|Posted on Wednesday, July 30, 2003 - 9:34 pm: ||
I just installed a UPD2816 chip in my base and I cant seem to get it to work right. When you first turn it on it recieves fine for about 5 seconds then it goes dead....Still lit up and everything but no RX or TX. It does have TX for a couple seconds if you turn it on and Key it right away. But then it goes dead. I have checked for possible solder bridges and have found none. Any Ideas on where to start?
|Posted on Thursday, July 31, 2003 - 3:19 am: ||
Check if vco is going out of lock?
|Posted on Thursday, July 31, 2003 - 9:38 am: ||
Pin 15 is the lock detector , should be "high" (using a scope and NOT a DMM) if the VCO is locked. If it is not , check using a scope to make sure the 10.240 reference crystal is operating. Also Pin 9 , using a DMM should read "high" on RX and "low" on TX.
|Posted on Saturday, August 02, 2003 - 10:13 pm: ||
I thought those came with a upd2824 chip,like the pc122,not sure,thought 2816 was used in 146gtl?
|Posted on Sunday, August 10, 2003 - 8:24 pm: ||
You are right BigBob....I put the 2816 chip in to expand the channels. however I couldnt get it to work so I put the 2824 back in. Now I cant get the clarifier to slide more than 4Kc. Even with a 100Uh choke inline....Any suggestions?
|Posted on Monday, August 11, 2003 - 11:50 am: ||
Lift the ground side of D23 and install a 5.6µh choke from the open lead of the diode to ground.
With a volt meter find +8 volts on the clarifier control and cut that trace. Make sure nothing else is connected to this potentiometer contact.
Connect the open terminal of the clarifier control to + 8 volts constant (IC4 pin 1).
Jumper the other side of the clarifier control to ground.
Set the clarifier to the 3 O'clock position.
Connect a frequency counter to TP3.
In AM adjust L16 to 16.4900 MHz.
In USB adjust L17 to 16.4925 MHz.
In LSB adjust L18 to 16.4875 MHz.
~15mhz oscillator kit with xtal switching is a good deal for 40 up and down.
radio uses a 5mhz chip output to a tripler coil secondary only(primary not used)for upmixing. The unused primary is where the oscillator injection goes. ie cut pin 10 at pll to disconnect 5.12mhz chip output a switch is placed across this cut.15.360 is the standard reference for up mix.Xtals used in oscillator will be 15.800 for 40 up and 14.960 for 40 down. with a xtal switch to change between two. I can email a oscillator diagram pic if interested.Uses three 2sc710 and a few basic components. quite easy to make.
|Posted on Monday, August 11, 2003 - 4:08 pm: ||
Sorry mistake there. 14.960 should be 14.920 for 40ch down xtal.Clarifier knob can be refitted to 12.00 oclock position to give centre with more downslide.
|Posted on Monday, August 11, 2003 - 7:12 pm: ||
That would be great.....I will try it out anyway
|Posted on Monday, August 11, 2003 - 7:14 pm: ||
It's the same board as the pc122(early)got an expo kit for it had a tech install it been working 12 years,Adshar64's info is similar to or the same as the info in my cbcity tune up manual,good info.The expo kit is the same for 810e,pc122,cobra146gtl of course 12 years ago,and sorry I don't have the kit number,alot of help I am,lol.
|Posted on Monday, August 11, 2003 - 8:42 pm: ||
Yea I have a N expo kit but I couldnt get it to work either....I also tried a 100uh choke inline with D23 and it seemed to make it worse. I had 4kc before and only 2 with the choke inline....Maybe this thing wont make it down 5kc
|Posted on Monday, August 11, 2003 - 9:22 pm: ||
I'm not trying to discourage you by any means, but a buddy of mine in Florida had one of those base units. Nice and stable, but even after the local tech ordered and installed the expando kit, he could never get it to work.
I figure their has got to be a trick or something unique to those radios, but I don't know what. Seems the board is common enough, but just something is not the same????
Just letting you know that you are not the only one having difficulties with the 810 and extra channels. I bet with the help you are getting, you will figure it out. Good luck.
|Posted on Tuesday, August 12, 2003 - 5:41 am: ||
5.6 ~10 uf plenty
|Posted on Tuesday, August 12, 2003 - 3:37 pm: ||
Tuning the vco coil may be the answer to that problem re Alsworlds post.Was it a out of lock vco problem ? Also Buck you did not say the mod procedure you did to clarifier. If you know the varactor part check the voltage variation on it with a meter through the clarifier range. If you dont get 8v fully clockwise and 0 fully anticlockwise that is a problem. All volt drop components in series must be bypassed etc, as per above procedure. Putting too much inductance in series is no good with a standard varactor. Is the inductance on the anode side?
|Posted on Tuesday, August 12, 2003 - 5:45 pm: ||
I did the exact mod you posted....I think. will have to check tonight and get back to you. I will also check to see if I get 0-8v on my clarifier. Yea Al, I have had a heck of a time trying to get channels in this thing...Maybe someday
|Posted on Tuesday, August 12, 2003 - 10:26 pm: ||
don't give up. The tech I refered to is the same one I only let work on ONE of my radios. He was not the sharpest by any means, but he was fair in prices and did not rip people off.
You can do it, and the help from Adshar64 is more than this tech ever seemed to know about. Don't give up the faith.
I like those 810E's. Simple but rock solid radios. Get those extra channels and ROCK the airwaves!
|Posted on Wednesday, August 13, 2003 - 3:13 am: ||
This was the correct deal for chip changeover. Is this what you did?
Solder in a new PLL UPD2816.
Connect pin #20 to pin #21 GROUND.
Solder a wire from pin #9 to one side of a SPST switch.
Solder a wire from PCB GROUND to the other side of the switch.
If all goes well this should give you 27.420 - 27.860 Mhz.
channel will sit on zero's so you need 5kc at least on clarifier to get 5's again
8)If you can't get all the frequency coverage then adjust L-14 the VCO coil.
VR 10 is AM power
VR 6 is ALC
VR 5 is AM Modulation
VR 7 is RF Power meter
VR 1 is S-meter adjust
TX coils- L34, L35, L36 and L26
RX coils- L3 - L8, L10 and L11
|Posted on Wednesday, August 13, 2003 - 5:29 am: ||
There is 2 resistors in there that have to be replaced that effectively broadbands the vco,these radios are only 1.3 meg.wide the component change will bring that to 2 megs,I got the info around here somewhere I will e-fax you a copy this evening if I can find it,a cbc superexpo will do all thats nessesary to give you complete coverage 27.615-27.855 that's all you'll get from this board without investing alot of time and money.
|Posted on Friday, August 15, 2003 - 7:30 pm: ||
The Cobra 146GTL and Uniden PC- 122XL are low cost AM/S SB
radios using a gPD2824 PLL chip. The Uniden PC-122XL is the same radio as
the PC-122. They changed to the XL series when they went to the Cobra look
front panels. Uniden also made the PRO-810e, a base radio with the same
board as the 122. When this chassis initially came out there was no known
way to add extras. This was viewed as just another challenge for the CB
hackers and after a short while there were two methods of expanding
One uses two crystals that are switched into the tripler
coil and this yields 40 extras above and below the center off position is
regular 40, but it created a problem on sideband. This scheme rendered the
clarifier inoperative in the expanded positions. A wire from the clarifier
control to the expander kit was added to get some clarifier range but it was
limited and all three modes had three different center slots. These kits
also work on the Cobra 29-GTL and Uniden PC-76. These radios being AM only,
work fine and these kits are the preferred method of expansion.
The other kit doesn't use crystals. It uses two ICs that
generate a signal for the tripler coil in the PLL circuit. The clarifier
works the same in all positions of the expansion switch. This makes for ease
of operation. The only drawback is the total channel coverage is reduced. It
doesn't yield any lower frequencies but it does make the radio cover up to
Warning: The installation of the circuit board is easy. The leads should be as
short as possible. Locate the PC board as close to the 2824 PLL chip as
possible. Either a SPDT center of toggle switch or a three position rotary
switch can be used. If you buy a kit, it comes with the toggle switch
mounted to the PC board. It can be removed or used to secure the board and
switch in one step.
If you choose to build the PC board you can use a multipurpose PC board
such as Radio Shack #276-150 or #276-159. Position all the components as
close together as possible. Hand wire all connections using short wires.
Mount the board securely and be sure that nothing metallic comes in contact
with it including the speaker on bottom cover.
Once the PC board is installed and wired to the switch, four short wires
need to be connected to the PLL circuit. First run a wire from the
connection with the ground symbol on the expansion PC board to the can of
L15. Next connect the lifted side of C67 to the (OUT) connection of the
expansion board. Connect IC2 pin 10 to the expansion board connection marked
(IN). Then connect IC2 pin 11 to the expansion board connection marked (+5
To insure complete VCO coverage solder a 27pf capacitor across C72 on the
back side of the radio circuit board. Make sure to lay it down flat and keep
the leads short. Then double check your work looking for solder bridges and
CLICK ON PC
BOARD LAYOUT FOR MAGNIFIED VIEW.
CLICK ON This for chip layout .
Next is the alignment procedure. Connect a watt
meter, frequency counter and dummy load to the radio.
1) Put the radio in the AM mode on channel 1 with the expansion
switch in the normal position and transmit. You should read 26.965 on the
frequency counter. If the radio doesn't transmit, there may be a wiring
mistake somewhere or the VCO may need adjustment. Adding the capacitor
across C72 does change the adjustment slightly, but not usually enough to
loss channel 1. If everything looks OK then melt the wax in L38 and adjust
it slowly in either direction no more than 3/4 of a turn. You should now
transmit on channel 1.
2) Put the expansion switch in one of the upper channel
selections. and adjust L13 until you read either 27.285 or 27.605 on the
3) Put the expansion switch in the opposite expanded position and
you should read the other frequency listed above. You should read 27.285 in
one position and 27.605 in the other position. If not, tweak L13 a little
until you do.
4) Check to see that you still read 26.965 in the normal position.
5) Switch to the position that yields 27.605 and switch the
channel selector to channel 40. The counter should read 28.045. If it
doesn't, melt the wax in L38 and slowly adjust it until you read the 28.045
on your counter.
6) Go back to normal channel I and insure that you read 26.965 on
If everything went well you have a radio that goes up to 28.045. Of
coarse we know you will only receive these frequencies and never transmit
above 27.405. Remember 28.000 is the beginning of 10 Meters.
I'm told for the Ham operators out there, moving the wire on the expander
from pin 8 to pin 9 on the 7493 IC along with adjusting L13 and L38 will
give you coverage in the novice portion.
Well, this article was supplied for information purposes and I hope you
enjoyed it. Even if you don't tinker with radio equipment it's always good
to be aware of what's available.
|Posted on Monday, August 18, 2003 - 5:44 pm: ||
Adshar64... The IC change you posted was the exact one I did. I couldnt get the PLL locked. Actually I dont really need the extra channels but I would really like to slide down at least 5kc so I can chat with the locals. Bigbob sent me some info that I havent had time to study yet. Hopefully it will help me out.
|Posted on Monday, August 18, 2003 - 10:52 pm: ||
The trick is to bypass the diode and resistor in series with the varactor cathode once the basic mod is done. Check right on varactor leg with multimeter for 0 - 8v range with full clarifier range. If you dont get that look for a unessesary component causing a voltdrop in series.
|Posted on Sunday, August 24, 2003 - 10:41 pm: ||
anyone know the location of D-32 and IC-4???