[ICOM] ICOM H6 programming help

[Gary Fiber]

Hi Reed,

I know its been over a month since we started this. I looked at the 
programming a few times. I used to be pretty good at H6 programming but I 
can't come up with a nice value of " N " using 37.305 for X-203.
What should happen is as follows.

" Value of N " = (Desired Frequency - Local Oscillator Frequency / 
.005)  -1000.
The .005 comes from the fact as you can program the H6 in 5 kHz increments.
So your H6 has a X203 of 37.305 MHz. X 4 = 149.216 = Local Oscillator 
Frequency.
Channel 1 has 158.865 - 149.216 / .005 - 1000 = 929.8,  according to the 
formula it can't work as there is no way to program a .8 value of N.

I thought maybe the X203 frequency was a bit different than you wrote so I 
tried a X203 of 37.30375 x 4 = 154.215
So i tried Channel 1 again 158.865 - 154.215 / .005 -1000 does not work 
either I end up with -70 as a value of N.

The H6 simplified programming information I got form Icom says forget the 
-1000 part of the formula
So the new formula is "Value of N " =  158.865 - 154.215 / .005 =N 930, 
that will work as it is an even number.
where 158.865 is the desired frequency.
I calculated out the frequencies that you posted from your H6 and this 
formula works out for every one.

Now the fly in the ointment.

If on the PLL board you remove R249 the whole frequency coverage drops by 5 
MHz and you get about 10 MHz range from the H6.
so the constant of 154.215 would now be 149.215
158.865 - 149.215 / .005 = 1930. Ah a value of N over 1000. Well a value of 
N 800 and N 200 don't add up to N 1000.
To accomplish this you will need to bring a wire from Pin 15 of the 9122 
chip to the matrix board for a line of N = 1000.
I seem to remember that Pin 16 was N 2000.
To use both N 1000 and N 2000 you would add a wire to each respective pin 
and bring that line to the matrix board.  You could bring it through a 
diode to remove a resistor feeding an unused line and attach it there for a 
cleaner matrix board. Sometimes you had no choice as every line of N was 
used during programming. Then the final result looked like a kludge with 
the extra wires and diodes feeding the N 1000 and / or 2000 to the channel 
that required it.

If you send me your postal mailing address I will send you what I collected 
at Icom. also it would be helpful to know the actual value of " N " 
programmed into one of the channels. Then you can work backwards to see how 
the odd ball crystal frequency fits in. the service manual says the range 
of operation between the lowest and highest capable transmitter frequency 
was 2 MHz up to 5 MHz with reduced specification.

I hope this helps a bit with your H6.

Gary K8IZ