K9EQ AH-4 Universal Interface
Rev. 5
Page 5
www.hamoperator.com
2. If you are not in SSB or have not connected the audio interface, change the mode to one that emits a carrier (AM,
FM, or CW) and adjust the power output to about 10 watts (5 – 15 watts will work). (If you are in SSB, you will
need to turn off speech processing.)
3. Push the TUNE button. The AH-4 will automatically tune. A status light indicates that the AH-4 is tuning and the
final tune status.
4. Reset the rig’s mode/power (if it was changed) and begin operating. Note that any many cases it is only necessary to
retune when changing bands.
To be compatible with the K9EQ Universal AH-4 Interface, the HF rig should have:
o
A convenient means of adjusting output power.
o
Availability of a mode that emits a carrier (AM, FM, or CW)
o
A keying line that operates at a maximum of +20 volts and 100 ma. (The interface will pull this line to ground when it needs
to key the transmitter.)
o
The radio generates a 1 KHz tone when tuning. This allows the use of SSB modes. If the speech processor is turned off, it
may not be necessary to adjust power output when tuning. (Note that this feature may or may not work reliably depending
upon how stable the rig’s output is for a given audio level.)
Full Interface
The full interface adds the following features to the basic interface:
o
The interface generates an adjustable negative ALC voltage. This reduces the transmitter’s output when tuning. (Note that
this feature could require frequent adjustment since the radio’s characteristics may change with temperature and voltage.)
o
An RS-232 interface that allows computer-based rig control and logging programs to interface with the radio. The interface
can be used with Icom and Yaesu radios. (Kenwood should work also but has not been tested.)
o
The RS-232 interface will key the radio when DTR is asserted. This allows a computer sound-card based program, like
Digipan, to key the radio.
o
A computer sound card – radio interface has been implemented. This allows SSTV, RTTY, CW, PSK31, and other sound
card-based software to work with the radio.
For more information, please visit
www.hamoperator.com
. I am always interested in hearing your comments about this manual, the
interface, the AH-4, or any subject you care to discuss.
73’s,
Chris, K9EQ
Construction
The K9EQ AH-4 Universal Interface may be built using prototype construction techniques or by using the printed circuit board. These
assembly instructions assume that you are using the printed circuit board Rev. 2.
Construction options:
The board may be built with the one of the following three options:
