Paul Metzger wrote:
>Hello all,
>
> Has anyone here, or does anyone here know of anyone who has
>successfully modified a Tait 800 Slimline to work on 20kHz steps? I
>have two of them and would like to use them on the 440 Amateur UHF band.
>
>Any help would be greatly appreciated !
>
>Paul Metzger
>K6EH
>
>
>
>
Paul,
As stated in an earlier reply, the T800 Series I radios work fine on 20
KHz channels. The only downside is you can not use the factory software
to generate the PROM code as it is limited to 12.5KHz channel steps. By
changing the reference divide ratio (R) you can use 10KHz channel steps
instead of 12.5KHz steps. I am currently using them on 20KHz channels at
three sites. If you are uncomfortable with the formulas, let me know the
channels you wish to use and I can supply a hex format file with the
channel info you need. You would then load the hex file into your EPROM
programmer and go from there.
The formulas for generating the hex values required are (hopefully this
will be readable once posted):
TX FREQ(MHz) = M * 0.64 + A * 0.01
RX FREQ(MHz) = M * 0.64 + A * 0.01 + 45
WORD 1 2 3 4 5 6 7 8
REG M M M A A R R R
BIT L 0 2 6 0 4 0 4 8
BIT M 1 5 9 3 6 3 7 10
| | | | | | | | M A
CH # | | | | | | | |
0 08 0E 0A 0E 00 0A 00 00 698 14 446.860 TX USING 10 KHZ STEPS
1 08 0E 0A 00 01 0A 00 00 698 16 446.880 TX USING 10 KHZ STEPS
0 00 0B 09 06 00 00 04 01 620 06 441.860 RX USING 10 KHZ STEPS
1 0C 0A 09 08 00 00 04 01 620 08 441.880 RX USING 10 KHZ STEPS
The synthesizer data for M, A, and R is stored in the right / lower 4
bit nibbles of each byte above.
446.860 TX using 10 KHz steps (R = 10 decimal = 0A hex)
R register = 10 decimal = 0A hex (sets 10 KHz TX channel spacing)
M register = 698 decimal = 2BA hex
lsb msb
0101110101 = 8H + B0H + 200H
1248124812
A register = 14 decimal = 0E hex
lsb msb
0111000 = EH + 0H
1248124
To calculate the desired code for 446.86 TX:
446.86 / 0.64 = 698.21875 (the integer portion 698 is the M code)
698 * 0.64 = 446.72
446.86 - 446.72 = 0.14
140 KHz / 10KHz = 14 (the A code is 14)
Hopefully that makes sense.
Ed Yoho
WA6RQD
