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Uniden Washington Problems
- Thread starter deebeez
- Start date
congrats debeez.
the reason for the weird freq response in USB is probably due to the tuning of it's IF can.
that 7.8mhz IF can be really tricky to sample without loading down the circuit, but there is a trick you can use! (this will not be as 100% accurate as a properly calibrated piece of professional test equipment, but it will work about 98% as well)
just to make sure, check these items off before you do this:
1. is the VCO coil set to the proper voltage?
2. with the clarifier knob set to center position, are each of the VCO tuning cans (and variable cap for USB) showing their proper 34mhz signal?
3. you need to pull the wires off of TP7 and TP8 which are near the driver and final transistors. This is very important because you don't want much power coming out of the radio, just the signal.
ok, first step is to connect your freq counter to the center pin of the antenna jack with the ground going to the chassis.
next, confirm that you are still centered on the clarifier knob and haven't bumped it.
now load this video up on your phone or your computer if it is close to your bench:
this video contains 10 minutes of a continuous 1000hz tone.
Set the radio to channel 20, LSB mode, turn the mic gain all the way down, and key the mic while holding it up to either your phone or computer speaker.
play this video into the mic while keyed, and turn the mic gain up until you get a solid reading on your freq counter. in LSB mode, it should read 27.20400mhz.
if it does not, adjust CT2 until it does.
now go to USB mode, and do the exact same thing. now the freq counter should read 27.20600mhz. if it does not, adjust CT1 until it does.
now go to AM mode, and turn the mic gain all the way down. you can stop the video as you wont need it for AM mode.
with the mic gain all the way down, key the mic, and adjust L17 until your counter reads 27.20500mhz. (AM mode has a carrier so it doesn't need the steady tone in order to produce a solid signal on your counter)
27.20500 + 1000hz = 27.20600mhz for USB
27.20500 - 1000hz = 27.204000mhz for LSB.
you should be all set now.
LC
the reason for the weird freq response in USB is probably due to the tuning of it's IF can.
that 7.8mhz IF can be really tricky to sample without loading down the circuit, but there is a trick you can use! (this will not be as 100% accurate as a properly calibrated piece of professional test equipment, but it will work about 98% as well)
just to make sure, check these items off before you do this:
1. is the VCO coil set to the proper voltage?
2. with the clarifier knob set to center position, are each of the VCO tuning cans (and variable cap for USB) showing their proper 34mhz signal?
3. you need to pull the wires off of TP7 and TP8 which are near the driver and final transistors. This is very important because you don't want much power coming out of the radio, just the signal.
ok, first step is to connect your freq counter to the center pin of the antenna jack with the ground going to the chassis.
next, confirm that you are still centered on the clarifier knob and haven't bumped it.
now load this video up on your phone or your computer if it is close to your bench:
this video contains 10 minutes of a continuous 1000hz tone.
Set the radio to channel 20, LSB mode, turn the mic gain all the way down, and key the mic while holding it up to either your phone or computer speaker.
play this video into the mic while keyed, and turn the mic gain up until you get a solid reading on your freq counter. in LSB mode, it should read 27.20400mhz.
if it does not, adjust CT2 until it does.
now go to USB mode, and do the exact same thing. now the freq counter should read 27.20600mhz. if it does not, adjust CT1 until it does.
now go to AM mode, and turn the mic gain all the way down. you can stop the video as you wont need it for AM mode.
with the mic gain all the way down, key the mic, and adjust L17 until your counter reads 27.20500mhz. (AM mode has a carrier so it doesn't need the steady tone in order to produce a solid signal on your counter)
27.20500 + 1000hz = 27.20600mhz for USB
27.20500 - 1000hz = 27.204000mhz for LSB.
you should be all set now.
LC
Man LC, you have been helping a bunch of people lately!! Thanks much for all the help to others. Just reading through threads and see you have been a busy fella with helping fix others issues. And you have been the one to ask them if hey want the help!! Good deal man.
And again thx for being a help along with the rest of the crew. Don't want to leave anyone out. Not saying that anyone else isn't helping, been seeing a lot of it as of late, but you have been more active I guess you could say. And oh yeah, don't let the dip shits get at you about your other posting!! You know you're right, and the truth hurts sometimes.
Anyways, just thought I would give a big thx to you and all the others that help many with their radio issues. Much obliged. Good day. And to the poster, glad you were able to resolve the issue!! Some great guys around here, that is you just sit back and listen for a spell, you'll most likely get your answer to 99.9% of your issues with radios that is. Anyways, again, many thanks to all the gents that help with things like this. Keep up the great help.
73 and God Bless.
And again thx for being a help along with the rest of the crew.
Don't want to leave anyone out. Not saying that anyone else isn't helping, been seeing a lot of it as of late, but you have been more active I guess you could say. And oh yeah, don't let the dip shits get at you about your other posting!! You know you're right, and the truth hurts sometimes.Anyways, just thought I would give a big thx to you and all the others that help many with their radio issues. Much obliged. Good day. And to the poster, glad you were able to resolve the issue!! Some great guys around here, that is you just sit back and listen for a spell, you'll most likely get your answer to 99.9% of your issues with radios that is. Anyways, again, many thanks to all the gents that help with things like this. Keep up the great help.
73 and God Bless.
Thanks for the flowers DBFL. It's always great to hear that you are appreciated.
Not sure if it was like this for you, but when i started the hobby it was like everyone was keeping secrets from everyone else, and if you were new they wouldn't even tell you the phone number of the CB dealers so you could buy a new radio. This always bothered me and i swore i would never be one of those ops.
I guess it doesn't hurt that I am at work when i post on here 99% of the time.
My job requires me to stay put in front of a computer for long periods of time, but the actual work happens only at certain times.
I guess this is why some people get the impression that i spend all my time here. LOL.
take it easy and thanks again,
LC
Not sure if it was like this for you, but when i started the hobby it was like everyone was keeping secrets from everyone else, and if you were new they wouldn't even tell you the phone number of the CB dealers so you could buy a new radio. This always bothered me and i swore i would never be one of those ops.
I guess it doesn't hurt that I am at work when i post on here 99% of the time.
My job requires me to stay put in front of a computer for long periods of time, but the actual work happens only at certain times.
I guess this is why some people get the impression that i spend all my time here. LOL.
take it easy and thanks again,
LC
Thanks Buddy!
Hey where you been lately?
I finally got my sencore CB42 working! turns out i had a bad 1mhz crystal on the freq counter board.
good to see you around here.
LC
Hey where you been lately?
I finally got my sencore CB42 working! turns out i had a bad 1mhz crystal on the freq counter board.
good to see you around here.
LC
Just giving credit where credit is due bro.
Been around. Not a lot of time for forum postings these days. YouTube keeps me quite busy. I average about 75 to 150 emails, pm's a day bro. It is 11:46 pm here and just got finish uploading a new video on the B&K 2040 signal generator repair. Had PLL issues. Posted here on site.
Good to here you got that Sencore working. That is great. Seen that problem a few times.
Always a pleasure to chat with you LC.
RT
It would take an hour or two to go over the circuit diagram, however since this is a sideband radio you should have more than one means to adjust the frequency, beginning with the local oscillator that drives the MB 8719 PLL chip sometimes however there is no variable capacitor associated with this oscillator only fixed caps. For this radio the crystal should be running on 10.240 MHz.
CT1 and CT2 are used to adjust the upper and lower sideband BFO crystals. L17 is a part of the adjustment, and you will need a frequency counter for this. L19 and L20 appear to be a part of the BFO circuit and switched in by diode switches and hence I supect these two will be adjustable in terms of setting the BFO on frequency along with those previous variable caps. I am reading this as fast as I can to see whats up here. Actually I believe that L19 and L20 adjust crystal X4 which is 11.125 MHz to pull it a kilo hertzs or two up or down from 11.125 MHz.
Below is are links to the circuit diagram and the block diagram, the block diagram may help you out to understand the mixing scheme and get you to see what you might be missing in your adjustments that you are making.
http://www.cbtricks.com/.../uniden_washington_mb8719_sch.pdf
http://www.cbtricks.com/.../uniden_washington_mb8719...
LC you nailed it!! When I started messing with AM, there were a couple of trouble makers for sure!! Radio Rambos!! First radio was a cobra 19 and a mag mounted Wilson 5000 on a 1989 They always keyed on me and called me names and such. So I told them keep it up and I will make sure you don't talk. Guess they didn't beleive me and next thing you know I am running a 2pill pushing an 8 pill with 2 150AH DEKA Unigy 2 batteries in the rear of my jeep grand Cherokee 4 door. Placed antenna about 12" from back of truck in center and one of the local big boys that ran tube boxes helped me tune the antenna with an MFJ meter. He actually knew his stuff!! Running a 7-10kw suburban. Mount was Breedlove and antenna was the large single coil monkey made antenna that was about 8ft tall that I actually picked out at the storage facility here in Daytona Beach where MM antennas started. Man that setup for a 12vdc stock alternator setup rocked. At any rate I didn't get messed with much after that and the fact I found both of the sh** heads and they were both about 4'10" and frail as a potato chip LOL. Like I said after that they were like my best friends!! Funny how things work out.
This go around when I got back into the radio thing, I was traveling from FL to Michigan and just thought a little radio would help and it did. But when I returned home and got on SSB around my QTH, I was suprised at how many there were in the group of people locally to speak with. And man it became an addiction again LOL! One radio after another until I got the Icom 746 and kenwood ts140 within 2 days of each other, I was done shopping for a spell. The Icom 746 has been a workhorse and has never given me an issue since I have owned it. Dead on freq all the time, and has great audio with the stock HM-12 hand mic and proper settings of the compression and mic level. I love my CB's and even my exports, but once I went HF and saw the difference, I had to at least try. At any rate, my life story aside, I totally get the secret BS people would think they knew back in the day LOL!! If you weren't part of the "group", you didn't get any help or info!!
Anyways, like I said, time moved on, but the bs from back in the day still remains. What is funny is 99.9% of it is stuff that has already been done. Gotta love the ones that swear they re invented the wheel LOL!! Have a great day and keep at it man. You have helped many and I am sure you will help many more!! You're alright in my book! I'll say that, just reading and seeing what you do for others. There are a few others that are like you and they know who they are. You gents knowledge is the key to keeping things alive, so please keep up the great work and don't stop sharing good info man!!
73 and God Bless to you and yours.
Sean.
This go around when I got back into the radio thing, I was traveling from FL to Michigan and just thought a little radio would help and it did. But when I returned home and got on SSB around my QTH, I was suprised at how many there were in the group of people locally to speak with. And man it became an addiction again LOL! One radio after another until I got the Icom 746 and kenwood ts140 within 2 days of each other, I was done shopping for a spell. The Icom 746 has been a workhorse and has never given me an issue since I have owned it. Dead on freq all the time, and has great audio with the stock HM-12 hand mic and proper settings of the compression and mic level. I love my CB's and even my exports, but once I went HF and saw the difference, I had to at least try. At any rate, my life story aside, I totally get the secret BS people would think they knew back in the day LOL!! If you weren't part of the "group", you didn't get any help or info!!
Anyways, like I said, time moved on, but the bs from back in the day still remains. What is funny is 99.9% of it is stuff that has already been done. Gotta love the ones that swear they re invented the wheel LOL!! Have a great day and keep at it man. You have helped many and I am sure you will help many more!! You're alright in my book! I'll say that, just reading and seeing what you do for others. There are a few others that are like you and they know who they are. You gents knowledge is the key to keeping things alive, so please keep up the great work and don't stop sharing good info man!!
73 and God Bless to you and yours.
Sean.
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