me to edit the data file/tutorial
and to assemble it to an SREC file.

Trust me, it's easy and the tools are old school command line so no learning whatsoever required :)

Someone else may be able to refine the tutorial and suggest better (more modern) tools to create the programmer the file but I do all my embedded programming on an old laptop so I'm happy to used stuff from the dark days of DOS :lol:
Last edited by RD250 on 12 May 2011, 22:58, edited 1 time in total.
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Re: Converting my AR144 to cover 555

Post by RD250 »

To give you a 'taste' of the bit you edit for each block it will look like this:

Note that the tutorial tells you what all this stuff means and where the numbers and the strange stuff like org 143 and fcb comes from.


Note that the forum text formatting has squashed it all to the left so it will look a bit less cramped in the correct editor.
But you can see this type of format is much more friendly to work with plus you can add your own comments anywhere if you follow a few basic rules.

The PLL code for channel 1 low band is 82 so you can see that this is entered below for channel 1.

Note also you are operating in a HEX free zone so no need to learn or use *ANY* HEX

The stuff below gets assembled into the HEX format by the assembler/compilerprogram for the programmer so you don't ever have to get dirty with an old school hex editor like in the EPROM data book :)

to use this you simply type

as1.exe myfile.asm

on a DOS command line so it's really easy to convert the file across for the programmer


;
; LOW Block Cobra 148 GTL-DX


; Raw channel changer code for channel 1 is 15

; Header wire to the EPROM to select LOW band is EPROM address line A7 (value = 128)
; so org header is (2^7) + 15 = 128 +15 = 143
; so the LOW block starts at EPROM address 143


org 143
fcb 82 ; Channel 1
fcb 83 ; Channel 2
fcb 84 ; Channel 3

fcb 85 ; this is a dummy location due to split

fcb 86 ; Channel 4
fcb 87 ; Channel 5
fcb 88 ; Channel 6
fcb 89 ; Channel 7

fcb 90 ; this is a dummy location due to split

fcb 91 ; Channel 8
fcb 92 ; Channel 9
fcb 93 ; Channel 10
fcb 94 ; Channel 11

fcb 95 ; this is a dummy location due to split

fcb 96 ; Channel 12
fcb 97 ; Channel 13
fcb 98 ; Channel 14
fcb 99 ; Channel 15

fcb 100 ; this is a dummy location due to split

fcb 101 ; Channel 16
fcb 102 ; Channel 17
fcb 103 ; Channel 18
fcb 104 ; Channel 19

fcb 105 ; this is a dummy location due to split

fcb 106 ; Channel 20

fcb 107 ; Channel 21
fcb 108 ; Channel 22

fcb 109 ; Channel 24 ; note that the channel hops wrt channel 23 have to be arranged like this
fcb 110 ; Channel 25 ; with the shifted sequence
fcb 111 ; Channel 23
fcb 112 ; Channel 26
fcb 113 ; Channel 27
fcb 114 ; Channel 28
fcb 115 ; Channel 29
fcb 116 ; Channel 30
fcb 117 ; Channel 31
fcb 118 ; Channel 32
fcb 119 ; Channel 33
fcb 120 ; Channel 34
fcb 121 ; Channel 35
fcb 122 ; Channel 36
fcb 123 ; Channel 37
fcb 124 ; Channel 38
fcb 125 ; Channel 39
fcb 126 ; Channel 40
Last edited by RD250 on 12 May 2011, 22:56, edited 2 times in total.
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Re: Converting my AR144 to cover 555

Post by RD250 »

The other bonus is that the file format from the assembler program is really efficient so you only program the parts of the EPROM that are needed

eg here's the SREC file contents for the stuff above. This is what goes to the EPROM programmer.

Don't try and make any sense of it, just look at how small it is and also be happy that you don't have to understand the hex codes.

I can understand the file format below because I've been programming stuff in hex for many years but it isn't important to know what the format below is. Your programmer should be fine with it.

If not I can find another format for the programmer file easily enough.
S123008F52535455565758595A5B5C5D5E5F606162636465666768696A6B6C6D6E6F70711D
S11000AF72737475767778797A7B7C7D7E28
S9030000FC
Last edited by RD250 on 12 May 2011, 22:57, edited 1 time in total.
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Re: Converting my AR144 to cover 555

Post by Ashtec »

Pm sent........................
RD250
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Re: Converting my AR144 to cover 555

Post by RD250 »

Hi Paul
I've got your email address and I'll send you some stuff shirtly.

I've pasted in some stuff from some old files of mine as well.

Note that I haven't played with EPROMs for CBs for maybe 20yrs so I hope I haven't made any errors with respect to the Cobra 148GTL-DX codes or pinouts below etc. :)

The tutorial assumes you want to design your own EPROM board rather than modify someone elses
although I can do an amended version if you want to buy a premade EPROM board with a specific EPROM already fitted and with specific connections to the EPROM etc.

The EPROM proposed in the tutorial is a 27C256 with 28 pins and below shows how it connects up

The stuff below is also in the tutorial I will send you shortly

I really should start a new thread about EPROMs so I'll try and do this later today :)


Note also that the forum formatting squashes all the text across to the left so it looks a bit untidy below but it looks better in the tutorial.

Also note that the connections to the MC145106 need to be level shifted to suit the 8V operation of the PLL chip because the EPROM only runs at 5V for logic levels.

Don't worry about this for now but there needs to be components added to the board to allow this voltage shift to be done correctly.

;;;;;;;;;;;;;;;;;;;;;;;; APPENDIX A;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;; 27C256 EPROM PINOUTS AND CONNECTIONS FOR A COBRA 148GTL-DX mk2 with 4008 binary adders removed.

;; ADDRESS Inputs

; A0 = pin 10 (from Channel Changer CC0. This originally added 1 channel when logic 1)
; A1 = pin 9 (from Channel Changer CC1. This originally added 2 channels when logic 1)
; A2 = pin 8 (from Channel Changer CC2. This originally added 4 channels when logic 1)
; A3 = pin 7 (from Channel Changer CC3. This originally added 8 channels when logic 1)
; A4 = pin 6 (from Channel Changer CC4. This originally added 16 channels when logic 1)
; A5 = pin 5 (from Channel Changer CC5. This originally added 32 channels when logic 1)

; A6 = pin 4 (LOW LOW band header wire connects here?)
; A7 = pin 3 (LOW band header wire connects here?)
; A8 = pin 25 (MID band header wire connects here?)
; A9 = pin 24 (HIGH band header wire connects here?)
; A10 = pin 21 (HIGH HIGH band header wire connects here?)
; A11 = pin 23 (UK40FM band header wire connects here?)
; A12 = pin 2 (free header connect to 0V GND if not used)
; A13 = pin 26 (free header connect to 0V GND if not used)
; A14 = pin 27 (SPLITS header wire connects here)


;; PLL code output (DATA) lines

; D0 = pin 11 connect to pin 17 on a MC145106 (adds 1 channel when logic 1)
; D1 = pin 12 connect to pin 16 on a MC145106 (adds 2 channels when logic 1)
; D2 = pin 13 connect to pin 15 on a MC145106 (adds 4 channels when logic 1)
; D3 = pin 15 connect to pin 14 on a MC145106 (adds 8 channels when logic 1)
; D4 = pin 16 connect to pin 13 on a MC145106 (adds 16 channels when logic 1)
; D5 = pin 17 connect to pin 12 on a MC145106 (adds 32 channels when logic 1)
; D6 = pin 18 connect to pin 11 on a MC145106 (adds 64 channels when logic 1)
; D7 = pin 19 connect to pin 10 on a MC145106 (adds 128 channels when logic 1)


; OTHER EPROM Pins

; /OE pin 22 (this should go to 0V GND on the EPROM board)
; /CE pin 20 (this should go to 0V GND on the EPROM board)
; Vss pin 14 (this should go to 0V GND on the EPROM board)

; Vcc pin 28 (This should go to +5V on the EPROM board)
; Vpp pin 1 (This should go to +5V on the EPROM board)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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Re: Converting my AR144 to cover 555

Post by 163TM847 »

I have a 2716 eprom here that was already programmed for the MC145106 [pulled from a MK2 148] that was LO.LO - HI +UK [The 4008's were also removed from the radio] How its fitted onto a board and wired up i have no idea, There was if i recall a bunch of diodes connected up on the back of the band switch though.

It should still be ok and If its any use to anyone they can have it.
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Re: Converting my AR144 to cover 555

Post by Ashtec »

Any info you have there RD will be helpful as im struggling i am looking to make my own eprom's.

For doing cb radio band 10 meter band's as this is what i do most of the time in radio mods.

If you are needing a drink for this info send my your AD and i will send some cash over as i was really thinking of looking for a few week course on this info as i can not move forward in moding radio's to the 10 meter bands with out to much work.

;) ;) ;) ;) ;) ;) ;) ;) ;) ;) ;)
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