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President Madison won't power on

So if I unlock the clarifier the rx an tx will be tied together? Seems like an easier fix than re aligning the 3 modes.

I'm hunting for the mod schematic now. The link you posted is to the entire secret CB index, I'm pretty sure I printed out various clarifier tricks for the 139XLR, which should transfer over to old maddi with a few color changes....
 
Jim Dickey said:
So if I unlock the clarifier the rx an tx will be tied together? Seems like an easier fix than re aligning the 3 modes.

I'm hunting for the mod schematic now. The link you posted is to the entire secret CB index, I'm pretty sure I printed out various clarifier tricks for the 139XLR, which should transfer over to old maddi with a few color changes....
Click to expand...
Uh; no. You will still have to align AM, LSB, and USB modes as per alignment instructions. A must.
 
The clarifier is unnaturally easy to mod on this one. Remove a diode and a resistor. The resistor gets strung across two foil pads on the solder side.

This won't put a radio that's drifted with age magically back on frequency.

But if you can tune a SSB station and make him sound right, you'll be transmitting on the same frequency you're hearing.

And if you keep turning the clarifier as far as it goes, and still can't make them sound right you may have to do some alignment after all.

Pull R119 and D30 . Be nice to R119 you need to reuse it.

0Q4SE5.jpg


Here's where R119 gets put back on the solder side.

NlFjaz.jpg


And a wider view of the area shown above.

tNrN9T.jpg


There are further mods you could do, but this lets you line up your transmit with the other stations on the frequency so everybody is on the same transmit frequency at the same time.

And "stretching" the tuning range of the clarifier on this radio is easier said than done.

73
 
Nomad, thanks for posting that!

I was just searching around the forum to link him to that exact procedure.

Jim, listen to Nomad, he's been a guru for longer than i've been in the hobby.
LC
 
Nomad is one of the best techs still out there to date. his postings are hard for some to understand if you are new to radio mods and repairs but he will not steer you wrong. he is very good at giving pictures of the mods also. just like he just did for the clarifier mod above.
 
I found a lot of different instructions for the clarifier on tx. I ended up removing R117 and D30 and moving the purple wire to a point on the board which measured 9.1 VDC. Now the clarifier goes from .3 Khz above Freq to 1.5Khz above freq. I seem to have lost the ability to get dead on freq or anywhere below it. I'm assuming I did something wrong, or the radio needs to be aligned (which we assumed already.)

The instructions I found were from Sonoma on a 858 Washington Thread.
 
Ok. Nomad's method got the clarfier to change TX. Still have the gap between TX and RX.

On Ch21 AM:
RX-27.2150
TX-26.2167

Looks like alignment time. Probably a stupid question but can I align via the Freq Counter on the Channel side or do I need to do it on the Test Points?
 
Jim Dickey said:
I found a lot of different instructions for the clarifier on tx. I ended up removing R117 and D30 and moving the purple wire to a point on the board which measured 9.1 VDC. Now the clarifier goes from .3 Khz above Freq to 1.5Khz above freq. I seem to have lost the ability to get dead on freq or anywhere below it. I'm assuming I did something wrong, or the radio needs to be aligned (which we assumed already.)

The instructions I found were from Sonoma on a 858 Washington Thread.
Click to expand...

. . . yup . . .
 
you said you have 9.1 volts on the clarifier, does it stay the same on TX and RX. if the voltage varies it can change the freq some.
 
You have discovered one of this radio's odd quirks.

You should find that your transmit and receive frequencies line up to each other just fine on USB and LSB.

But in this radio, AM is different. Trimmer cap CT5 sets LSB mode to center the clarifier on frequency. CT4 sets USB, but ALSO your AM transmit. Only the transmit side of AM mode is set (also) by CT4.

AM receive is set on frequency with CT6. This one has no effect you can see while transmitting. It sets ONLY the receiver frequency on AM. Nearly every 40-channel radio made since 1979 is different in this respect, where you have three trimmers. One for AM, one for USB and one for LSB.

But not this radio.

73
 
nomadradio said:
You have discovered one of this radio's odd quirks.

You should find that your transmit and receive frequencies line up to each other just fine on USB and LSB.

But in this radio, AM is different. Trimmer cap CT5 sets LSB mode to center the clarifier on frequency. CT4 sets USB, but ALSO your AM transmit. Only the transmit side of AM mode is set (also) by CT4.

AM receive is set on frequency with CT6. This one has no effect you can see while transmitting. It sets ONLY the receiver frequency on AM. Nearly every 40-channel radio made since 1979 is different in this respect, where you have three trimmers. One for AM, one for USB and one for LSB.

But not this radio.

73
Click to expand...


So what I'm reading is that I can either have a perfect TX/RX match on USB OR AM? Kind of a tough call to make. I thought I had remembered reading something funny about Freq. offsets on this radio, thank you for the clarfication.

How much loss in usable performance am I giving up with the 1.2-1.7 ish Khz offset on AM? My scanner set to the RX frequency picks up the offset TX just fine, sounds good, but I'm testing with the scanner about 40 ft from the antenna. Not sure that qualifies as DX. I would like to use both modes, especially since this radio will eventually work both 10 and 11 meter DX.
 
Okay, setting CT4 should put your USB transmit and receive both on frequency. It does one more thing, though. At the same time it sets the AM transmit frequency ONLY. Has no influence on AM receive frequency. But so long as USB is set on frequency, your AM transmit (only) will be as well.

CT5 will put your LSB transmit and receive on frequency.

CT6 will affect ONLY the receive side of AM mode. Won't affect transmit at all. You just have to set CT6 to get AM receive on frequency separately from getting the AM transmit on frequency. CT4 already took care of the AM transmit frequency if you have set it for USB.

Or, just set CT4 to put AM transmit on frequency and don't worry about USB. If AM is set right, USB can't be very far off.

73
 
nomadradio said:
Okay, setting CT4 should put your USB transmit and receive both on frequency. It does one more thing, though. At the same time it sets the AM transmit frequency ONLY. Has no influence on AM receive frequency. But so long as USB is set on frequency, your AM transmit (only) will be as well.

CT5 will put your LSB transmit and receive on frequency.

CT6 will affect ONLY the receive side of AM mode. Won't affect transmit at all. You just have to set CT6 to get AM receive on frequency separately from getting the AM transmit on frequency. CT4 already took care of the AM transmit frequency if you have set it for USB.

Or, just set CT4 to put AM transmit on frequency and don't worry about USB. If AM is set right, USB can't be very far off.

73
Click to expand...

The RX/TX for USB and LSB are dead nuts on, maybe 50-100hz off but I don't have the resolution on my counter (it just flickers back and forth between 2 digits). The clarifier is now working as it should on all modes.

I have a separate issue with AM receive power, but for now plugging in the preamp seems to fix it (another project for another day). The USB and LSB power the external speaker just fine, AM barely buzzes with RF gain and Volume all the way up. If I attach the preamp, AM voulme goes up to a comfortable listening level but not nearly as loud as the Sidebands.

Ok, this is probably a dumb idea and feel free to tell me why (that's how I learn), but what if I took CT6 (RX) High to match the TX high offset? Then Dialed everything back down with the clarfier?

It would seem like matching CT4 to desired AM TX freq would lower the USB TX by 1.7 Khz, which would put it right back in the middle of the band.

It sounds like I have a choice to make on which mode will work perfectly (or as close as I can get) and which mode will work adequately...
 

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