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O2A MODS?
- Thread starter wldls1
- Start date
Heya again,
I can't seem to find this radio in my files...is this an AM or AM/SSB model? That will help me give you info on modifying the PLL for extra channels, etc. since the AM 02A boards give different frequencies than the SSB boards. Let me know, and I'll get you some mod info.
-Exit
I can't seem to find this radio in my files...is this an AM or AM/SSB model? That will help me give you info on modifying the PLL for extra channels, etc. since the AM 02A boards give different frequencies than the SSB boards. Let me know, and I'll get you some mod info.
-Exit
Although , if it's the lower channels you want ? I find the one wire from the switch to go to pin 9 of PLL and not 8 as they have in this pic. All other mod's seem to work just fine. Good luck to you.
Here is how you get upper channels on an 02A AM/SSB board. They produce different frequencies than the 02A AM only boards.
Cut the traces on both pins 10 and 11 on the PLL chip. Solder a 3.3k resistor across the traces where you just cut on each pin (bands on the resisitors are orange, orange, red for the first three bands). You can copy the illustration that Switch Kit provided, just cut the trace and solder a resistor in the same way on pin 10 as you do on pin 11. Take a DPDT center off toggle switch, put a wire from both the center poles on the switch to pin 8. Put a wire from the Pin side of pin 10 of the PLL to one end pole of the switch, and put another wire from the pin side of pin 11 on the PLL to the opposite pole of the switch. Diagram shown below.
0--0|-------> to Pin 10
0--0|-------> to Pin 8
0--0|-------> to Pin 11
Channels 12-27 will get you 27.425 to 27.595 when you tie pin 11 LOW (connects pin 11 to pin 8).
Channels 1-40 will get you 27.605 to 28.045 when you tie pin 10 LOW (connects pin 10 to pin 8).
You could probably get the lowers by tying pins 10 and/or 11 HIGH (connecting pins 10 or 11 to pin 9) per Switch Kit's description, but I have not messed with it on the AM/SSB boards, since I seldom go below channel 1 anyhow.
However, the VCO circuit on the 02A boards (both AM and AM/SSB) are rather narrow-banded, and only have a range of about 70 channels or so before you lose receive and transmit integrity. You CAN modify the VCO circuit, but it's not the easiest thing to do. Unless you really need to get the lowers, it's really not worth messing with. I'd just have the uppers and call it good.
Power and modulation tweaks: AM Power (deadkey) VR4, SSB power: RV11/RV2, Modulation, remove Q37 and Q38. (Normally, I am NOT a fan removing modulation limiting devices, like transistors, diodes, etc., as they can distort SSB badly. However on the 02A AM/SSB chassis, removing them doesn't seem to affect the audio quality in a negative manner.)
Let me look up the clarifier mod, and I'll post that when I find it in my notes.
-Exit
Cut the traces on both pins 10 and 11 on the PLL chip. Solder a 3.3k resistor across the traces where you just cut on each pin (bands on the resisitors are orange, orange, red for the first three bands). You can copy the illustration that Switch Kit provided, just cut the trace and solder a resistor in the same way on pin 10 as you do on pin 11. Take a DPDT center off toggle switch, put a wire from both the center poles on the switch to pin 8. Put a wire from the Pin side of pin 10 of the PLL to one end pole of the switch, and put another wire from the pin side of pin 11 on the PLL to the opposite pole of the switch. Diagram shown below.
0--0|-------> to Pin 10
0--0|-------> to Pin 8
0--0|-------> to Pin 11
Channels 12-27 will get you 27.425 to 27.595 when you tie pin 11 LOW (connects pin 11 to pin 8).
Channels 1-40 will get you 27.605 to 28.045 when you tie pin 10 LOW (connects pin 10 to pin 8).
You could probably get the lowers by tying pins 10 and/or 11 HIGH (connecting pins 10 or 11 to pin 9) per Switch Kit's description, but I have not messed with it on the AM/SSB boards, since I seldom go below channel 1 anyhow.
However, the VCO circuit on the 02A boards (both AM and AM/SSB) are rather narrow-banded, and only have a range of about 70 channels or so before you lose receive and transmit integrity. You CAN modify the VCO circuit, but it's not the easiest thing to do. Unless you really need to get the lowers, it's really not worth messing with. I'd just have the uppers and call it good.
Power and modulation tweaks: AM Power (deadkey) VR4, SSB power: RV11/RV2, Modulation, remove Q37 and Q38. (Normally, I am NOT a fan removing modulation limiting devices, like transistors, diodes, etc., as they can distort SSB badly. However on the 02A AM/SSB chassis, removing them doesn't seem to affect the audio quality in a negative manner.)
Let me look up the clarifier mod, and I'll post that when I find it in my notes.
-Exit
this is a wierd radio. i cut track at pin 10. put a 3.3k across and the radio goes back to normal. conect 1 wire to pin 10and 1 to earth and nothing happens. now if i take the 3.3k out and conect 1 wire to one side of the cut track and conect the other wire to the other side of the track i get ch 28 to 59 with a couple missing..
if i do the same to pin 9 i get 27.605 up to 28.045 but only transmits to ch 70. it seems i dont have to earth or put in resistors. very strange.
hey thanks for all your help guys. im very grateful.
if i do the same to pin 9 i get 27.605 up to 28.045 but only transmits to ch 70. it seems i dont have to earth or put in resistors. very strange.
hey thanks for all your help guys. im very grateful.
I have always been a fan of the o2a cybernet boarded radios , especially the first run 40 channel radios. I still say one of the best audio sounding radios I've ever heard to this day on there own stock mic's. They also all had fantastic receive ! (rejection could be another issue) but all in all , I thought they were good decent radios.
The pll can be tricky (or so it would seem) many books and Internet instructions sometimes never seemed to add up ? but many times close , but I think on many occasions "they" are referring to certain radios that they never seem to mention ? I've only had the pleasure to go through one AM/SSB cybernet 02A board , most of all the rest were AM only radios , and I've never felt the need to add the uppers on those beings that they are used for SSB for the most part where the lowers tend to be more suited (used) for the AM'er in mind.
Over the years , I've had a lot of the AM only anolog type Midlands , everyone who's ever bought one from me was very very pleased with them , as I said , you can't beat the telephone quality audio they put out on there own stock mic's and the receive is only next to a damned receive amp , just great receive on those !
Is there any chance you could place a picture of this radio W1 ? thanks .......is this your radio ?
Hmm....
It was pin 9 and pin 10, instead of pin 10 and pin 11. That would be my fault, and I am sorry for misleading information. I was up a bit late last night, trying to dig through my file cabinet for mod info...
But what is interesting is that tying pin 9 or pin 10 to ground doesn't work... are you soldering the wire on pins 9 and 10 right on the pin itself, after you have installed the resistor? Perhaps this board is slightly different than the usual 02A AM/SSB board. Is there a way that you could locate the board number and post what it is? That might help me out.
Here's exactly what I had written down in my files.
[SIZE=+1]Coverage between 27.285-27.595 on channels 1-27 (+32 channels, channel 12 is 27.425)[/SIZE]
[SIZE=+1]1)Cut the Trace going to PIN #10. [/SIZE]
[SIZE=+1]2)Solder a 3.3 K resistor across the cut. [/SIZE]
[SIZE=+1]3)Solder the common pin of a SPST switch to ground. [/SIZE]
[SIZE=+1]4)Solder one of the other pins of the switch directly to pin 10. [/SIZE]
[SIZE=+1]With the switch on (connecting pin 10 to ground) the mod is activated.[/SIZE]
[SIZE=+1]Coverage between 27.605-28.045 on channels 1-40 (+64 channels)[/SIZE]
[SIZE=+1]1)Cut the Trace going to PIN #9. [/SIZE]
[SIZE=+1]2)Solder a 3.3 K resistor across the cut. [/SIZE]
[SIZE=+1]3)Solder the common pin of a SPST switch to ground. [/SIZE]
[SIZE=+1]4)Solder one of the other pins of the switch directly to pin 9.[/SIZE]
[SIZE=+1]With the switch on (connecting pin 9 to ground) the mod is activated.[/SIZE]
-Exit
It was pin 9 and pin 10, instead of pin 10 and pin 11. That would be my fault, and I am sorry for misleading information. I was up a bit late last night, trying to dig through my file cabinet for mod info...
But what is interesting is that tying pin 9 or pin 10 to ground doesn't work... are you soldering the wire on pins 9 and 10 right on the pin itself, after you have installed the resistor? Perhaps this board is slightly different than the usual 02A AM/SSB board. Is there a way that you could locate the board number and post what it is? That might help me out.
Here's exactly what I had written down in my files.
[SIZE=+1]Coverage between 27.285-27.595 on channels 1-27 (+32 channels, channel 12 is 27.425)[/SIZE]
[SIZE=+1]1)Cut the Trace going to PIN #10. [/SIZE]
[SIZE=+1]2)Solder a 3.3 K resistor across the cut. [/SIZE]
[SIZE=+1]3)Solder the common pin of a SPST switch to ground. [/SIZE]
[SIZE=+1]4)Solder one of the other pins of the switch directly to pin 10. [/SIZE]
[SIZE=+1]With the switch on (connecting pin 10 to ground) the mod is activated.[/SIZE]
[SIZE=+1]Coverage between 27.605-28.045 on channels 1-40 (+64 channels)[/SIZE]
[SIZE=+1]1)Cut the Trace going to PIN #9. [/SIZE]
[SIZE=+1]2)Solder a 3.3 K resistor across the cut. [/SIZE]
[SIZE=+1]3)Solder the common pin of a SPST switch to ground. [/SIZE]
[SIZE=+1]4)Solder one of the other pins of the switch directly to pin 9.[/SIZE]
[SIZE=+1]With the switch on (connecting pin 9 to ground) the mod is activated.[/SIZE]
-Exit
tis is exactly what i get but i dont need resistors and i dont run wire to ground.
the radio has a crystal filter that says 10.6935?
the board has TP-S30-MB on it?
will try and get some pics up.
thanks.
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