Kenwood Tkm-707 Mods Online
One major complaint about the stock TKM-707 is the "channelized" feel. You spin the dial, but it snaps to specific 100 Hz or 1 kHz steps depending on the channel set.
After performing your Kenwood TKM-707 mods, you may encounter issues. Here’s a quick fix guide:
| Issue | Likely Cause | Solution | | :--- | :--- | :--- | | Radio shows "Error" after freq mod | You removed the wrong diode. The CPU lost its band table. | Re-install original diodes. Refer to service manual for default config. | | No TX on 10m (28 MHz) | Radio’s LPF board doesn’t include 28 MHz by default. | You need to swap relays on the LPF board or add a 28 MHz external LPF. | | LSB sounds "Donald Duck" (pitchy) | The crystal mod isn’t frequency accurate. | Adjust the trimmer capacitor on the LSB crystal circuit. | | Display dim or flickering | Stock EL backlight failing. | Replace with LED strip mod (12V white LED strip cut to size). | | No output power | Dirty relay on the LPF board. | Tap relay RL1 gently with a screwdriver handle. Desolder and clean if persistent. |
Modifications and Performance Evaluation of the Kenwood TKM-707 Handheld Transceiver Kenwood Tkm-707 Mods
Kenwood used a series of diodes on the logic board to create a "frequency matrix." By grounding certain pins on the microprocessor, you tell the radio what regional version it is (USA, Europe, General). The general export version has the widest TX range.
The TKM-707 has a reputation for slightly muffled receive audio due to aggressive IF filtering meant for noisy boats. The transmit audio is fantastic (the Kenwood "warmth" is there), but you can make it better.
The Fix (Receive): Replace the stock 2.4 kHz ceramic filters (CF1, CF2) with wider Murata filters (2.7 or 3.0 kHz). If you don't want to solder, simply adding a 0.01µF capacitor across the audio amp IC (IC5, pins 2 & 4) boosts the high frequencies. One major complaint about the stock TKM-707 is
The Fix (Transmit): Add the "FM Broadcast" mod. By lifting one leg of R101 (near the mic amp) and inserting a 1k resistor, you flatten the transmit frequency response for a fuller, richer SSB signal.
Absolutely. You can buy a used TKM-707 for $200–$300. After the frequency expansion mod, you have a 150W SSB radio with a receiver that rivals the Icom IC-7300 in terms of dynamic range (the TKM-707 uses a double-conversion superheterodyne with a RF MOSFET preamp).
Compared to modern Chinese 100W radios, the Kenwood is quieter, has no birdies, and produces a clean signal. The only missing features are a spectrum scope and built-in sound card. the Kenwood is quieter
Stock clarifier shifts ±150 Hz. For digital modes (FT8, PSK31) or off-frequency marine nets, you may want ±1 kHz.
The TKM-707 is a 50-watt radio, which is excellent for mobile use but can be overkill for home use or a drain on a vehicle’s electrical system if not managed properly.