New expansion - UPD858 SSB chassis

[dt307]

its a pc-893 dual conversion type thanks

[lbcomms]

Hmmm, make that "add a a third variation" to the list.

Looking at the schematic, it uses a 10.695 first IF with low side local oscillator (16 MHz). The other two (i.e. Cobra 140 [single conversion] and 148 [dual]) common down here use a 7.8 MHz IF and a high side local oscillator in the 34 MHz region.

Also, it appears to only use dual conversion on FM, with AM being single conversion like the AR-144.

I'm only having an educated guess from a schematic as we don't have one of those radios here, can you please confirm the following:

Channel 20, mid block VCO frequencies:

AM = 16.5100 MHz
FM = 16.5100 MHz
USB = 16.5125 MHz
LSB = 16.5075 MHz

On receive (clarifier centred), and Tx (clarifier centred if it has a slider mod). The test point to measure this from will likely be a bared resistor near the Tx mixer stage.

Once it's confirmed I'll make a firmware to suit, but I'll need you to try it out and let us know the result here.

Thanks!

[cb4ever104]

Once it's confirmed

Service manual is here Sue .

http://www.cbradio.nl/president/Service ... er_ENG.pdf

Sammy

[lbcomms]

Thanks - we had a similar one, but every bit of info helps. The block diagram in both has an error - it shows the 15MHz downmix signal mixing with the 10.695 IF to give the second IF of 0.455 MHz, hmmm, 15 - 10 is not 0.5 or anywhere near it

The schematic is correct, 10.696 - 10.240 (from pin 8 of the PLL) = 0.455

Don't know if there are any other mistakes in there, so a measurement / confirmation of the math will increase the chances of it working first time...

[dt307]

no probs will get onto it asap

[dt307]

soz had to get a bla350 off the bench with blown fets


all checks out as per service manual and as you quoted on ch 20 mid

[dt307]

question .....i can burn hex files direct to the 328p with the uno (i tried yesterday and went easy enough) or you rather me use the programmer you listed.
as thats what i been trying to learn with.
the way i was doing it was i started with the uno got a working vfo sketch with a small oled to replace the channel led but was a basic vfo to replace the mixing xtal,when i was happy i uploaded it to a nano which i could still debug easy and the final design was going to be a micro.
i put it all on stop after talking with you as your ideas are way better and you actually know what your doing rather than me just making changes to some 1 else sketch.
what your doing is perfect for what i need adding bands ect and be nice in the future is the source code is given so i could may be work on adding different screens lcd/2line/oled depending on the task at hand ......your doing great work Sue and thank you for taking the time to do and share this

[dt307]

hi Sue ...was just wondering why the board is isolated then bridged over? a0/a1/a2 what have i missed ...thanks

[lbcomms]

all checks out as per service manual and as you quoted on ch 20 mid

Thanks for that!

[lbcomms]

just wondering why the board is isolated then bridged over? a0/a1/a2

Not sure what you mean by "isolated" - A0 A1 ans A2 are just analog or Port C inputs, A0 was not needed so was just grounded to make the board layout easier. It gives a convenient ground for the VRef bypass capacitor and for the voltage dividers from the SSB mode inputs. A1 / A2 are just configured as regular digital inputs and the resistors divide the 9V on the mode switch LSB / USB selector pins by 2, i.e. to 4.5 volts.

There are steering diodes inside the micro so the ground side resistors are nor strictly essential, but I'd rather not rely on just the diodes for the sake of saving two resistors...

[lbcomms]

can burn hex files direct to the 328p with the uno (i tried yesterday and went easy enough) or you rather me use the programmer you listed

Use whatever works for you, even the old STK100 programmer will work if you have a parallel port and XP on your computer

That suggestion was written for someone with no or little experience with AVRs, as long as your programmer talks to SCK, MISO, and MOSI it'll be fine.

The UNO will also be OK to use instead of the Nano, but it might be a tight fit into a mobile radio.

got a working vfo sketch with a small oled to replace the channel led but was a basic vfo to replace the mixing xtal,

If the output of your signal source replaces the downmix crystal, the micro won't know what channel the radio is on, only what band (lo, mid, high etc) is active, and therefore won't be able to drive a channel indicator. To control the LED, the micro will need to know the state of the PLL programming pins (i.e. another 7 inputs needed). We didn't go that way as it would have meant hacking the radios channel display in a way that couldn't be easily reversed.

One thing on the "ideas to do later" list is to have an I2C port expander read the channel switch and control an I2C LED or LCD display mounted in a small box that sits on top of the radio. Only 4 wires needed to connect the box (12V, ground, SCL, SDA) and no additional micro I/O needed.
The box would then display, selectable with a switch, either channel number or frequency (or both at the same time if a 16x2 LCD is used) and would be easily reversible.

be nice in the future is the source code is given so i could may be work on adding different screens

While we are getting the hardware and PC app working it's been written in Imagecraft Pro and uses a commercial USB lib - so the source at the moment won't be much good unless you have those. We did it that way so we could recycle a lot of existing code.

Once it's all up and running we'll rewrite it either as an Arduino sketch or a shareware compiler such as WinAVR or Bascom, and open source it. Can't see there will be a huge market for this application so not looking to make anything out of it.

There's nothing tricky or special going on, just reading analog and digital inputs then sending a number to a prewritten lib to control the SiLabs IC, so a rewrite to a sketch should be pretty straightforward...

[dt307]

thanks for the detailed reply all understood.
inc is the pic of the cut and the 3 bridges over the cut i was trying to say

sue.jpg

yes the sketch i used had an encoder, the radio was locked on 1 channel (ch 2 on a unidenn as its binary 16 and easy to do) and the dds was fed into the cap in series with the mixer xtal and vco but the cap was lifted on the xtal side ....was just messing about

[lbcomms]

Ahh, understood now, forgot about that one. It was a recycled piece of board with a few traces already cut that needed to be "uncut" for this one.

We also tried something similar on a radio with an LC7131 PLL (no downmixing, clarifier and SSB offsets all done at the 10.24 input). The PLL hard wired onto one channel and having the micro do the math and generate a frequency near 10.24 for each channel, feeding it into the PLL, making it possible to add low / high bands and 5K/10K offsets.

[dt307]

Ahh, understood now, forgot about that one. It was a recycled piece of board with a few traces already cut that needed to be "uncut" for this one.

We also tried something similar on a radio with an LC7131 PLL (no downmixing, clarifier and SSB offsets all done at the 10.24 input). The PLL hard wired onto one channel and having the micro do the math and generate a frequency near 10.24 for each channel, feeding it into the PLL, making it possible to add low / high bands and 5K/10K offsets.

yer i just followed it blindly and prep the pcb then when i went to solder it up and looked at the diagram and didnt make sense.thought it may have been a 1 board fits all type of affair....no dramas

[dt307]

hi Sue just to confirm i had the email for the 858 with thanks ...i will wait when ever you get time for the 8719 version as i dont have an 858 to hand atm to try it on ...thanks