This information is
supplied for educational purposes only!
Please Note: This
information is for educational purposes
only and is not an endorsement of the
information supplied. I assume no
liability or responsibility with respect
to the use of such information. So if you
try some of the articles on your own
equipment,
it's on your own risk.
Be aware of the type acceptance
laws and the FCC Rules and Regulations.
Performing modifications of some
equipment may be a violation of local
laws. If you have any doubts, do not
perform the modification.
TM255
and TM455 discussion group
MODS FOR THE
KENWOOD TM-255E
My Kenwood
MODs:
Adjust
LOW power setting
The way to adjust low
power is to regulate VR401. This
trimmer can be found under the
speaker (regulates power between 2
and 30 watts).
Adjust HI power
setting
To regulate the power of
the HI position is to adjust VR601.
You can find this trimmer on the back
left side (remove top and locate the
alu cover).
Please be carefully when you dismount
and locate the trimmer.
Adjust
TX-Power/SWR ratio
At the same place you
can find VR603 and that is the SWR
protection control. Be carefull when
adjusting this trimmer, because it
protects your transceiver against bad
SWR, but can be usefull when power
drops to much on relative good SWR.
Adjust AGC
To adjust the AGC time
constant of the transceiver locate
VR402 that can be found on the left
side at the center when removing the
top.
Bulb voltage
Each lightbulb (Display lighting) has
a voltage of 6 volts which are
connected in pairs (in serie making
it 2 x 6v = 12v).
Improved audio
quality with the MC-44/45 that comes
with the TM255/455
Replace C1 (33nF) with a 100nF. This
capacitor can be found down left
corner.
View picture of this microphone mods
Note:
Please be carefully with
these adjustments! All modifications
you make is totaly at your own risk.
If you
have any other mods for this good
transceiver then please contact me.
ON6MU
You'll find
lots and lots more in our TM-255/455
discussion group
MORE TM-255E MODS
Solution 9k6
TM-255/455
Dear
OM's
This is what I found a service
technical report from Kenwood acc.
TM255 and TM455 9600bps Date November
8, 1994
SUBJECT:
Countermessure against modulation
during packet 9600bps operation with some
older models.
Phenomenon:
A trouble modulation malfunction
during packet 9600bps operation was
found in the manufacturing process
even trough there in input in the
DATA terminal.
Pay heed to this trouble in replacing
the analog switch IC13.
Cause:
This trouble is cuased by variation
in the analog switch IC13.
Even if the 9600bps SW
Tr.(Q20:DTA124EK) has been turned ON,
the analog switch IC remains
unstable.
Counter messure:
We decided to raise the analog switch
IC13 voltage while the 9600bps SW TR.
(Q20:DTA124EK) is in action by
changing the chip resistor R117 in
the TX-RX-unit of TM455A/E and of
TM255A/E.....etc.
R117=10K to be replaced with 3K3
So if you have problems with those
two say to your dealer to ask for
SERVICE TECHNICAL REPORT No.
B510-94-081E page 1/2 and page 2/2
73's DE PAT KE6MIQ
TM-255E
service menu
BEFORE
ANYTHING: write down the original
values, just in case!
To enter service menu :
Hold down NB and MHz keys + Power ON.
Turn the Frequency Tuning knob to
change menu number.
UP/DOWN keys to change value
>
>A0 Checksum diplay
>A1 RIT center
>A2 IF-Shift center
>A3 LSB carrier point
>A4 USB carrier point
>A5 S-meter adjust S1 (not FM)
>A6 S-meter adjust S9 (not FM)
>A7 S-meter adjust full (not FM)
>A8 S-meter FM start
>A9 S-meter FM full scale
>AA RF-meter adjust low
>AB RF-meter adjust middle
>AC RF-meter adjust high
>AD DTSS single tone frequency
>AE ALC start (microphone gain
control by ALC)
>AF ALC zone max (microphone gain
control by ALC)
>B0 ALC zone +6dB (microphone gain
control by ALC)
>B1 Microphone gain level FM
>B2 Microphone gain Level SSB
>B3 Write to Eprom by pressing UP
or DOWN key.
More mods and info, tips and tricks
at http://groups.yahoo.com/group/tm255/
73"
Guy
TM-271e
Specs:
FM VHF transceiver
60watt/25watt
meets the strict U.S. Department of
Defense MIL standards
200 memory channels
DTMF microphone
Multi functional menus and options
High quality front speaker
Memory name function
High frequency stability (build-in
TCXO)
1200/9600 baud packet
To change
& adjust the maximum (low and
high) output RF power:
- Remove
the plastic cover,
- Remove
the rubber waterproof seal,
and remove the 8 screws on
the aluminum cover.
- Set
the radio so that the front
is facing you.
- Locate
VR1 (measure approx. 5cm from
the right and 5 cm from the
back)
- Rotate
VR1 counter-clockwise to
reduce the ouput power
towards the setting you
desire
Note: the relation between
the low- and high power
setting is about 2,5 x.
Example: If your maximum
power is set to 50 watts your
low power setting will be
around 20 watts
- Review
http://www.ham.dmz.ro/kenwood/tm-271a.php
- Manual
here
Featuring
Today's highlight!!!:
Discover the unique features of deepspace
MDSRadio: MDSRadio
TM-441e
Kenwood
TM-441e 9600 baud modification
(improved version de ON6MU)
How to use the
Kenwood TH-D7e, TM-D700 or TS-2000 with
GP 1.63 (Graphic Packet)
You
can download a special DOS utility
that I programmed to select and
configure the TH-D7, TM-D700 or
TS-2000 for 9600 baud or 1200 baud in
use with GP. Easy to use and makes
all the needed configurations for
you.
Download GPKTNC11.ZIP .
Simply
install all the files in your
GP-directory and run GPKTNC.EXE and
follow the instructions on your
screen.
FreeWare!
YAESU
FRG-100
RX expantion
The new RX Yaesu FRG100
is a very good receiver. The
specifications are: frequency 130 KHz
to 30 MHz, but 30 KHz to 30 MHz is
also possible if you:
Press
and hold the folowing keys while
turning on POWER.
<<
AM and SSB keys >>
FRG-100 AGC
much faster
To improve the original
AGC and make it even faster as it is:
Remove
the top cover
The C1225 1uF/50v capacitor is
located on the main board in the left
region about 5-6 cm from the S-meter
(near a two pole connector)
C 1225
(original 1 uF ) replace with 100 nF
It
works really very well!
Improved
audio with following mods:
Replace
C1183 (near de TDA2003 10 watt
amplifier) with a 3n3 capacitor.
Solder parallel over R1165 a 47nF
capacitor
View picture -> FRG-100 audio mod
This modification will improve the
higher end of the audio spectrum,
making the sound clearer (less
"muddy").
Added
09/09: Improved sound clearity by
adding a 47uF/50v elco in series with
the speaker inside the Frog. The
resonance of the case enhances the
low-mids of the spectrum. This super
simple modification clears the audio
of the inside speaker much. The plus
of the elco is soldered on the red
wire, the minus on the speaker (where
the red wire was connected).
Bass responce
of FM audio of FM-unit-100 mod:
To
improve the bass responce of the
audio in FM mode you need to
place/solder a 100nF capacitor
parallel over C4007 (0.0047uF) and a
10nF capacitor parallel over C4008
(0.022uF) in FM-Unit-100.
Fix / reduce
CPU noise and power supply
interference:
I've
got my radio for more then 10 years
now, and just recently I noticed a
kind of hiss (hum, electrical
interference kind of noise) with no
antenna connected. After connecting
the Frog to a battery to be sure it
wasn't the power supply, I was sure
it had to be inside the FRG and
probable a ground type of fault. And
surely it was! Grounding the CPU
shield (bottom board) to the chassis
reduced it by 60%. After loosening
all screws on the top print board and
the screws holding the bottom print
board, put some contact cleaner on
each hole and tighten all screws
again. Humming sound gone. I've got
the CPU interference better then
original by soldering a little wire
from the CPU shield to the chassis - picture and by using a
shoke on the power connecter - picture (using a
ferrite rod and about 7 turns of the
power cable around it)
Note:
Please be carefully with
these adjustments! All modifications
you make is totaly at your own
risk.
DRM Reception
with the FRG-100:
DRM
mods: 455 Khz MF to AF
converter used for DRM reception in a
Yaesu FRG-100 receiver
Specs http://www.thiecom.de/pdf/FRG_100.pdf
Schematic http://www.thiecom.de/pdf/frg100-diagramm.pdf
Review http://www.eham.net/reviews/detail/476
Group: http://groups.yahoo.com/group/frg-100/
DRM Mod: http://www.kb2ljj.com/data/yaesu/frg-100.htm or here
Featuring
If you
have any questions
then please contact me.
Realistic
DX-100L
An analog
AM/CW/SSB receiver
Produced in 1981
Coverage: 150...30000 KHz
Improve
audio, SSB tuning and more mods:
modifications
and extra info...
Yaesu
FT-817ND
Yaesu broke new
ground with the introduction of the
FT-817: the world’s first
HF/VHF/UHF self-contained
battery-powered Multi-mode Portable
Transceiver. Providing up to five
watts of power output, the FT-817 is
designed for operation on the 160-10
meter HF bands, plus the 6 meter, 2
meter, and 70 cm bands. Whether your
preferred operating mode is SSB, CW,
AM, FM, Packet, or SSB-based Digital
modes like PSK31, the FT-817 is ready
to join you on your next hiking,
camping, or search-and-rescue
adventure!
Yaesu FT-897D
The FT-897D is a rugged,
innovative, multiband, multimode
portable/base transceiver for the
amateur radio MF/HF/VHF/UHF bands.
Providing coverage of the 160-10
meter bands plus the 6 m, 2 m, and 70
cm bands, the FT-897 includes
operation on the SSB, CW, AM, FM, and
Digital modes. It's capable of
20-Watt portable operation using
internal batteries, or up to 100
Watts when using an external
13.8-volt DC power source!
The FT-897 includes a wide array of
analog and DSP filters to help you
dig out those weak DX signals on a
crowded band! One-touch activation of
the DSP filters, plus a convenient
“DSP” LED on the front
panel, enhance the ease of using the
DSP. DSP Bandpass Filters, Noise
Reduction,a nd Auto-Notch Filter
circuits are included.
Kenwood TM-251
The Kenwood TM-251A
series include dual band receive
capability. The TM-251A and TM-451A
can switch between 144 MHz and 440
MHz on receive. They also feature
packet compatibility for 1200 or 9600
bps accessible from the rear panel.
There are 40 memory channels plus 1
call channel, and all can be used to
store transmit and receive
frequencies as well as repeater and
signaling data. The built-in digital
recording system enables automatic
storing of a signal picked up by the
radio for later playback (for two 8
second messages). The TM-251A
transmits on 2 meters with three
output power levels: 5/10/50 watts.
- Cross-band
Repeater:
The TM-251/451 transceivers
are capable of operating as a
"Fixed Direction"
repeater and as a "In
Band" repeater.
Operation:
1. Preset the desired
operating frequencies for the
VHF and UHF bands.
2. To turn menu function
number 69 "ON."
Fixed
Direction Operation:
During repeater operation,
any signal that is received
on the Sub band that is
strong enough to open squelch
will be retransmitted on the
Main band. For example a
signal that is received on
the UHF receiver of a TM-251
will be retransmitted on the
VHF band.
In Band
Operation:
During repeater operation,
any signal that is received
on the Main band will be
recorded by the DSR system,
up to a maximum length of 16
seconds. After the signal
drops out the contents of the
DSR system will be
retransmitted.
Repeater
Transmit Hold Time:
The transmitter can be
adjusted to remain keyed for
500 mS after the incoming
signal drops out. Or can be
adjusted to unkey immediately
after the input ceases. This
is selected, using menu
function 70. When the
function is ON transmit is
held for 500mS. When the
function is OFF the
transmitter drop some
immediately.
Note: during repeater
operation all decimal points
in the display will be on, as
a visual reminder you are in
a repeater mode.
To cancel a repeater
operation turn menu function
number 69 "Off"
- Group TM-251/TM-451
TM-261/TM461 TM-241/TM-441
- Mods http://www.kb2ljj.com/data/kenwood/TM-251_A_E.htm
MFJ-9406x
An analog SSB/CW
transceiver
Coverage: 50.000...50.305 MHz
Power: 10 watt
Peak amps: 2A
MODS
Digital Frequency read-out: My mod to
connect a frequencycounter to an
MFJ-9406
MFJ -9406 SQUELCH CONTROL mfjsqelch.zip
MFJ CW ADAPTER mfjcw.zip
CONDOR 16
Old VHF mobile
transceiver
1/10 watt
FM
My Condor16
info and mods page
Kenwood
TH-215/TH-415
To get the unfiltered LF
output from the TH-215/415 Kenwood
portable you need to get to pin 9 of
IC1 (TA7761P).
You could use the unused mic
connector pin that feeds the top pin
of a 3.5mm jack. You need to remove
the SMD 220 Ohm resistor too (mine
was 47 Ohms) which can be found
beneeth the mic connector.
MODS
TH-215/TH415 mods
for wide LF 9k6 output from
discriminator TA7761
TS-120S
Power: 100 Watt
Bands: 80m, 40m, 20m, 15m, 10m
Modes: CW/USB/LSB
Features: Vox, RF ATT, NB, RIT,
RF-gain, optional CW filter, external
VFO etc...
LINKS TO MUCH MORE HAM MODS
HAM RADIO EQUIPMENT
MANUFACTURES
Icom
IC-T7e
A dualband FM portable
VHF/UHF
144...146 & 430...440 Mc
0,5 watt, 1 watt, 3 watt
40 memory channels
DTMF, Tone, CTCSS
Some examples of
antennas
A directional
antenna with high gain (Yagi) 
And how to build
them on my homebrew site
FADA
652
Antique
Radio Homepage
Don't miss
this!!
.
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