Mark III Transmit Tuned by the Receiver

[rescue161]

I inheritted my Grandfathers Golden Eagle Mark III and am finding out a lot about this modified rig.

I bought a Siltronix 90-3 a while back to use with this radio and finally this week, I was able to sit down and wire it up. I was having a very hard time getting the VFO to work. As a matter of fact, I never did. I got frustrated because the Browning was not putting out anything when the VFO was hooked up. I finally unhooked the VFO and did a channel/frequency comparison. Channels 2-15 and 17-23 were all right on the money. Channel 16 did not work at all. Channel 1 put out 27.185 during the first part of my test. On the second time around, it had changed to 27.385. I knew something was odd, because channel 38 is nowhere near what this radio is suppose to be doing. I then realised that I was modifying the transmit frequency with the receivers channel selector!

Once I figured that out, I unsoldered the coax that I put in for the Siltronix and put the radio back together. Further testing shows that the transmitter will go anywhere from 26.955 to 27.605 while on channel 1 and using the receiver to tune it.

Spot does not work as it's already on frequency. however, spot does work on 2-15 and 17-23.

Has anyone ever heard of this mod before?

[Sandbagger]

Dec 12, 2009 9:20:00 GMT -5 rescue161 said:

I inheritted my Grandfathers Golden Eagle Mark III and am finding out a lot about this modified rig.

I bought a Siltronix 90-3 a while back to use with this radio and finally this week, I was able to sit down and wire it up. I was having a very hard time getting the VFO to work. As a matter of fact, I never did. I got frustrated because the Browning was not putting out anything when the VFO was hooked up. I finally unhooked the VFO and did a channel/frequency comparison. Channels 2-15 and 17-23 were all right on the money. Channel 16 did not work at all. Channel 1 put out 27.185 during the first part of my test. On the second time around, it had changed to 27.385. I knew something was odd, because channel 38 is nowhere near what this radio is suppose to be doing. I then realised that I was modifying the transmit frequency with the receivers channel selector!

Once I figured that out, I unsoldered the coax that I put in for the Siltronix and put the radio back together. Further testing shows that the transmitter will go anywhere from 26.955 to 27.605 while on channel 1 and using the receiver to tune it.

Spot does not work as it's already on frequency. however, spot does work on 2-15 and 17-23.

Has anyone ever heard of this mod before?

Wow! I've never seen that one...... Using the receiver's oscillator as a VFO would require a bit of engineering, and additional cabling back to the transmitter. Whoever did that was pretty clever......

[rescue161]

It was pleasant surprise for me when I finally figured out what I had. There is also a push-button on the front of the radio that is labelled "BIRD". I was told that it will make a Tweetie-Bird sound when pressed while the radio is transmitting. It doesn't do anything right now and I'm probably going to just leave it alone.

I haven't taken the receivers covers off yet, but when I do, I'll post some pictures up. I'm curious, but having too much fun with it right now to tear it all apart.

[crazybob]

I once had a Browning Golden Eagle Mark III (about 1992 or 93), that the transmiter VFO knob would swing 10-12 kc's down instead of 700 hz. I got the radio that way. It was nice because we used 26.955 a lot to get away from the skip. I just put the xmiter on CH. 1, & turned the knob to the left.

How is this mod done? Has anyone ever heard of it? ..Sorry to go OT.

[rescue161]

No worries on going off topic. I too am very interested if anyone else has seen this mod.

I'll snap some pics of it tomorrow. Been drinking beer tonight and don't want to screw anything up...lol

[2600]

Have a look inside the receiver, behind the tuning dial for a small pc board that has been potted inside a layer of black silicone RTV, about 2 and a half inches or so square.

There should be the top of a trimmer capacitor visible on the top, and maybe a crystal with no markings on it. I suspect that the crystal's frequency is 30.945 MHz if it is marked.

There is one of these boards around here that we removed from a Mark III receiver ten or more years ago. It also required a modification to the receiver's band selector. The 31.72 crystal would be removed. The second tuneable band above channel 23 would be accomplished by placing an inductor in line with the main dial-oscillator tuning coil. Made the dial calibration above channel 23 wrong, but not by a lot.

I'll snap a pic of the thing if I can find it. The silicone did such a good job of "protecting" the stuff on the pc board that we had to remove the thing. It become intermittent, and removing the black gunk would have been way too labor intensive to be practical.

And the radio that we removed it from ended up with one of the hand-built prototype PLL synthesizers put into his transmitter. And a new 31.72 crystal in his receiver, so the receiver's dial markings would once again line up for all the channels above 23. Besides, he wanted lower channels in the receiver as well. Not sure how well this "receiver-dial" mod would have worked for lower channels. Maybe not so well.

I have no idea who came up with the module that pooped out in this particular radio, nor did the owner have any idea where it came from.

On the other hand, if instead it has a somewhat-larger pc board in the transmitter, with a half-dozen little metal-can transistors with four legs each and a couple of crystals on it, I would love to see some pics of that. Could be a "one-off" we did here around 1985 or so. Proved way too elaborate to duplicate at the time.

73

[rescue161]

I'll snap some pics today. Fixr mentioned that it may have been built by a guy named Ray out of Gastonia, NC. That would make sence, as my Grandfather lived in Spartanburg, SC. I wouldn't imagine that he'd travel too far or mail the radio too far to get the mod done.

[rescue161]

I didn't see the small board behind the tuning dial, but did see a board underneath. Here are the pictures that I took of it. I works like a champ. Just as you described, the tuning dial is "off" a little on one of the bands. The HF dial is spot on, but the CB is off a little. No big deal for me as I've got a freq counter hooked up.