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Here is a draft verson of this document. The info is correct, but i need to
scan some things, and take some SINAD mesurements yet.
DO NOT POST THIS ANYPLACE IN CYBERSPACE!!!!!!!!!!!!!!!!!!
You will be able to do this with the final verson. I hope I can trust people
to do this. If not I will not post drafts anymore.
- ---------
Here is the mod to restore your HT to full coverage.
The first we "trick" the cpu to think it is in a test mode on each band. Then
the 440 mother board must be modifyed to switch the incoming rf into a divide
by 2 prescalier. the out put of this is then fead into the 440 reciver like a
normal 350-500 MHz signal.
Here we go with the first part of the mod.
Going throu with this will cause the cpu to be reset and clear all the memory
information. Make a back up of the radio first if you dont want to loose any
thing.
1. Open up the radio
a. Remove the Knob and the lock nut from around the shaft. I find a
small screw driver to work well for this. If you have a spanner
wrench use it!
b. Remove the screw from in between the mic and speaker jacks.
c. Remove the 4 screws from the back metal pannel, and the 4 screws
from the plastic L cover over the back of the key pad.
d. Remove the battery release tab from the back, and the 2 screws
securing the L cover to the metal back cover.
e. Remove the front cover, beeing carful not to loose the gasket.
f. Release the flat ribbon cable from the Main Unit. Then angle the
Main unit upwards and pull it away from the radio.
2. Change the solder jumpers on the radio.
a. There are 7 jumpers next to the the sub cpu, Q1001 aranged in the
below fassion:
() JP1001
() JP1002
() JP1003
() JP1004
() JP1005
() JP1006
() JP1007
b. If you open solder pad JP1006 you will have extended transmit,
JP1007 will allow you to change the Band and IF selection in the
internal allinment menu. (more on this in the next part of the
mod.)
JP1004, if closed, will give you a tone burst inplace of the
monitior
switch, and vice versa.
c. To make this mod work, you must open JP1006, and JP1007.
3. Once the jumpers are configured, reassemble the radio temporaly.
a. Incert the MAIN Board into the alumion pannel and attach the ribon
cable to the main unit.
b. Replace the front cover and L cover, and secure with a few screws.
4. The radio must be put into a "Internal System Alignment Routine".
a. Attach the battery to the radio.
b. Turn the radio on whilst holding the 2 volume and squlech buttons
and the call buttons.
5. This will provide access to alinment menu which will alow you to ajust
these settings for each band. To select the setting you want to adjust
use the dial. To ajust the setting press the FM key until "F" blinks.
Once you are done adjusting the setting tap the FM key. This will save
the setting. once you are done with every thing, you must make all
changes permenient. To do this press the CALL key. The radio will power
off.
a. Band and IF
b. S-meter
c. Devation (low and High)
d. Squelch
I will describe each of these settings in apendix A.
6. All we need to do is adjust the Band edge setting for each band. The
setting for each band is "BAND 7". I have a partial list of the
different band layouts listed in apendix B.
a. First press the FM key and use the up and down keys to get the
display to read "BAND 7" on the VHF Side, press FM to save the
setting.
b. Press the band key to get to the other band
c. Press the FM key and use the up and down keys to get the
display to read "BAND 7" on the UHF Side, press FM to save the
setting.
d. Push the Call key to save all settings. The radio will turn off.
7. Turn the radio on. It should now tune from 60-999 MHz on each Band.
8. If all you wanted was the expanded recive with out 700-999 MHz, you are
done! If not, it time for the hard part.
Modifying the 440 board
In this seciton you will be installing some switching transistors on the 440
Mother Board. This involves very small smd parts. If you are not carful you
can messup your radio!
1. you will need the folling parts from yaesu:
PART TYPE YAESU P/N
C3082 -- 2 pF -------------- K22148206
C3089 -- 2 pF -------------- K22148206
C3090 -- 2 pF -------------- K22148206
c3091 -- 2 pF -------------- K22148206
C3108 -- .001 µF ----------- K22148820
L3021 -- .022 µH ----------- L1690381
L3030 -- .0068 µH ---------- L1690378
Q3031 -- 2SC4227-R32 ------- G3342277B
Q3032 -- 2SC4228-R42 ------- G3342287B
Q3038 -- 2SC4228-R42 ------- G3342287B
Q3039 -- 2SC4228-R42 ------- G3342287B
R3054 -- 33K --------------- J24189115
R3055 -- 33k --------------- J24189115
R3060 -- 1k ---------------- J24189119
R3066 -- 470 --------------- J24189111
R3071 -- 470 --------------- J24189111
2. Epose the 440 MHz board.
a. Remove the Knob and the lock nut from around the shaft. I find a
small screw driver to work well for this. If you have a spanner
wrench use it!
b. Remove the screw from in between the mic and speaker jacks.
c. Remove the 4 screws from the back metal pannel, and the 4 screws
from the plastic L cover over the back of the key pad.
d. Remove the battery release tab from the back, and the 2 screws
securing the L cover to the metal back cover.
e. Remove the front cover, beeing carful not to loose the gasket.
f. Release the flat ribbon cable from the Main Unit. Then angle the
Main unit upwards and pull it away from the radio.
g. Remove the contact unit (the small board that the ribon cable
goes into, that is pluged into the 144 and 440 units.) by
alternatly prying gently up on each coner of it with a small flat
screw driver.
h. Remove the 4 screws in shield over the 144 unit, and the 1 screw
that goes into the the board it self.
i. Lift the top shield, the 144 board, and the secont shield over the
440 board.
j. Remove the screw from the antenna connector, and lift the 440 unit
out of the radio.
2. Install these parts acordign to the parts layout diagram (fig 1)
3. Reassembile the radio.
4. Power the radio on, you should be able to recive 700-999 MHz now.
Notes on the preformance of the mod:
I have done this to my radio, S/N 5H132340, and it has worked just fine. The
sensitivity in not graet, but it works well enough to recive my local police
depattment on 856.2125. The step size is fixed to 12.5 kHz, but you can enter
any frequency you like on the keypad, and it will work. The shitty software
from R/T Sys will not alow you to program or edit any memory that has
700-999 programed into it!
I will take some Senitivity mesuremsnts and apend them to this mod sheet when
I get a chance.
Apindex A
INTERNAL SYSTEM ALINMENT
These adjustments are all done in software, if you want to change the
deviation, or the responce of the S-meter you can easly do it from the keypad.
The setting of each adjustment is seperate for each band.
1. Devation adjustment.
The radio will allow you to adjust the high and low gain seperatly,
which alows you to "customise" the transmit audio for you own voice.
The adjustment for the high frequencys is "MOD H" and the setting for
low frequencys is "MOD L". These can be adjusted with the up and down
keys. The factory says to adjust the radio to 4.2-4.5 kHz with a 25mV
1 kHz tone fed into it.
2. S-Meter
The adjustments that can be made here require the radio be recivning a
signal to set the adjustment, as it can not be adjusted with the up
and down keys, like the devation can be.
The "S-FULL" adjustment sets the amount of signal that would cause the
S-Meter to light fully. The factory says the amount of signal to
inject to the reciver, is +20dBµ with 1 kHz tone and 3.5 kHz devation.
The "S-1" adjustment sets the amount of signal that would cause the
very first unit to light on the S-meter. The factory says the amount
of signal to inject to the reciver, is -5dBµ with 1 kHz tone and 3.5
kHz devation.
3. Squelch
This setting adjusts the action of the squlech. (this is my
understanding) The Squelch circuit is a bi-leval acting squelch,
meanig that as long as a strong signal is being recived the squelch
will chop off imidelitly after losing a carior. When the signal is
weak, there is some hesterisias introduced into the circuit to prevent
it from chopping a weak signal.
The first adjustment, "SQL TH" will set the Threshold for a weak
signal. The factory setting is a -11dBµ signal. You can mess with
this if you want to, but it is best to leave it alone. if you do
write down your present settings first.
The second adjustment, "SQL TI" sets the signal level required to
cause the squlech to close at the end of a signal with out leaving a
burst of static (i.e. a squlech tail). This is set at -5dBµ from the
factory. This can also cause a signal that is very wide (5-6 kHz of
devation) to clip. If this hapens to you, but the signal sounds fine
when listing to it with the squelch open, this needs to be set to a
larger signal level. I have had to do this to my radio, as quite a
few hams have rich audio!
4. IF selection
I have no idea what this does other than setting the recive frequency
different from the displaed freq.
I have expermentied with this setting on vhf and found the following
off sets for the actual RX frequency vs. the displaed frequency.
IF # Offset (All in MHz)
1 +29.8
2 +27.8
3 +23.25
If you have any info on this at all please write me an email and let
me know.
Apendix B
Band setting
I have Exparimented with the BAND setting and have found the following limits
on vhf for the various settings of it.
Band # RX Range TX Range
0 60-180, 300-512 144-148
2 110-180 140-174
3 110-180 140-174
4 110-180 144-146
5 144-146 144-146
6 110-180 144-148
7 60-999 60-999
UHF
0 300-512, 700-999, 60-180 440-443
If you have any corrections/aditions to this please email me with them.
Apendix C
Settings of my radio (S/N 5H132340) from the factory.
Setting VHF UHF
Band 1 1
IF # 0 0
S-FULL BB 66
S-1 47 23
SQL TH 72 84
SQL TI 45 5D
MOD L 25 20
MOD H 27 24
This is a DRAFT verson of this document and may not be posted by any one,
to any place in cyberspace or published in any book with out my express
written concent.
Copyright
Bryan Fields, KB9MCI
KB9MCI@QSL.NET
(708)-862-3485
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