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IC-7800

Last update:  03/30/2007 09:09:27 -0700

The IC-7800 at WAØSXV.  To the left standing on its side is the USB keyboard.  On top of the radio is (l. to r.) the PW-1 amplifier controller and the homebrew SO2R controller.  The alligator clip and switches at the lower right are homebrew switching of the radio between control by the SO2R box or the PTT lines for digital software.  With the PRO that the 7800 replaced they also switched audio to the sound card but the 7800 has its own dedicated digital sound card.

The radio was installed at around 0100Z May 15th.  Comments to date are below.  These comments reflect version 1.20 of the software (software date 8/20/04).

NEWEST: 

DX4WIN

I have DX4WIN V6.03 working with the 7800 as radio 1 and the 756PRO as radio two.  To interface the 7800 I simply selected radio type of IC756PRO and entered 6A as the address.  Worked like a charm.  If you want a "RIG" file that will say ICOM 7800 and have the correct address, download ICOM 7800.rig here.  Put it into the DX4WIN "radios" directory and you can then select ICOM 7800 as your rig and support not only AM, SSB, RTTY, and CW but also PSK31!

Writelog

I configured WRITELOG for SO2R operation.  I was able to get it to recognize the 7800 by specifying that it was an Icom IC756PRO2 and making a somewhat hokey INI file entry to set the PRO2 CI-V address to 6A.  The existing PRO was put on another port.  Dual radio operation was confirmed and contacts made with both radios in the Anatolian RTTY contest.  Thanks AA5AU and W7WW for the Q's.

PW-1

Connecting to the PW-1 is simple although CAUTION -- the 7800 has higher output so you need to reset the PW-1 ALC level.  If you don't do this you'll get about 1,500 watts out of the PW-1 which presumably will decrease its life.  Set the PW-1 ALC level to minimum (full counter-clockwise) before you try it with the 7800.

Meter

People are bound to complain about the lack of an analog meter.  The analog meter simulation however is outstanding and it is easy to forget that you are seeing a computer simulation.  If it really upsets you to have the digital simulation of the analog there is a jack where you can connect whatever meter you wish.  Version 1.20 of the software has added the capability of setting the damping of the meter.

Sound Card

I purchased a S/P DIF USB sound card and optical cables to connect it to the 7800 so that I can evaluate that means of interfacing. This has posed some minor problems. More...

I'm happy to report that the S/P DIF works just fine.  I ended up with the 7800 output level at 38% and the Creative Mixer level at around 65%.  Also note that after all of the debate on how to plug in the cables to the Creative, on the IC-7800 the arrow is on the bottom -- not the top.

When copying RTTY using MMTTY I noticed that the decoder in the 7800 would show the station about ten hertz off frequency when MMTTY was right on.  I had visions of calibration or implementation problems in the 7800.  Fortunately I first did the sound card calibration procedure in MMTTY -- which is somewhat similar to the procedure used in MMSSTV.  Turns out that the sound card was considerably off.  In fact, to achieve the 11025 hz clock I had to set the sound card to 11101 hz.  I then tuned the 7800 to WWV AM and checked the soundcard frequency on the 440, 500, and 600 hz tones there.  The quick calibration got me with a fraction of a hertz so I quit.

MMTTY now agrees with the display on the 7800 so that particular gremlin has been chased down.

I did the same procedures with the Crystal Audio integrated sound card in the Dell PC.  It was within a few hertz.

I checked reception of SSTV using the digital sound card and it was essentially perfect without the need to calibrate MMSSTV.

Keyboard

I purchased an inexpensive USB keyboard and can report that it works fine for RTTY and PSK.  It also allows somewhat simpler entry of the CW message memories.

TCP/IP

I have connected the 7800 to the LAN.  The switch that it is connected to reports that it is capable of 100mb full duplex.  This is good as it means that the port auto-selects which is necessary since Icom did not provide a means of configuring the LAN mode.  The 7800 responds to "pings" and telnet but little else.   Icom really needs to document the 7800 IP interface in some way.  More info...

The LAN port offers an excellent high-speed method of loading software updates.

Spectrum scope

I have spent some time experimenting with the spectrum scope.  The 756 and the PRO both had a scope.  The scope on the PRO was a great improvement primarily because of greater sensitivity.  The 7800 scope seems somewhere between the 756 and the PRO in sensitivity.  But it has two features that really make it interesting.

First, it can be set to scan the entire band.  This is great to get an overall view of things.  The 7800 is set with the band edges for 160-6 (except 60m) and when you select the "CENTER" function you get the whole band.

Even more interesting is the very narrow scope scan range of ± 2.5 kHz.  This allows close examination of signals.  In addition, for SSB the scope is centered on the center of the receive passband, not the carrier frequency.  Very interesting to look at the USB "hi-fi" signals around 14.178 mHz.  The effects of boosting lows and the amount of transmitter energy used by those lows becomes very obvious.

I don't have a good dummy load here in Taos so haven't spent much time setting up my transmitted signal.  I'll get a load delivered here soon and then spend some time making sure that the result of all of my settings not only sounds good but represents appropriate parameters and bandwidth.

PSK31

Icom has touted the inclusion of PSK in the standard modes of the 7800.  There is an excellent PSK demodulator with the conventional vector tuning indicator and the waterfall.  When the signal is properly tuned the decoder seems to do as well as DigiPan or MixW running on a local PC with the fiber optic digital audio interface to the 7800.  The documentation does a fairly poor job of explaining use of the three tuning indicators.  This is probably in part due to the translation of the manual from Japanese.  There are numerous examples elsewhere in the manual of the same sort of translation problems.

The problem with PSK is actually two related problems.  The default tuning rate for CW, SSB, and PSK is 10 Hz. steps.  This is fine for CW and SSB but essentially useless for PSK.  Getting within 10 hz is inadequate for PSK.  So the first step in successful PSK tuning is to press and hold the "TS" button for one second.  This engages 1 hz tuning for not only the mode that you're using but for all modes.  This is a nuisance and poor user interface.

FIXED:  The following problem was fixed with the 1.20 upgrade which added AFC and NET options to PSK.  Makes a big difference.

The second PSK problem is the lack of any kind of AFC or "snap-to" tuning.  The 7800 has an "AUTO TUNE" button for CW and AM, but the button is not active for PSK.  So you have to select the 1 hz mode and then very carefully watch the vector indicator (the waterfall will only get you close) and get the signal "right on".  With time I suppose that I will get expert with this but compared to the point and click tuning of the PC-based decoders this is clumsy.  An effective limited-range AFC and "snap-to" function for PSK would be a welcome addition to the product.

Auto Tune.

There is a feature for AM and CW called AUTO TUNE.  It automatically tunes the signal in correctly.  This is very handy for AM as it will zero with the carrier.  For CW it does a fair job in tuning the signal to the correct pitch.  What is interesting (and is not in the documentation that I could find) is that AUTO TUNE normally  moves the VFO to center the frequency.  But if you have RIT engaged it will use the RIT to center the frequency.  I used this in the WPX CW contest during runs -- it does a good job of centering the selected station without changing the transmitted frequency.

Again though -- AUTO TUNE should have been implemented for FSK and PSK.

Bug list

I guess that the consequences of a software-defined radio are software issues, the good news being that these are minor and presumably can be patched via the network port.

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