President Madison won't power on

[Jim Dickey]

I think I got the wrong Sam's. I printed it out at work last night and this morning comparing the switch boards, they are completely different. There was only two Madison models on the website, I guess I should have ordered the manual for the 'early' Madison. Here's my serial number:

 

[unit_399]

JIM -

This is in fact a President Madison with the 858 pll. Using the schematic from the Madison with the 8719 pll will not work. The 8719 model did not have a PA/CB switch. It had a Ch 9 switch instead. Totally different animal. You need the schematic from Sams CB-179.

To permanently disable the PA function and permanently enable the NB function on your rig, perform the steps shown in the diagram below. Good luck & 73s.

- 399

 

[Jim Dickey]

That's exactly what I needed!

In your opinion, is the noise blanker too excessive on tuning out distant dx contacts? I was thinking about permanently disabling it, but I'm also running a pretty loud pre amp in front of the CB, so maybe the nb would help with all the extra noise that box picks up.

I've had varying results with nbs on various radios, building this one with the sole intention of dx on 10/11m. Picked up a bunch of Mexican skip the other day which is quite a distance to north Idaho!

 

[unit_399]

Truthfully, I never use the noise blanker on my base stations. Where we live is pretty far from civilization and there's not much noise out there that an NB would help. If you don't want to use it, just disconnect the wires and don't do the mod. Glad I could help.
BTW - your Madison's circuit is exactly the same as the Cobra 139XLR. There is complete tech info for this chassis on CBTRICKS. Here's the link.

http://www.cbtricks.com/radios/cobra/139xlr/index.htm

73s.

- 399

 

[loosecannon]

that is one of the earliest production number Madisons i think i've ever seen.

what is the actual number stamped into the back panel?

00000xxxx?

LC

 

[Jim Dickey]

00000837

I was a little shocked when I saw that too.

I actually got the original external speaker with it too. In the process of recapping right now, one at a time.

 

[sonoma]

these 858 PLL radios are so quiet you do not really need the NB control even where it is not quiet. if set up right it will be dead quiet and some one that will just barely move the s units with a very low signal will just boom in loud. I have 3 of the pres washington radios that I recapped and they are so quiet at times I wonder if they are even working so I will go through the channels just to see if any one is talking on the radio. I can talk to people way off in the distant and some locals around me can not even hear who I am talking too. you get that recapped and tuned right you will be very happy with the radio.

 

[Jim Dickey]

JIM -

This is in fact a President Madison with the 858 pll. Using the schematic from the Madison with the 8719 pll will not work. The 8719 model did not have a PA/CB switch. It had a Ch 9 switch instead. Totally different animal. You need the schematic from Sams CB-179.

To permanently disable the PA function and permanently enable the NB function on your rig, perform the steps shown in the diagram below. Good luck & 73s.

- 399

View attachment 21230

Well my wire colors were a little different than the description but I matched them up by positron on the board and problem solved! I've done about half the caps so far and plugged it back in to check function and everything sounds good. A few more hours on re capping and that'll be done.

As far as attaching the arduino VFO, I think I need to attach it to the reference crystals with a 3 positron switch to select which mode I'm trying to modify frequency on? I just want to cover 28.300-28.500.

Trying to deCide if adding a fm board is worthwhile. I know a lot of people use fm on 10m, but that doesn't seem like a very effective way to dx.

I'm limited to 200w on 10m with my current license so the output on the Madison will be turned down to push a modified KL203 with 13n10s. Hits around 175w out when hooked up to a 3w DK with 10w or so full mod. Right now the Madison is putting out a 6 w DK with about 16w swing, not sure if I need variable power or just a lower bias adjustment. I'm gonna keep using the stock final, when it gives up another 13n10 will go in- I'm kinda a big fan of mosfets

 

[loosecannon]

you are not going to like the phase noise with that VFO.

the 858 chassis is better modified using the programming of the PLL pins themselves.

you can get 10 meters on these radios without messing with the crystals at all, and you will have better, more stable results without having to re-adjust frequency every time you change modes.

here is a pic of my Madison freq counter.
LC

 

[Jim Dickey]

you are not going to like the phase noise with that VFO.

the 858 chassis is better modified using the programming of the PLL pins themselves.

you can get 10 meters on these radios without messing with the crystals at all, and you will have better, more stable results without having to re-adjust frequency every time you change modes.

here is a pic of my Madison freq counter.
LCView attachment 21244

That looks pretty slick! What does the green led next to the counter indicate?

I think your right on about doing PLL instead of vfo. I'm in the process of moving my bench from an out building, into my apartment so I may not get a chance to work on it today.

I painted the back of the factory plexiglass and got some nice fasteners for my counter. Looks a little better anyway.

 

[loosecannon]

while i can't honestly say that i'm a fan of drilling the holes in the front plastic, i also can't say that i've never drilled holes in a radio for a customer.

on my madison, it's not actually a frequency counter, it's a frequency display.
so i misspoke earlier when i called it a counter. (mine is the MB8719 madison BTW)

I didn't like the noise that came along with the multiplexing of the digits on the old blue freq counter i had in there previously. It may not be audible on your radio, but with the LEDs as big as they are in mine, the noise was noticeable.
Also, being mounted right above the volume control doesn't help!

so for this incarnation i chose to go with a display since it won't cause ANY extra noise and i like an ultra quiet receive for DXing.
the caveat is that it won't track with the clarifier, and my clarifier is a 10 turn pot that slides 12khz. (6 down and 6 above the channel) so i needed a way to know when i was actually on the center of the CB channel.
That's what the green LED is. It turns red when you go below the channel, and green when you go above the channel. The circuit doesn't work quite as well as i had hoped, and im still looking for a better solution, but this project is so far on the back burner now that i just kind of deal with it as it does work well enough.

If you take the front panel off, you can see on the inside of the window for the old clock that there is a recess, and you can cut a 1/8" piece of smoke plexi (can buy on ebay)
to fit right in there. This will cut the glare of that counter and hide the insides of the radio better.

also, if that counter is too bright for you, there is probably an IC shaped resistor pack or two that you can increase the value of in order to decrease the brightness.

LC

 

[Jim Dickey]

The LED is an interesting idea. If my preamp is turned off, there might be a light high pitch whine, I honestly didn't operate it much before the freq counter and recap happened. With the preamp on, it drowns out the whine with white noise and whatever happens to be on the freq.

I'd like to do one of those superslide mods on my clarifier, for tx and rx, but am not sure which one to do. Right now I get about 1.3 k up and down, which I assume is the factory setup. The annoying thing is the freq jumps up about 1.2k on tx vs where the rx is set at. it still sounds fine on the scanner, but I cant help but think it would sound better on dx if the freq stayed the same I guess its up to the receiving operator to tune his clarfier to match me at this point.

 

[loosecannon]

your RX TX shift is probably being caused by a misadjustment of VR9.

in the alignment procedure, you see that you need to connect your freq counter to TP8 and then adjust CT4 CT5 and CT6 for the proper frequency in that mode.

after you do this, set the radio to LSB mode, and key the mic with no modulation.
adjust VR9 until your LSB TX freq matches your LSB RX freq.

of course, once you unlock the clarifier then you won't need to do this, as RX and TX will be tied together.

if you do decide to unlock the clarifier, don't try to extend the range with parts changes and things like that. Just remove the connections to the RX only voltage, and move that side of the clarifier to the constant voltage.
reason being, each mode uses its own mixing crystal, so each mode will act differently with regard to the clarifier. extending the range only exacerbates this problem.

here is a link to the circuit i used for my clarifier: http://www.cbtricks.com/pub/secret_cb/index.htm

as i said, it needs some tweaking to work right so if you get it working the way they say it will; please let me know what you did.
LC

 

[Jim Dickey]

Working on a 36' erection right now (Antenna Mast for my astro plane). Once I get the concrete poured in the ground and the coax run, I should be able to get things going on the clarifier and have the Madison hooked up to a tall antenna.

More updates to come.

 

[loosecannon]

hey another Astro Plane fan!
I have run one of those for years and have a few pro tips for you that will increase its performance so shoot me a private message or start a thread on it before you get everything up in the air. I don't want to hijack this thread.
LC