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Post by Countryboy on Feb 25, 2013 17:25:56 GMT -5
I have been keeping track on the old Uniden/President Madison and Washington radios. Will get one at some point and would like some info on what do have done to it when I do. Would like to update it with all the stuff I can get in it like sliders and variable power switch and that sort of stuff. Not the noise toys though. Don't need that stuff.
Can anyone suggest the right stuff to get so I can talk with all these new radios that is out here nowdays. Don't really know that much about it. Just want to make it cool.
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Sandbagger
Administrator/The Boss 
Posts: 6,246 
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Post by Sandbagger on Feb 25, 2013 18:24:19 GMT -5
I have been keep track on the old Uniden/President Madison and Washington radios. Will get one at some point and would like some info on what do have done to it when I do. Would like to update it with all the stuff I can get in it like sliders and variable power switch and that sort of stuff. Not the noise toys though. Don't need that stuff. Can anyone suggest the right stuff to get so I can talk with all these new radios that is out here nowdays. Don't really know that much about it. Just want to make it cool. Well, if it's going to be your only radio, used on a daily basis, and you like to venture out of band, then adding extra channels would be a choice. Depending on which model radio (and which version, old or new) will determine exactly how this is accomplished. Personally, I would not go for increasing clarifier range beyond +/-5 khz. First off, it's a waste as you can jump channels in 10 Khz steps, and you only need the clarifier to cover the range "in-between". Secondly, and probably more important, is that extending "slide" range often makes the radio drift, which can be a royal pain when operating on SSB. On the other hand, if this is not your only radio, rather a "Sunday driver", situation, I'd leave it as close to stock as you could, and enjoy it as it was meant to be. As for power mods, DON'T, at least do not increase the power. If it were me, I'd drop the dead key down to 1.5 -2 watts and then buy a small amplifier and let the modulation really swing hard. Of course, anytime you pick up a 30+ year old radio, there may be things that need to be done (the 100,000 mile tuneup) to get it back to peak performance. But there isn't a new radio out there that does anything differently than the older ones, and those oldies can talk and hear just as well (and in some cases better) that a new radio. I guess it's like the difference between whether you'd rather tool around town in a brand new Corvette, or a fully restored 1960's vintage. They'll both get you from point A to point B, it then becomes a personal choice decision whether you prefer the latest flash, or the nostalgic appeal of yesterday. |
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Post by KneeBiter on Feb 25, 2013 18:36:08 GMT -5
I have a friend that has a Washington with the channels in it and the slider all set. He wants to sell it. If you are interested I will give you his email or private message me with your email and I will have him email you. I know him well and he is an honest guy. The radio is in nice condition. If you buy a different one with no mods done you can get all the mods online. If you are ok with a soldering iron and take your time you can do the mods yourself.
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Post by cbrown on Feb 26, 2013 9:38:07 GMT -5
If it were me and I was planning on modding a President/Uniden chassis, I'd probably go for the Weakstation mod.
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Post by Countryboy on Mar 5, 2013 14:52:33 GMT -5
Well knee, I mostly think good enough needs to stay left alone. I mean I think the old way was good back then so it is good enough now. I hat the new Walmart world we live in. They came to town and all the other shops went out of business and life went down hill. I hate it. And by the way, I have found a Washington with the 858 chip I am thinking about getting. Hope I can turn it into what I am looking for.
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bigt
Mudduck
Posts: 38
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Post by bigt on Feb 7, 2015 10:13:26 GMT -5
I have been keep track on the old Uniden/President Madison and Washington radios. Will get one at some point and would like some info on what do have done to it when I do. Would like to update it with all the stuff I can get in it like sliders and variable power switch and that sort of stuff. Not the noise toys though. Don't need that stuff. Can anyone suggest the right stuff to get so I can talk with all these new radios that is out here nowdays. Don't really know that much about it. Just want to make it cool. Well, if it's going to be your only radio, used on a daily basis, and you like to venture out of band, then adding extra channels would be a choice. Depending on which model radio (and which version, old or new) will determine exactly how this is accomplished. Personally, I would not go for increasing clarifier range beyond +/-5 khz. First off, it's a waste as you can jump channels in 10 Khz steps, and you only need the clarifier to cover the range "in-between". Secondly, and probably more important, is that extending "slide" range often makes the radio drift, which can be a royal pain when operating on SSB. On the other hand, if this is not your only radio, rather a "Sunday driver", situation, I'd leave it as close to stock as you could, and enjoy it as it was meant to be. As for power mods, DON'T, at least do not increase the power. If it were me, I'd drop the dead key down to 1.5 -2 watts and then buy a small amplifier and let the modulation really swing hard. Of course, anytime you pick up a 30+ year old radio, there may be things that need to be done (the 100,000 mile tuneup) to get it back to peak performance. But there isn't a new radio out there that does anything differently than the older ones, and those oldies can talk and hear just as well (and in some cases better) that a new radio. I guess it's like the difference between whether you'd rather tool around town in a brand new Corvette, or a fully restored 1960's vintage. They'll both get you from point A to point B, it then becomes a personal choice decision whether you prefer the latest flash, or the nostalgic appeal of yesterday. |
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Post by BBB on Feb 7, 2015 18:09:01 GMT -5
Don't own a Washington, but if I did I'd turn up the modulation by adjusting the (AMC) modulation potentiometer or swapping a different AMC resistor value depending on the version of the radio you have. Then I'd lower the dead key to 2-3 watts. This will actually help make the radio sound louder by allowing the final transistor to "swing" more on the voice peaks. I would not remove the AMC transistor as that usually makes radios sound distorted. If you get the radio, check inside to see if someone else has removed or disconnected this transistor and put it back in.
If you need extra channels, it can be modified as previously mentioned. I'll sometimes pass on a radio for sale that has had the extra channels added if the switches are not hidden in the factory controls or on the back of the rig.
From the Defpom web page:
"This page describes some modifications for the Uniden / President Washington, Stalker IX and Realistic TRC-490 and other radios that use the PC-385 PCB.
How to add more channels
If pin 10 of the PLL is tied low, remove the ground and pull the pin high to go down 64 channels ! (as found in the Washington)
If the pin is tied high, remove the voltage and ground the pin to go up 64 channels !
The state of pin 10 depends on the country that you are in and how it has been modified for the frequencies that are used.
The loop crystal can also be changed to give you more bands of channels if needed, you can use a crystal switch to switch whatever crystals you use to give you the bands that you want.
How to increase the modulation level.
On the Washington and some other versions of the PC-385 board the AMC uses a fixed resistance to limit the amount of modulation that can be produced (typically to just 75% !).
TR32 is the AMC transistor, however, there are two really easy methods of increasing the modulation.
The first method involves replacing the fixed resistor with one of a lower value, the resistor is a 1.5 KOhm and is located directly next to TR33 (it is part number R105, which is not marked on the PCB), it connects between TR33's base (the left leg, one end goes to a diode marking) and earth, replace this resistor with a 500 Ohm.
The second method is better, but, not all models can use it, it depends if the large transformer (marked as T1) is installed towards the rear of the PCB (next to L10), if it is not installed (as is the case with the Washington) you will see a silk screen marking for a preset pot inside the outline for the transformer (some radios already have a VR installed in this location to adjust the AMC), this is what you need to do for this mod:
Remove the 1.5K resistor in the D70 location that is next to TR33.
Install a 1N4148 silicon switch diode in the D70 location.
Install a 1K Ohm preset pot into the vacant position at the rear of the board (next to L10 inside the marking for the transformer).
Connect a jumper wire between the vacant hole that connects to D70 and the vacant hole that connects to the preset pots wiper (it is towards the front edge of the pot).
You have finished, all that needs to be done is to set the AMC level with the new VR (see the alignment instructions for this)"
Hope that helps.
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Post by No Streak on Feb 10, 2015 11:12:51 GMT -5
The Uniden Washington I have has a processor SP-1 in it. Makes it perform well , power wise you can get 6watts tops.
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Sandbagger
Administrator/The Boss
Posts: 6,246
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Post by Sandbagger on Feb 10, 2015 13:00:47 GMT -5
The Uniden Washington I have has a processor SP-1 in it. Makes it perform well , power wise you can get 6watts tops. I assume you mean 6 watts dead key. That would be about right. That chassis is good for about 20 watts PEP power, so the dead key really shouldn't be set above 5 watts if you want to maintain the proper 4:1 100% modulation:carrier ratio without flat topping peaks. |
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Post by No Streak on Feb 10, 2015 13:08:05 GMT -5
Yes sorry 6 watts dead key, I have a Cobra 148GTL old version that was turned up to high on AM and SSB. On SSB the back of the radio would heat up so bad just from talking a couple minutes had turn down carrier watts to 4 watts AM and 12 watts SSB. No problems after that don't want premature failure of components.
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Sandbagger
Administrator/The Boss
Posts: 6,246
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Post by Sandbagger on Feb 10, 2015 19:21:05 GMT -5
Yes sorry 6 watts dead key, I have a Cobra 148GTL old version that was turned up to high on AM and SSB. On SSB the back of the radio would heat up so bad just from talking a couple minutes had turn down carrier watts to 4 watts AM and 12 watts SSB. No problems after that don't want premature failure of components. The other thing people do with those rigs is to turn up the biasing to get a couple more watts out. But by doing that, you end up drawing more current through the final and it'll heat up more. Make sure the bias pots for the driver and final are set to their recommended values which are 25 ma for the driver and 50 ma for the final. |
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Post by sfi355 aka Billy Bob on Apr 9, 2016 21:44:33 GMT -5
I just picked up a Cobra 139XLR, early serial number, All stock, so I had to recap this radio, re tune this radio, Remove the 90 day wonder thick insulator's on the 1306,1307 driver and final, replace 1 2sc1419 regulator, re greased all other transistor's, move some resistor's and the 2sc1419 regulator by the crystal's to stop the drifting, as of right now the radio is sitting on the desk and I used it daily on AM and SSB. I am using a Red Devil Astatic power mic, This radio now play's nice. I have no plans to open up the Voice Lock and no Channel mod's,
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Sandbagger
Administrator/The Boss
Posts: 6,246
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Post by Sandbagger on Apr 9, 2016 22:51:24 GMT -5
I just picked up a Cobra 139XLR, early serial number, All stock, so I had to recap this radio, re tune this radio, Remove the 90 day wonder thick insulator's on the 1306,1307 driver and final, replace 1 2sc1419 regulator, re greased all other transistor's, move some resistor's and the 2sc1419 regulator by the crystal's to stop the drifting, as of right now the radio is sitting on the desk and I used it daily on AM and SSB. I am using a Red Devil Astatic power mic, This radio now play's nice. I have no plans to open up the Voice Lock and no Channel mod's, If that radio is that old of a production run, you might want to check out the technical bulletins that deal with all the updates to that chassis. www.cbtricks.com/radios/cobra/139xlr/index.htmI have that radio and even with the remote regulator mod, it still drifts somewhat with heat. The reason is that the cover lacks sufficient ventilation and allows heat to build up. I had the identical chassis in the Realistic TRC-458 and it had slots all through the top cover for better ventilation and it had minimal drift. You might want to reconsider unlocking the Voice lock for transmit as center slot on mine moves from 11 O'clock to 2 O'clock as the radio heats up. Of course, if you don't run SSB often, it won't matter all that much. Oh, and while you're at it, replace C179. It's a 2.2 uF blue tantalum cap that is known for shorting out. Kills all TX when it does, and it will chatter the relay on AM when you key, or blow the fuse when you key on SSB. |
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Post by 2600 on Apr 14, 2016 15:07:12 GMT -5
Yeah, what he said!
That capacitor won't just "chatter" the relay when it goes bad and shorts, it can damage the contacts. That relay is an Omron type MX3P, made from unobtanium. Be nice to it.
73
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