The next step in our
search for luxurious operating is to replace the manual
selector switch with an automatic one. Again, these are
available commercially, and yet again my Scottish ancestors
whisper.. "Nay laddie..! Keep yer brass in yer pocket,
an build one yersel'... "
Commercial units can be found at ON4AOI,
Ten Devices , Dunestar
Systems , and
probably others that I'm not aware of.
To build a Band Decoder to drive our remote
relays, we need to supply the band information from the rig
to the decoder. Problems now arise, in that Kenwood don't
have this facility at all, ICOM provide this data in the form
of a set voltage value for each band, and YAESU provide the
data in the form of a Binary Coded Decimal (BCD) output to a
socket on the back of the rig. Interfaces can be built for
the ICOM and YAESU rigs, But how about KENWOOD??. Fear
not...fellow convicts...Help is at hand..!!!
Extremely clever people, who write nice
logging software for us dimwits have come up with a
solution... In their wisdom, they have decided that YAESU
have the best system, so they have written their software to
emulate a YAESU rig. In other words, if you connect any brand
of rig to your computer, this software can put the BCD band
information out to the printer port of your PC, in exactly
the same format as it appears on the back of a YAESU
rig....Devilishly cunning eh..??
Two logging programs that I know have this
facility are CT (K1EA) and DX4WIN. There are probably many
others that I'm not aware of.
complete ON4AOI pcb)
Thanks to the generosity of people like Bob
K6XX and Guy ON4AOI I didn't have to design one for myself, as they had
done all the clever stuff for me... The K6XX decoder is
extremely simple, just using a TTL chip, and a handfull of
discrete components. Bob
has a lot of nice usefull things
that you can homebrew. I incorporated his PTT amplifier on my own Band
decoder PCB, which tidies things up nicely. I used good
"beefy" switching transistors, and it'll probably key the national
decoder has now gone commercial. I built an
early design of Guy's. He originally gave all the details on his webpage. He
has now updated the design, and is selling it commercially. It is a very
comprehensive design with ten outputs. It uses buffering of the input, and
opto-isolators on the output, so it is a very safe unit. By
"safe"...I mean that your rig is protected from any
"nasties" coming back to the rig from the outside World...It can control a
bandpass filter unit (such as the Dunestar) as well as the antenna switch.
You can also arrange the switch to control combinations of bands.. For
instance, if you are using a tribander, the decoder can be programmed to
select the same antenna for the three bands. As with all the good
decoders, it'll happily work with Yaesu or Icom rigs and the usual logging
programs that can output band data to the LPT port.. Writelog, DX4WIN, CT,
Trlog etc. Guy supplies the decoder in various combinations, from a bare PCB, to a fully
boxed unit with all the "add-ons".
Amongst the goodies on
W9XT's site, I found another band decoder. It is a
complete PCB, and can control 10 antennae. I recently bought one of these,
and on examination of
the PCB, I see that Gary also uses opto-isolators in his
design. This appears to be a nice inexpensive option for the
guy who wants to supply his own box, or incorporate it into his own station
control box, SO2R or whatever.
Steve Wilson G3VMW
has done just that, using the W9XT board, to which he has added his own
source drivers, using BD140 transistors. We both reckon that this approach
is safer than using current sink drivers.
Decoder. W9XT board top RHS, PSU on LHS, Source drivers in centre.
Front view of Steve's decoder... Sexy
artwork! On top of the Switch box is his homebrew Antenna Switch
Box using the Far Circuits PCB for
the KO4NR Antenna Switch published in the April 2005 QST.
Pic of my completed band decoder. It uses the ON4AOI pcb)
I built Guy ON4AOI's original design. It worked
first go, with no problems. I cased it in an old external
modem case, which had a 12/24Volt DC power supply already in
it. I just stripped out the old modem PCB and made a new
front panel to hold the LEDs, rotary switch etc. It has a DB9
socket on the back to take the input from my FT1000MP, or
from a PC printer port, and a pair of DB25 sockets to drive
the remote relay box, and a DUNESTAR Band Pass Filter unit
(at the same time). I resprayed the box, and I think it looks
another beautifully finished unit, made by Akira JA1EOD