[aprssig] Re: Remote HF SkyCommand on the air

Stephen H. Smith wa8lmf2 at aol.com
Sat Feb 24 16:32:19 CST 2007

bruninga at usna.edu wrote:
> Our SkyCommand remote base is now on the air:
> http://www.ew.usna.edu/~bruninga/USNAremoteHF.html

I started playing around with remote HF control about 20 years ago with 
an ACC "Shackmaster" and a Kenwood TS-940.   The Shackmaster is a 
dedicated Z-80 based controller that accepts DTMF commands on VHF and 
communicates with the Kenwood via it's serial port.  It actually 
exceeded the functionality of SkyCommand in that it could also control 
the VHF/UHF rigs of the day that used BCD thumbwheel frequency controls, 
activate and read back the heading of antenna rotators, read the S-meter 
of the HF rig, do X-10 household remote control, and a lot more. (I used 
the X-10 to turn the AC power on to the HF rig.)

One feature that (to me at least) was always an issue was how to 
remotely select HF antennas,  and how to trigger the tune cycle of 
automatic antenna tuners.  

The Kenwood transceiver had a front-panel "TUNE" button that would start 
either it's internal tuner or an external coupler.  The problem was that 
there was no serial port command to remotely trigger the tune process. I 
finally would up connecting an opto-isolator's output across the front 
panel "TUNE" button's contacts, and used one of the general-purpose 
single-bit outputs (similar to a KPC3's) accessible with a DTMF code 
that the Shackmaster provided, to remotely "push it". 

Later, when the SGC 230 Smartuner arrived on the scene, things got 
vastly simpler. Unlike any other automatic couplers, Smartuners don't 
require any kind of tune cycle or handshaking.  You just provide 12VDC 
power and dump RF into them at any power level from 5-150 watts and they 
tune. The first time on a given band or freq they make take 10-15 
seconds to tune but they memorize the settings. The next time on the 
same freq, they will re-channel in less than a second. You just whistle 
on SSB for a second or so and the wire is tuned!   

[All other autocouplers I  have played with use handshaking tune cycles 
that command the radio to key up at reduced power (typically 10W CW) and 
then pull in a 10-20 dB pad so that the radio's finals see a constant 50 
ohms, and the relay contacts see only .1 to 1W while switching.  When 
the tuner's SWR sensor sees the magic 50+j0 condition, the tuner unkeys 
the radio, switches out the pad, and restores the radio to full power in 
whatever mode it was in before.]

I was always amazed that SGC got away with the rapid-fire hot-switching 
of relays (used to short and unshort sections of coil and to select 
various values of capacitors in the L-network) with up to 100 watts of 
RF on them without frying the contacts but somehow they do.

I notice that the SkyCommand menu conspicuously lacks a menu choice to 
function the "TUNE" button on the 2000's front panel that triggers the 
tune cycle of either the internal limited-range "line-flattener" tuner 
or an external coupler that plugs into a 6-pin Molex jack on the rear 

How are you going to tune/match the slopers:
      Fixed networks?  
     SGC "just dump RF into them with no control/handshaking 

And select one of the three (or antennas for other bands):
      Single contact outputs on a KPC3 with packets sent separately from 
      An external decoder responding to DTMF from the mobile mic? 

On the text file linked from the URL above, you seem are citing a path 
to a file apparently on your LAN.


Doesn't do us much good out here on the Internet.......


Stephen H. Smith    wa8lmf (at) aol.com
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