There's not a lot of info on the 'net about these.
OK so it's a Plessey "Smalltalk" VHF Manportable with 16kbps speech crypto. One would think there would be a processor in there but nope, CMOS only. And not a lot of that, for what it does. Date codes are mostly 1984.
30-76 MHz is 1840 x 25 kHz. So channels 800 to 960 will fall in the 6m Amateur Radio band,
At this stage I know almost nothing about these radios. I don't even know what the IF freqency is. Or how the channels work. I'm guessing as to the functions of the various boards... Reverse Engineering in progress.
Batteries are AG10 / LR1130 A.K.A.
Front view. Note how eager I was to get started with the reverse engineering, the top of the knobs come off exposing the screw to loosen them.
The pipe clamp around the antenna connector is because there's a switch that disables things when the antenna is not screwed in. And the radio didn't come with an antenna -- it came with a pipe clamp.
419/1/73392 Serial Number 843Z
| SO41P | FM IF Amplifier with Demodulator |
| TBA820 | Audio Amplifier |
| LM307H | Op-Amp |
| CA3078 | Op-Amp |
| 4051 x2 | 8-channel analog multiplexer/demultiplexer |
| 4066 x2 | Quad analog switch |
| Cathodeon Crystal Filter Type BP 4643-00 |
Cathodeon Crystals started off as a division of Pye, and radios like this one (with only one crystal for 1840 channels) helped put them out of business.
419/MB/73393 SH.2 ISS.3
419/1/72478 Serial Number 0843Z
419/MB/72479
| 4008 x3 | 4-bit binary full adder |
| 4011 | Quad 2-input NAND gate |
| 4013 | Dual D-type flip-flop |
| 4040 | 12-stage binary ripple counter |
| 4059 | Programmable divide-by-N counter |
| 4069 | Hex inverter |
| 4070 | Quad 2-input XOR gate |
| 4072 | Dual 4-input OR gate |
| 4081 | Quad 2-input AND gate |
| SP8655A | 200MHz divide-by-32 prescaler |
| SL622C | AF Amplifier, VOGAD & Sidetone Amplifier |
| CA741 | Op-Amp |
| CA3078 | Op-Amp |
| CA3130 | Op-Amp |
4059 Mode
419/MB/70016 SH.1 ISS.2
| 4001 | Quad 2-input NOR gate |
| 4011 | Quad 2-input NAND gate |
| 4017 | Decade counter with 10 decoded outputs |
| 4027 x2 | Dual J-K master-slave flip-flop |
| 4029 | Presettable up/down counter, binary or BCD-decade |
| 4042 x4 | Quad D-type latch |
| 4049 x2 | Hex inverter |
| 4069 | Hex inverter |
| 4073 | Triple 3-input AND gate |
| 4081 | Quad 2-input AND gate |
| 4093 | Quad 2-input NAND gate, schmitt trigger inputs |
| 4175 | Quad D-type flip-flop |
| 4502 | Hex inverting buffer (tri-state) |
| 4519 | Quad 2-input multiplexer |
| 4520 | Dual 4-bit binary up counter |
| 4555 | Dual 1-of-4 decoder/demultiplexer |
| 4585 | 4-bit digital comparator |
| 74C89 x2 | 64-bit (16 x 4) RAM |
OK, so this board has 16 bytes of CMOS RAM.
419/1/70013 (?) Serial Number 0843Z 419/MB/70016 SH.2 ISS.3
419/1/70007 Serial Number 0842Z
DV1210S, 10W N-Channel 175MHz FET
ISS.3
The break in the trace looks like the PCB was manufactured like that?
The front panel PCB has
| 4511 | BCD to 7-segment latch/decoder/driver |
| 4529 | Dual 4-channel analog data selector/multiplexer |
I numbered the flex PCB traces from the top, 1-25, as a handle for reverse engineering the schematic.
The backplane is 4 x DIN41612 AB (Type B)
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