Yep, another way. Just found it out today.
If you want a 10 meter radio that's channelized or if you don't want to try your hand at computer science, try this modification instead! The cost: Well below $10 or even $5. The candidate: A Midland 13-866 (or the 853 if it gets fixed).
Overview
Let's take the Midland 13-853 or 857 mixing scheme again. The ones that use the 23-14-11MHz mixing scheme are the ones you'll want to do this mod on. Other models include the Cobra 19 and 21 series as well.
Channel 1 on CB is on 26.965MHz. The Midland has a 4x6 crystal matrix, with one bank full of 23MHz crystals and the second full of 14MHz crystals. Transmit and Receive offsets are made using 2 11MHz crystals 455KHz off from one another.
For transmit:
23.290 + 14.950 = 38.240 - 11.275 = 26.965MHz
For receive:
23.290 + 14.950 = 38.240 - 11.730 = 26.510MHz (455KHz offset)
Cool, right?
Well if you changed the offset crystals from 11MHz to 10MHz, you can shift the transmit receive up into the 10 meter ham band! The CW and possibly phone portion, at that. All it requires is a 10.240MHz crystal (easily sourced) for transmit and a 10.695MHz crystal (again, easily sourced) for receive. Now the only things that need retuned are the cans for 11.275MHz and 27MHz. Retune to 10.240MHz and 28MHz.
Search Mouser Electronics for 10.240 and 10.695MHz crystals. They are less than a dollar a piece and are made by IQD, a UK distributor. If you want to operate on frequencies that end in 5 (28.005, .015, etc), purchase 10.7MHz and 10.245MHz crystals. These too can be sourced on Mouser. Be careful with this mod as Channel 1 will be on 27.995MHz - just barely outside of the 10 meter band. It's tempting, but we must be considerate and polite to our bandwidth adherence.
You can also mix crystal types as well, such as HC49/U with HC49/S. Just make sure they are the same electrically.
Here's the channel plan for the modified circuit:
CHANNEL 1:
23.290 + 14.950 - 10.240 = 28.000MHz (TX)
23.290 + 14.950 - 10.695 = 27.545MHz (RX)
CHANNEL 2:
23.290 + 14.960 - 10.240 = 28.010MHz (TX)
23.290 + 14.960 - 10.695 = 27.555MHz (RX)
CHANNEL 3:
23.290 + 14.970 - 10.240 = 28.020MHz (TX)
23.290 + 14.970 - 10.695 = 27.565MHz (RX)
CHANNEL 4:
23.290 + 14.990 - 10.240 = 28.040MHz (TX)
23.290 + 14.990 - 10.695 = 27.585MHz (RX)
CHANNEL 5:
23.340 + 14.950 - 10.240 = 28.050MHz (TX)
23.340 + 14.950 - 10.695 = 27.595MHz (RX)
CHANNEL 6 (QRP Calling Frequency):
23.340 + 14.960 - 10.240 = 28.060MHz (TX)
23.340 + 14.960 - 10.695 = 27.605MHz (RX)
CHANNEL 7:
23.340 + 14.970 - 10.240 = 28.070MHz (TX)
23.340 + 14.970 - 10.695 = 27.615MHz (RX)
CHANNEL 8:
23.340 + 14.990 - 10.240 = 28.090MHz (TX)
23.340 + 14.990 - 10.695 = 27.635MHz (RX)
CHANNEL 9:
23.390 + 14.950 - 10.240 = 28.100MHz (TX)
23.390 + 14.950 - 10.695 = 27.645MHz (RX)
CHANNEL 10:
23.390 + 14.960 - 10.240 = 28.110MHz (TX)
23.390 + 14.960 - 10.695 = 27.655MHz (RX)
CHANNEL 11:
23.390 + 14.970 - 10.240 = 28.120MHz (TX)
23.390 + 14.970 - 10.695 = 27.665MHz (RX)
CHANNEL 12:
23.390 + 14.990 - 10.240 = 28.140MHz (TX)
23.390 + 14.990 - 10.695 = 27.685MHz (RX)
CHANNEL 13:
23.440 + 14.950 - 10.240 = 28.150MHz (TX)
23.440 + 14.950 - 10.695 = 27.695MHz (RX)
CHANNEL 14:
23.440 + 14.960 - 10.240 = 28.160MHz (TX)
23.440 + 14.960 - 10.695 = 27.705MHz (RX)
CHANNEL 15:
23.440 + 14.970 - 10.240 = 28.170MHz (TX)
23.440 + 14.970 - 10.695 = 27.715MHz (RX)
CHANNEL 16:
23.440 + 14.990 - 10.240 = 28.190MHz (TX)
23.440 + 14.990 - 10.695 = 27.735MHz (RX)
CHANNEL 17:
23.490 + 14.950 - 10.240 = 28.200MHz (TX)
23.490 + 14.950 - 10.695 = 27.745MHz (RX)
CHANNEL 18:
23.490 + 14.960 - 10.240 = 28.210MHz (TX)
23.490 + 14.960 - 10.695 = 27.755MHz (RX)
CHANNEL 19:
23.490 + 14.970 - 10.240 = 28.220MHz (TX)
23.490 + 14.970 - 10.695 = 27.765MHz (RX)
CHANNEL 20:
23.490 + 14.990 - 10.240 = 28.240MHz (TX)
23.490 + 14.990 - 10.695 = 27.785MHz (RX)
CHANNEL 21:
23.540 + 14.950 - 10.240 = 28.250MHz (TX)
23.540 + 14.950 - 10.695 = 27.795MHz (RX)
CHANNEL 22:
23.540 + 14.960 - 10.240 = 28.260MHz (TX)
23.540 + 14.960 - 10.695 = 27.805MHz (RX)
CHANNEL 23:
23.540 + 14.990 - 10.240 = 28.290MHz (TX)
23.540 + 14.990 - 10.695 = 27.835MHz (RX)
If you'd like to fine tune these frequencies or you're not comfortable with the skip in channels, you can add in small trimmer capacitors on the crystals, however I don't think it'll be necessary. It shouldn't really matter here as the very low portion of 28MHz is PERFECT for CW work. Even better, if your rig has Delta Tune, you should be able to tune above or below for better reception.
Of course, adding in a BFO is a must if this is to be a CW radio. Make sure to inject it near the IF stages or directly on the input of the detector diode coming off of the IF stages.
A simple sidetone can be built into the existing radio circuitry. I'll update this page with a conceptual design if it succeeds.
No need for computer programming here - do it like your grandfather did! Just swap out two crystals, give the radio a retune, and bam - you're on 10 meters!!!
You know what else is cool? This radio can be used as a propagation beacon when you're not using it for QSOs. In the region I'm in, 10 meter beacons can be found between 28.100 and 28.300MHz - in this case, Channels 9 through 23. Of course you can still operate CW on these frequencies.
How can you do it? Look for or build your own automatic keyers - PICAXE, Arduino, computer controlled...the sky's the limit! If you do use this radio as a beacon, be sure to check that you don't need to register. Some regions, if not all, require that you at least register your beacon before putting it on air. For temporary use, you don't necessarily have to register.
As of April of 2025, 23 channel CBs on eBay are popping like popcorn - get an AM-only one here or look at yard sales, convert it, and get on 10 meters! It's burning hot, on fire right now!!!
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