UPD858C versus Uniden D858 PLL

[Night Ranger]

Does anyone know if there are any compatibility issues between the UPD858c PLL chip and the Uniden D858 PLL chip? I have a Midland 13-883b 23 channel CB with the UPD858C chip that has gone bad. The lock detect pin is high and the VCO is free running. Changing the channel selector only changes the PD output on some channels and the output is not what you would expect. I checked the voltage on the programming pins and the BCD input from the channel selector matches the truth chart in the Sams photofact. I found one dealer in the United Kingdom that has a upd858c in stock and one Ebay dealer with the Uniden D858. Can these two chips be used interchangeably?

Thanks,

Night Ranger

[Sandbagger]

Dec 25, 2013 12:53:42 GMT -5 Night Ranger said:

Does anyone know if there are any compatibility issues between the UPD858c PLL chip and the Uniden D858 PLL chip? I have a Midland 13-883b 23 channel CB with the UPD858C chip that has gone bad. The lock detect pin is high and the VCO is free running. Changing the channel selector only changes the PD output on some channels and the output is not what you would expect. I checked the voltage on the programming pins and the BCD input from the channel selector matches the truth chart in the Sams photofact. I found one dealer in the United Kingdom that has a upd858c in stock and one Ebay dealer with the Uniden D858. Can these two chips be used interchangeably?

Thanks,

Night Ranger

First up, you have to consider that the PLL chip itself is not the "bad"part. Make sure all of your PLL mixer oscillators are working. Also, is the VCO voltage out of the chip locked high (5V) or low? Can you adjust the VCO and cause the error voltage to swing the other way? Can you see the frequency and level of the programmable divider input? I've seen issues with the UHIC-001 oscillator block (replacing it with a UHIC-003 will give you more range). Some 858 PLL radios also have a 4011 interface wired as a quad inverter, which goes in between the PLL VCO drive and also the PG divider input, so that's another area to consider.
Also, you have to consider that some knucklehead tried to add extra channels to it, and goofed up the programming pins and the VCO tuning. It's not hard to do if you don't know what you're doing.

But to answer your question, I've only ever seen the 858c chip, as made by Uniden. I don't know if a generic "858" will sub directly. And if you go that route and there's another problem in the PLL, you won't know if the problem is an incompatible chip or an issue somewhere else.

[Night Ranger]

Dec 26, 2013 11:16:50 GMT -5 Sandbagger said:

Dec 25, 2013 12:53:42 GMT -5 Night Ranger said:

Does anyone know if there are any compatibility issues between the UPD858c PLL chip and the Uniden D858 PLL chip? I have a Midland 13-883b 23 channel CB with the UPD858C chip that has gone bad. The lock detect pin is high and the VCO is free running. Changing the channel selector only changes the PD output on some channels and the output is not what you would expect. I checked the voltage on the programming pins and the BCD input from the channel selector matches the truth chart in the Sams photofact. I found one dealer in the United Kingdom that has a upd858c in stock and one Ebay dealer with the Uniden D858. Can these two chips be used interchangeably?

Thanks,

Night Ranger

First up, you have to consider that the PLL chip itself is not the "bad"part. Make sure all of your PLL mixer oscillators are working. Also, is the VCO voltage out of the chip locked high (5V) or low? Can you adjust the VCO and cause the error voltage to swing the other way? Can you see the frequency and level of the programmable divider input? I've seen issues with the UHIC-001 oscillator block (replacing it with a UHIC-003 will give you more range). Some 858 PLL radios also have a 4011 interface wired as a quad inverter, which goes in between the PLL VCO drive and also the PG divider input, so that's another area to consider.
Also, you have to consider that some knucklehead tried to add extra channels to it, and goofed up the programming pins and the VCO tuning. It's not hard to do if you don't know what you're doing.

But to answer your question, I've only ever seen the 858c chip, as made by Uniden. I don't know if a generic "858" will sub directly. And if you go that route and there's another problem in the PLL, you won't know if the problem is an incompatible chip or an issue somewhere else.

I'm pretty sure the UPD858c chip is bad. Normally the PD (phase detector) output pin on a PLL chip that goes to the VCO is a stepped voltage that increases or decreases voltage in a predictable manner as you change the channel selector from 1 to 23 or 40. For most of the channel selector settings their is no voltage output on the PD pin even though the voltage on the BCD programming pins is correct. One a few channels (about five channels) the PD output does put out voltage, but it does not increment/decrement in predictable steps like a normal PLL chip output voltage would do. I did measure the voltage after it passed through the AI/AO (Active In/Active Out) filter to smooth out the spikes. This radio was working correctly when I first got it, but the next time I turned it on several months later it would not receive or transmit. Also the VCO is free roaming at the bottom of it's range (16 MHz), and according to the truth chart it is suppose to be in the low 17 Mhz range. The reference oscillator is working and on frequency.

My initial question may be a moot point now. Apparently RFParts.com was updating their website over the holidays. When I searched their website a few days ago it would not list any entries for either the PLL02a or the UPD858. Now it has listings for both chips, so I can get the UPD858 chip from them now.

Night Ranger

[Sandbagger]

Dec 27, 2013 3:40:49 GMT -5 Night Ranger said:

Dec 26, 2013 11:16:50 GMT -5 Sandbagger said:

First up, you have to consider that the PLL chip itself is not the "bad"part. Make sure all of your PLL mixer oscillators are working. Also, is the VCO voltage out of the chip locked high (5V) or low? Can you adjust the VCO and cause the error voltage to swing the other way? Can you see the frequency and level of the programmable divider input? I've seen issues with the UHIC-001 oscillator block (replacing it with a UHIC-003 will give you more range). Some 858 PLL radios also have a 4011 interface wired as a quad inverter, which goes in between the PLL VCO drive and also the PG divider input, so that's another area to consider.
Also, you have to consider that some knucklehead tried to add extra channels to it, and goofed up the programming pins and the VCO tuning. It's not hard to do if you don't know what you're doing.

But to answer your question, I've only ever seen the 858c chip, as made by Uniden. I don't know if a generic "858" will sub directly. And if you go that route and there's another problem in the PLL, you won't know if the problem is an incompatible chip or an issue somewhere else.

I'm pretty sure the UPD858c chip is bad. Normally the PD (phase detector) output pin on a PLL chip that goes to the VCO is a stepped voltage that increases or decreases voltage in a predictable manner as you change the channel selector from 1 to 23 or 40. For most of the channel selector settings their is no voltage output on the PD pin even though the voltage on the BCD programming pins is correct. One a few channels (about five channels) the PD output does put out voltage, but it does not increment/decrement in predictable steps like a normal PLL chip output voltage would do. I did measure the voltage after it passed through the AI/AO (Active In/Active Out) filter to smooth out the spikes. This radio was working correctly when I first got it, but the next time I turned it on several months later it would not receive or transmit. Also the VCO is free roaming at the bottom of it's range (16 MHz), and according to the truth chart it is suppose to be in the low 17 Mhz range. The reference oscillator is working and on frequency.

My initial question may be a moot point now. Apparently RFParts.com was updating their website over the holidays. When I searched their website a few days ago it would not list any entries for either the PLL02a or the UPD858. Now it has listings for both chips, so I can get the UPD858 chip from them now.

Night Ranger

Good luck with the chip replacement. Hopefully that will cure it. If not we can revisit the other potential issues later.

[Night Ranger]

I have another radio that is making me scratch my head. I'll post a new thread called "Krazy Ken's TRC-451".

Night Ranger