This may be old news to many but perhaps will save a few hours of frustration for newcomers.
In my prior post about HRD Sat Tracking slowness with my Windows Vista computer, I reported there that ST was working very slowly with my Lenovo desktop running Windows Vista, but that it ran at normal speed with a laptop running Windows XP. However, the frequencies were not tracking properly -- the transmit frequency would "stick" as the receive frequency on my IC-7000.
It seems there is a hardware cause for this issue. After I gave up trying to get HRD Sat Tracking to work with the laptop, I downloaded SatPC32, another program that automatically sets transmit and receive frequency to account for doppler. The same "sticking" problem occurred with that program.
The ReadMe(Icom) in SatPC32 provides what appears to be an explanation for this issue: ************************** With ICOM half duplex transceivers (IC-706MKIIG, IC-7000) hardware handshaking must be installed to suspend computer control while the radio is transmitting. Frequency changes are theoretically possible while the radio is transmitting, but frequency errors will occur, i.e., the frequencies of VFO A and VFO B will be exchanged.
Unfortunately there is no way to check the PTT state of the radio via the CAT software. Therefore hardware handshaking is needed to prevent writing to the radio while it is transmitting. On the radio side pin 7 of the ACC socket can be used for this purpose. The voltage at this pin is approximately + 8.0 V while the radio is in RX mode. In TX mode the voltage at pin 7 drops to 0.
Pin 7 of the ACC socket must be connected with the CTS pin of the serial port on the PC side (pin 8 of the 9-pin, pin 5 of the 25-pin RS232 cable connector). I have connected these pins via a diode and a 5K resistor, see Acc_Com.jpg in this sub folder.
IT GOES WITHOUT SAYING THAT EVERYONE INSTALLS THIS LINE AT HIS OWN RISK!
When the radio pulls down the voltage at pin 7 to 0, it signals the PC not to send data. As soon as the radio is back in RX mode the frequencies are updated by the program.
ATTENTION! There must be NO bridge between pins 7 and 8 of the 9-pin (5 and 4 of the 25-pin) cable connector at the PC side! Otherwise the voltage at Pin 8 (rsp.Pin 5) and therefore also at Pin 7 of the ACC socket will be pulled down and the radio will be switched into transmit mode. The sketches in the Icom sub folder provide this bridge. If it is built in, please, remove it.
The 25-pin Connector at the ICOM CT-17 also provides a bridge between pins 4 and 5 and other pins. The CTS pin of the cable connector at the PC side must be connected only to Pin 7 of the ACC socket. ************************* Thus, as I appreciate this, a standard ICOM CT-17 CAT cable will not work properly with SatPC32, and presumably not with HRD Sat Tracking either.
Can anyone confirm this? Does anyone sell modified CT-17 cables that will do the job?
73, Bill NZ5N