YO3BN - Kenwood TH-F7E

Posted at 8th October 2017

Kenwood TH-F7E

Being a lover of this handheld transceiver, I'd like to put down some notes. I own this model more than a year, so I think I had enough experience with it.

A list with PROS and CONS from my point of view:
PROS:

• small size
• lightweight
• solid plastic case
• intuitive menu
• long battery life with its original 7.4 2000mAh accumulator
• true hi power, has more output power compared with Motorola CP040 UHF and YAESU VX-150 VHF
• low power for close range: 50mW
• clear audio when signal is strong
• AM/FM/WFM/SSB demodulation
• wide RX range: 100KHz-1.3GHz (with no gap I think)
• wide TX range: 137-174MHz; 410-470MHz (with MARS/CAP mod)
• CTCSS/DCS SCAN/SET
• builtin attenuator
• dual simultaneous reception
• VOX

• display glass can be scratched easily
• keypad paint can be easily wiped off
• noisy audio when signal is weak
• intermodulation occurs on VFO B with big antennas, but what can you expect from this small size?
• NARROW/WIDE FM seem to be just a matter of audio level, not filter bandpass or deviation
• being small, it gets hot during long transmit sessions
• sometimes doesn't turn on, can be fixed by removing the battery
• very insensitive within 100-300KHz range
• the rubber cap which covers SPK/MIC/DC-IN connectors decays quickly

Overall its a good portable transceiver. I took it with me in every trip I did and it never disappointed me, many times I've enjoyed listening to SSB QSOs on HF bands with small piece of wire antenna when VHF/UHF bands were dead. Another minuses could be, but I didn't considered them as CONS, long charging time (about 6-8hours), its price and the original antenna which is a poor VHF antenna - it only works reasonable within 437-460MHz (mine), measured with EMF meter.

Accessories

Diamond RH-771 Antenna

Given by a friend (YO9IMR), the RH-771 is a dual band 2m/70cm with wide band coverage antenna. Is a bit long, about 40cm long, but we know that short and tiny antennas are poor antennas. Anyway, it works great with TH-F7E, it beats the internal bar antenna begining with 3.5MHz, so you can have a good reception on HF compared with internal bar antenna. It has good reception on VHF, UHF, broadcast FM band 60-108MHz and 108-132MHz (AirBand). Many times I switch between RH-771 and stock antenna depending where I'm going. For example, if I go down town with friends I'll take the short stock antenna, but if I go on the mountain or on a rugged terrain I'll opt for the RH-771.

Retevis Microphone 2 Pin Mini Rainproof

I've bought two of these from Amazon because they were cheap and had 3.5mm audio output jack which seemed useful to me. I tested only one of them, worked great with my TH-F7E, good audio output, loud and clear modulation, small size.

Retevis R-111 G Type Volume Control

Bought from Amazon too, this earpiece ptt works great with TH-F7E, it can be switched for left or right ear, it has a volume control dial, but the audio is a bit stifled both for microphone and earpiece.

Documentation

My Mods

MARS/CAP Mod

According to above documentation (service manual and "all mods" docs), by removing type settings diode D704 and R701, the transmit range will become 137-174MHz and 410-470MHz.

Morphing TH-F7E to TH-F6A

This mod should unlock TX on 220MHz band for TH-F7E, but...
One tells that TH-F6A and TH-F7E is the same transceiver, others said that some parts are missing on TH-F7E, including firmware. I tried anyway to transform this transceiver. The type setting diode D703 which was left blank by default, has been soldered in place. When first turned on, the transceiver resets itself, but the TX on 220MHz didn't worked.

I have looked on electronic schematic from service manual and there are missing parts indeed between TH-F7E/A and TH-F6A. Not only capacitors, coils and resistors are missing, but the whole part of RF power amplification chain for 220MHz band, including the final RF power transistor too. So, don't dream like I did, the TH-F7E/A could never ever be the TH-F6A !!!

What changed actually, was the B band limits, which they changed according to TH-F6A type, see table below, otherwise almost everything remained the same.

Service Menu

Service menu is used to tune/detune modulation, BFO offset, S-meter, RF power, etc. To enter in Service Menu mode an internal contact need to be closed. It is very annoying or maybe inappropriate to open your transceiver every time you want to enter into Service Mode, so inspired by ohers I placed a micro reed contact internally to close it remotely using a magnet, see pics below:

First, please read documentation, especially Service Manual. I'm not responsible for any damage you can do to your transceiver, you will do it at your own risk!!!

To navigate between service menu, the joystick is used, left/right to switch between options, dial knob or up/down to choose the value and MNU to write the value down to EEPROM. Pressing the LAMP key will turn on the light and enter to the normal menu, other keys work as normally. To exit from service menu the transceiver must be powered off.

I'll not describe again what was written in service manual, thefore please read documentation carefully!!

Below are my default settings from service menu, but note that these settings differs from transceiver to transceiver due component tolerance:

Note that for 220MHz band, the power settings in Service Menu for 6V, 7.4V and 13.8V are all set to FF in EEPROM. Programming them does nothing.

Software & Programming Interface

To be continued ...

73 de YO3BN

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