Realistic Trc-474
This is one of the so-called un-modifiable CB radio's that utilize the TC9106 PLL chips from the mid 1990's, which can not be modified by changing the programming pins directly because this PLL will shut down the second it notices it has been tampered with.
So, what do i intend to do with this radio?
My intentions are to convert this un-modifiable CB radio so that it works on the 10 meter ham band.
The radio will either be used for a beacon project "BIG MAYBE" which would run on 28.196mhz, or just for the hell of trying to convert the radio to 10 meters.
How do i intend to modify the PLL?
Ah, that is the interesting part of the project.
The PLL will not be modified directly, the changes will be made by swapping out 10.240mhz crystal which in turn will change the operating frequency for this radio! As of right now i currently have the radio transmitting working on 28mhz thru my home brew dummy load, which has been tuned up to provide around 4-5watts output.
The big thing with converting this radio to 28mhz, is that the receiver will most likely be deaf. Fortunately i stumbled across forum, where the chap had the same problem with the receiver, he devised a plan to remove the 10.7mhz filter and replace with a ceramic cap of some value.
You know me, gotta get in there and have a go at it. So i pulled out the 10.7mhz filter and tossed a 455khz resonator in it's place, receive was back with a little tuning on the receiver circuits, but where was she receiving at? Good question, still trying to figure that one out!
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28mhz Conversion for Realistic TRC-474
10.240mhz crystal swapped out for 10.695mhz crystal
What frequency range did i come up with?
Below is the current frequency ranage that i managed to get the radio tuned for on the transmit side anyways:
Transmit frequency range: 28.160 - 28.620mhz +/- 5khz
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Ch 1 28.160
Ch 2 28.170
Ch 3 28.180
Ch 4 28.200
Ch 5 28.210
Ch 6 28.220
Ch 7 28.230
Ch 8 28.250
Ch 9 28.260
Ch10 28.275***
Ch11 28.280
Ch12 28.300
Ch13 28.310
Ch14 28.320
Ch15 28.330
Ch16 28.350
Ch17 28.370
Ch18 28.380
Ch19 28.390
Ch20 28.410
Ch21 28.420
Ch22 28.430
Ch23 28.460
Ch24 28.440
Ch25 28.450
Ch26 28.470
Ch27 28.480
Ch28 28.490
Ch29 28.505***
Ch30 28.510
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Ch31 28.520
Ch32 28.530
Ch33 28.540
Ch34 28.550
Ch35 28.560
Ch36 28.570
Ch37 28.580
Ch38 28.590
Ch39 28.610
Ch40 28.620
Beacon coordinator email messages:
On 3/10/2019 7:17 AM, Darrell Steele wrote:
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Good morning. Darrell here.. "VO1MDS", i recently had a look on your website regarding 10 meter beacons and a listing for me for 28.196mhz and marked as QRT as of 2014. Just so you know, i now have plans to reactivate this beacon once again.
Question: Would I be able to use a AM rig to send a beacon message?
What would happen is the radio would be steady keyed while the CW audio message would be sent thru the mic jack from a audio recording device.
Any input from you would be great.
Thanks again. All the best.
Regards: Darrell Steele
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Good Morning Darrell,
Certainly your beacon re-activation would be a valuable asset for indicating propagation conditions. Your message brought a smile as many years ago I spent a few days at Harmon AFB.
That's exactly how I do the beacon message....By keying the carrier of an AM only rig to produce a clean message. I'm not aware of Canadian rules regarding continuous carrier and imputing a recorded message but that means is not legal in the USA. ....
If older CB radios are available an economical beacon can be activated at minimal cost and maximum longevity. My beacon has been in 24/7 operation since 1992 and the first converted CB rig lasted 11 years before it "smoked".. A look into my page for directions and converting information.
I am no longer the IARU Region 2 HF Beacon Coordinator but, I will Bcc him your initial message.
Beacon questions?....Please ask.
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Good morning Darryl,
I just received a forwarded email from -------, and your discussion becoming beacon operational again. That is great. We need more DX from Canada!
It appears that you are still working on getting your equipment organized.
----- is absolutely correct about keying the push to talk (PTT) , on an old converted CB rig thereby the keying the carrier for a nice clean Beacon CW note. I'm using a 40 year old converted Midland CB rig, and have had it in operation for about 2 years now. I think there is a new 10/11 meter CB rig = " AnyTone brand" that will get to 10 meters and all you do is key the mic. But as a caution, I have never gotten involved doing this conversion and therefore cannot provide you with instructions should you have any problems.
So, after you've had the chance to organize your equipment and ready to begin on the air, I can then suggest you a frequency without delay. It is policy at this time to not suggest beacon frequencies until persons are ready to operate because some do not become operational and a frequency was lost. Hope you understand. Please let me know.
73 Denny
WI5V Region 2 Beacon Coordinator
Others that tried to modify the Trc-474
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