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CBC International Frequency Expansion Kits





Crystal Oscillator & Electronic Crystal Switch

Expands frequency range of most PLL type CB radios. Adds up to 120 extra channels.*

Perfect for 10-Meter Ham conversions or the type of PLL modifications described in THE CB PLL DATA BOOK.

The EXPANDER 160 is a compact crystal oscillator which allows up to four crystal mixing frequencies to be injected into the PLL synthesizer circuit. This gives a potential of 4 x 40 = 160 channels. Since only one switch is needed, there’s no complicated multiple switching as in binary or BCD PLL expansions, and no skips except for those already in the Channel Selector. A unique wire jumpering arrangement allows the circuit to be used just as a remote crystal switch when the oscillator function isn’t needed, similar to theEXPANDER 240 described below. The small PC board fits inside the radio and connects to the PLL circuit, DC power, and your favorite type of hard switch (toggle, slide, rotary, etc.).


· Buffered oscillator output prevents possible loading effects.
· Wide range crystal trimmers allow exact frequency adjustment.
· Remote diode switching eliminates the problem of stray capacitance found in long wire runs to mechanical switch boxes.
· Simple construction. High-quality PC board with screened parts overlay and solder mask. Kit includes all parts and wires (except crystals and switch) plus detailed assembly and installation instructions.
· For all 23- or 40-channel PLL CBs using a loop mixing circuit. Includes: HD42851, LC7110, LC7113, LC7120, M58472P, M58473P, MB8719, MB8734, MC145f06, MM55116, MC14568, MSC42502P, MSM5907, NDC40013, NIS7261A, NIS7264B, PLL02A, REC86345, SM5104, SM5118, TC5080, TC9102, m PD858 (AM-only), m PD861, m PD2814, m PD2816, m PD2824.

NOTE: Some of these PLL circuits only require the crystal switching function and will also work with the EXPANDER 240.

*Total bandwidth depends upon radio circuitry.




Electronic Crystal Switch

For all PLL type CB radios using a simple crystal local oscillator in the synthesizer mixer circuit. Also for 23-channel crystal-synthesized radios.


The EXPANDER 240 has all the features of the EXPANDER 160, but without the oscillator function (not needed for many conversions) and with 6 crystal positions. This saves you money and simplifies converting radios that don’t require an external oscillator signal. Examples: all 23-channel crystal-synthesized radios, Cobra 140/142GTL type, Cobra 148/2000/2010GTL type, Uniden Grant XL, etc. Other applicable PLL types include the CPI chassis, HD42851, LC7110, LC7113, M58472P, M58473P, MB8719, MB8734, MC145106, MSM5907, NIS7161A, NIS7264B, PLL02A, REC86345, SM5104, TC5080, TC9102, m PD858 (AM-only), and m PD 861 (binary AM-only).


1. Due to the large number of crystal frequencies and mounting possibilities, the crystals and the hardware switch are not included in either kit.

2. The following PLL circuits can’t be modified with these devices: C5121, LC7130, LC7131, LC7132, LC7136, LC7137, LC7185, MB8733, SM5123A, SM5124A, SM5125AM, SM5125B,TC9105, TC9106, TC9109, TC9119.

3. Installation should only be done by a qualified technician with access to the radio’s service manual or schematic.



Manufactured by:

CBC INTERNATIONAL · P.O. BOX 31500 · PHOENIX AZ 85046 U.S.A. · Email:



SUPER EXPO Crystal Oscillator & Mixer





The SUPER EXPO frequency modification kit is perfect for all your HF applications. It consists of a local oscillator which can switch up to 4 crystals of your choice, a mixer stage, and an offset circuit for 10-Meter repeater splits or other duplex operation. Each mixing crystal will generate a complete 23- or 40-channel band, and is fully adjustable with trimmers.

See the Block Diagrams below. To modify frequencies you no longer have to change the program coding or inject new mixing signals inside a PLL circuit, often with complicated retuning procedures. Instead it's now as easy as 1, 2, 3! First, break the PLL's VCO signal at the output side, where a common PC trace or coupling capacitor in the radio leads to the Receive Mixer and Transmit Mixer stages. Then connect the PLL side of the break to the input of SUPER EXPO. Last, connect the output of the SUPER EXPO to the other side of the break. The crystal oscillator in the SUPER EXPO will mix with the radio's VCO to generate a totally new injection signal. This new signal when applied to the radio's RX and TX mixers will change the transceiver's operating frequency.

The right-hand Block Diagram shows that the SUPER EXPO will also modify crystal-synthesized CBs, without having to change a whole bank of crystals. (Doing that would still give you just 23 new frequencies.) Instead, you'll now get an entire 23-channel band of frequencies for each mixing crystal you choose. This means a possible total of 4 x 23 = 92 channels from these great old high-performance rigs! The reason is because you only need to sample from the composite synthesizer output signal that results from mixing all those crystals. (Just like a PLL's VCO output.)

The SUPER EXPO has no effect on the PLL or crystal synthesizer circuits themselves, and these continue to work normally. This includes the Clarifier circuit; you can modify that just as you normally would if the SUPER EXPO wasn't there. So you can stop worrying about things like out-of-lock conditions, accidentally blowing up an obsolete PLL chip, realignment of the PLL or crystal synthesizer, or upsetting the alignment of the USB/LSB offsets. Why? Because you are connected externally to the synthesizer circuit! This greatly simplifies many installations.

Finally, many popular PLL SSB rigs like the Cobra 138/139XLR use separate mixing crystals, one each for AM, USB, and LSB. Which meant you had to change all three of them if you wanted to keep all modes. The SUPER EXPO solves this problem because each mode's carrier frequency is generated inside the loop, and you never touch the inside of the loop.

EXAMPLE OF PLL MODIFICATION: Newer radios like the Courier Galaxy V, Galaxy VI, and Midland 79-265 use the LC7131 PLL chip in a single crystal (10.240 MHz) circuit. Not easily modified until now. The IF is 10.695 MHz, and the Ch.1 AM VCO is normally 16.270 MHz. By mixing this signal with a crystal oscillator of say, 22.725 MHz, you get a mixing product of [16.270 MHz + 22.725 MHz] = 38.995 MHz at the output of the SUPER EXPO. When you mix this product with the 10.695 MHz IF of the radio, the result is a totally new Ch.1 carrier frequency of [38.995 MHz –10.695 MHz ] = 28.300 MHz in the 10-Meter band. Just choose the crystals for the frequencies and/or splits you want.

EXAMPLE OF CRYSTAL RADIO MODIFICATION: Johnson Viking 352, Midland 13-893, 13-895, Pace 1000M, 1000B. These excellent old SSB rigs used banks of 8 MHz and 11 MHz crystals in a very complicated synthesizer circuit. That doesn't matter! The IF is 7.8 MHz, and the Ch.1 USB synthesizer output is 34.765 MHz. By mixing this with your local crystal of say, 14.265 MHz, the result is [34.765 MHz – 14.265 MHz] = 20.500 MHz at the output of the SUPER EXPO. Mixing this 20.500 MHz with the 7.8 MHz IF gives you [20.500 MHz + 7.8 MHz] = 28.300 MHz again.

The SUPER EXPO was designed for maximum circuit flexibility. You can choose several configurations:

1. Straight 160 (or 92) channels: 40 (or 23) channels per mixing crystal.

2. 120 (or 69) channels + T/R repeater offset for 10M FM use: 40 (or 23) channels per crystal in 3 bands, plus one offset band of 40 (or 23) channels.

3. A straight 80 channels for the impossible AM type rigs using the LC7131 or TC9106 PLL (one crystal needed for each mode, RX and TX, resulting in 40 channels for each of the 2 crystal pairs.)

The SUPER EXPO is powered from a regulated +7–10 VDC source in the radio. Current drain is a tiny 13 ma @ 8 VDC. There are only four wire connections to the radio: VCO/SYNTH. IN, RF OUT, +DC, –DC. A fifth wire would be connected to a TX-only voltage source if you plan to use the T/R split feature. Dimensions are 2½" x 3". The quality PC Board has a solder mask and a printed parts legend for easy assembly. Complete kit contains all parts. The 16-page instructions include circuit theory, crystal calculations and suppliers, hookup examples for many popular PLL and crystal CB radios, schematic, parts list and layout, installation and alignment, troubleshooting hints, and more. Just order your crystals, stuff the board, and go! NOTE: Crystals are not included due to the large number of possibilities.


1. A Frequency counter, 30 MHz oscilloscope and service manual or SAMS Fotofacts are required to properly align and install the SUPER EXPO. An RF Signal Generator would also be useful for pre-alignment before installation.

2. The SUPER EXPO won't work with any of the following PLL circuits: C5121, LC7132, LC7136/37, LC7185, MB8733, PLL03A, PLL08A, SM5124A, TC9109. These are generally found in the cheaper AM-only rigs, not SSB types. The SUPER EXPO will work with any PLL circuit using discrete TX and RX mixer stages, including most of the formerly "impossible" chips like the LC7131 and TC9106.

3. Radios with frequency displays (Cobra 2000/2010GTL, Courier Galaxy VI, Uniden HR2510, HR2600, etc.) will not show the modified frequency. The SUPER EXPO inverts the L.O. mixer injection, from high side to low side or vice versa depending upon the radio. The radio’s built-in display only works with the existing VCO frequency and since the SUPER EXPO doesn't affect the VCO, the display won't be affected either.

4. A few older rigs use separate 19 MHz and 34 MHz VCOs for AM/LSB and USB. You can only choose one VCO and therefore one mode (such as USB for 10-Meter Novice use), so check your synthesizer circuit first.

5. The SUPER EXPO may not physically fit inside some of the smaller mobile CBs, so check all dimensions carefully first.

The SUPER EXPO works with all the same radios that can currently use our EXPANDER 160 orEXPANDER 240 kits, as well as the 23-channel and more difficult PLL models. For many radios our simpler kits will do. When deciding which kit to buy, you should consider things like price, size, ease of construction and installation, available test equipment, technical experience, and your need for T/R splits.

 Manufactured by:

CBC INTERNATIONAL · P.O. BOX 31500 · PHOENIX AZ 85046 U.S.A · Email:



EXPANDER 160 & EXPANDER 240 Application Notes

Many people have asked about which expander kit is best for their particular application. Let’s try to clear this up.

Generally speaking, any radio which can use theEXPANDER 240 can also use the EXPANDER 160, but the reverse is not true. That’s because only the EXPANDER 160 includes the oscillator function, which you’d need for many PLL radios. You’d be paying more for an EXPANDER 160in those applications where you really only need the EXPANDER 240’s crystal switching. You might also want to remove the EXPANDER 160 some day and re-install it in another rig that does need the oscillator function, giving you more flexibility.

On the other hand, theEXPANDER 240 has 6 rather than 4 crystal positions and could be used in the older 23-channel radios with crystal synthesizers. In those rigs the EXPANDER 240 would add a total of [5 x 4 related channel groups] = 20 extra channels. (The 6th slot must be reserved for an existing radio synthesizer crystal.) Not very cost-effective for crystal CBs though: there’s the kit cost, the cost of 5 crystals, and the cost of paying a tech to build and install it if you can’t do it. PLL rigs are the most practical.

We call these kits "160" and "240" because any PLL CB using a mixing signal can theoretically have 40 channels per mixing crystal: [4 x 40] = 160 and [6 x 40] = 240, respectively. Few American CBs are broadbanded enough to tune this much range though, with the limit typically 120–130 channels total. For example, the popular MB8719/MB8734 Uniden SSB models will tune a maximum of about 130–140 channels, which means 3 full 40-channel bands, plus a partial band on the 4th mixing crystal. Or two full bands on the two middle crystals and two partial bands on the end crystals, depending on where you set the VCO and mixer tuning stages.

Listed below are many common radios by chassis type, and which kit to use. If your rig’s not on this list, send us a stamped self-addressed envelope (SASE) or E-Mail message with the exact model number. We’ll tell you what if anything can be done to it.


1. Any 23-channel crystal rig. (But only 12 extra channels, where the EXPANDER 240 would get you 20 extra channels.)

2. Any PLL rig using the 15.360 MHz loop tripler mixing scheme. Chips with this method include the LC7120, SM5107, µPD858 (AM 2-crystal scheme only), µPD861, µPD2810, µPD2812, µPD2814, µPD2816, and µPD2824 (SSB).

3. Any late Cybernet PLL02A AM PLL chassis using the 2-crystal scheme of 10.240 MHz and 10.695 MHz. In this circuit the 10.240 MHz PLL reference signal is doubled to 20.480 MHz, and you would replace that signal.

4. Any other PLL rig using a mixing signal that’s not directly derived from a separate mixing crystal. For example all NDI SSB rigs (SBE Sidebander IV, V, Console V, Console VI, Johnson Viking 4730, Messenger 4730, Pace 1000MC/BC, etc.) use a 10 MHz PLL crystal reference, and part of that oscillator signal is sampled off and doubled to 20 MHz to use for loop mixing. In those rigs you’d inject your own new signals in the 20–21 MHz range using an external oscillator.


1. All 23-channel crystal models.

2. Any early Cybernet PLL02A AM PLL chassis using the 3-crystal scheme of 10.240 MHz, 10.695 MHz, and 11.8066 MHz. Here you’d switch in new crystals to replace the 11.8066 MHz signal, which is being tripled to 35.420 MHz anyway.

3. All Cybernet PLL02A SSB American chassis using the 10.0525 MHz mixing crystal, or all "export" multimode chassis using a bank of mixing crystals in either the 10 MHz or 20 MHz range.

4. All the MB8719/MB8734 PLL SSB chassis. Replace the 11.1125 MHz or 11.325 MHz tripler crystal.

5. All the µPD858 AM 3-crystal models. These use 10.240 MHz, 10.695 MHz, and 36.570 MHz.

6. All the µPD858 SSB and SM5104 SSB models. CAUTION! This chassis uses 3 separate mixing crystals, one each for AM, LSB, and USB. Therefore the kit would only work for one mode. That’s fine for 10-Meter Novice conversions if all you care about is USB, but for full CB expansion you’d need three kits for all-mode coverage. Obviously, not very practical.

7. Realistic TRC448, Wards GEN719A: same situation as #6.

10. All Royce models with the "sardine can" type of sealed PLL unit. These generally use a 36 MHz loop mixing signal and the specific PLL chip doesn’t matter. What does matter is that you’d have to run the EXPANDER 240 switching wires into the sealed unit. These wires would be longer than the normal kit mounting location and could cause oscillator instability.

11. Realistic TRC459, TRC480. (Change the 18 MHz mixing crystal.)

12. Any other PLL circuit using a discrete crystal oscillator for loop mixing. You would switch in new crystals to replace that signal. Usually the mixing crystal is around 36 MHz (or a tripled 12 MHz), although a few odd circuits use other crystal frequencies.

For more specific synthesizer details, you might want to order and study the CB TUNE-UP and MODIFICATION REPORTS for your particular radio before proceeding. These include details on suggested new mixing crystals, Clarifier strapovers, peaking, etc.


About the SUPER EXPO...

The SUPER EXPO kit does everything the others do, but is more complicated electrically. The ability for T/R splits makes it more useful for Ham type repeater operation than for CBs. The extra circuitry adds to the building and installation time, and you will need the right test equipment. We don’t recommend it for electronics beginners. See our 2-page catalog ad on this kit for full details.

TEL/FAX: 888-I-FIX-CBs (1-888-434-9227), (831) 333-1800