ICOM-7851 musings

A friend has been having some issues with his new, rather gorgeous, ICOM flag ship radio, the IC-7851. CAT issues, com port issue, cw keying issues, STEPir tracking issues. This post is really to act as a record, and perhaps help anyone else with similar problems. All related to configuration, possible conflicts and other such annoying gremlins.

So, after removing the icom usb drivers, unplugging the usb cable, and reinstalling the drivers, then reconnecting the usb cable, the radio and computer seemed happy. COM7 and COM8 showed up in device manager. However, there does seem to be an issue where upon reboot, sometimes the USB devices will not be recognised. This issue is to be monitored and some more work perhaps required figuring out what is happening.

Moving on, we managed to get the radio talking to HRD and Logger32, at 19200 baud, 8n1, no handshaking, on COM7.

We then looked at CW keying over the USB cable, instead of running a separate cable and related serial interface. The IC-7851 presents two com ports as mentioned above, COM7 seemingly the CAT control, COM8 the keying port perhaps. Another friend did mention that COM8 might be second RX, but not entirely sure on that. Anyway, COM8 was used in the keying config of Logger32, and the 7851 was configured to use USB2 DTR as its CW keying source. All worked great, with CW and break-in selected on the radio.

We then looked into getting the STEPir auto tracking the vfo frequency. The STEPir control box is quite an old version, pre-dating the current SDA100’s. After much head scratching, we decided to use the remote (ci-v) port on the radio. The TIP of the 3.5mm jack, going to PIN9 (ttl rx) of the 9way d-type female that plugs into the STEPir box, and the RING to pin5 (gnd). A quick solder job and it was all working. Note: the pin out of the STEPir 9 way is not standard serial, certain pins are there to be connected to different makes of radios.

3.5mm mono – 9way d-type female – CI-V to STEPir

It has been noted that the STEPir will only track when the vfo on the radio is adjusted, and not when Logger32 tells the radio to move frequency. The IC-7851 needs to have CI-V transceive turned on.

Some configuration settings recorded here as a record.

73!

current IC-7851 settings

Tannoy Reveal 502 issue

So, one of my Tannoy Reveal 502 speakers kept blowing its T500mA fuse. I purchased some replacements, tried a new one, and pop. Something was obviously wrong.

The cabinet was a bit awkward to open, but I needed to get in there and have a look. The outer screws removed I poked something soft(ish) through the front port and ‘persuaded’ the back panel to come loose.

After a quick visual inspection I noticed that C11, a 100nF decoupling? capacitor, looked very hot and burnt. I did a quick check at this point and sure enough there was a short somewhere on the +ve and -ve rails.

Out with the soldering iron, I removed C11 and C6. C11 disintegrated as it was being de-soldered, and was obviously defective. I also removed the two 3300uF caps and gave them a quick test, they seemed fine. With those two re-soldered as they were ok, I replaced C11 and C6 with some 104’s (100nF) ceramics, and ran some tests with a new fuse in place. All seemed to working fine, sounding great. I left C6 and C11 on long legs to move them into some free air to try and reduce the chance of over heating. The yellow ‘hot snot glue’ was a nightmare to remove and was more like epoxy.

I must say, the ‘psu’ board did not seem to be of high quality. It looked as if it had been put together on a Friday afternoon, caps at all sorts of angles, rectifier twisted, just shoddy workmanship. I didn’t remove the amplifier/filter board so I can’t comment on that.

Anyway, a simple fix and I once again have a right speaker ! Happy days.

MB7TR – SSTV repeater

We have a new local SSTV repeater, and as far as I know one of only two in the country. Classed as a ‘regenerative node’ it will relay/repeat a received image.

MB7TR is situated in Cwmbran, and maintained by MW0RPB (Peter). It operates on 144.500MHz using FM and outputs in the Martin1 sstv mode.

To get it to repeat your transmitted image, which incidentally can be transmitted in any SSTV mode, you need to do the following, all on 144.500MHz in FM :

  1. TX your CW ident (good practice)
  2. TX a 1750Hz tone burst for around 1-2 seconds and key off
  3. Listen and wait for MB7TR to reply with its CWid – this signifies it is ready to repeat
  4. TX your SSTV image
  5. Sit back and wait for your image to be repeated out

You can use your SSTV software of choice, MMSSTV being mine. It is working great, after a few teething problems Peter has ironed out all the gremlins. Give it a try, you never know who might reply !!

GB3VHF signals

Well after having the new 13ele tonna up for a couple of weeks I recently noticed a signal around 144.430Mhz. After some quick research I discovered it to be beacon GB3VHF which outputs a JT65B signal.

I can copy the beacon on the beam S5-S6 seemingly 24hrs a day, so quite a good path between us. SNR’s of -1dB to -2dB in WSJT-X are the norm. I decided to listen with the x510n collinear vertical and to my surprise I could decode it with varying snr’s.

I ran it from around 3am on the 21/05/18 through to mid day, recorded the results and plotted them. You can easily see that the SNR improved from around 6am through to around 8:30am.

SSTV from the ISS

An SSTV image from a pass of the ISS @ 14:23z today as part of the “Expedition 55 Interkosmos” mission. I didn’t get set up in time so only managed to get the end of the last transmitted image. ISS was over north France at the time, at about 250 miles up. 145.800MHz +- some doppler. SunSDR2 Pro and the X510n vertical. 30dB over 9 signal.

The next pass at 15:50z ish was going right overhead, so I was all set up for this one. The first image (with the green noise) was received over the middle of the Atlantic (amazing 800-1000 miles away?), the second when overhead here in S.Wales and the third when passing over the east side of Poland.

The last pass of today, around 17:30z resulted in the following two images. Signal strength on the last was around S5-S7 with qsb. 

Most of the time signals were around s9+10 or so, with very little qsb. I did notice some flutter/phasing/qsb on the final image as can be seen by the noise lines over the image.

Anyway that is all for now. I will put any new images below.

73 Richie.

The (call)sign of things to come?

So, I decided to have a dabble on JT65 last night, had a listen to the bands and opted for 17m.

The frequency was quite busy but I found a spot where I could call some CQ’s. 7X3WPL came back to me, but as you can see he failed to give me a report. In fact, he ended the contact with a 73 and then started calling CQ.

So this station did not give me a signal report (look at the times), and he then went about calling CQ. I double checked back through the call/band history and could not see his call sign. Unless there was some serious QSB or some sporadic propagation openings he was not on that frequency calling cq prior to me.

So, this morning, I checked QRZ, and unsurprisingly there was a QSL waiting for my approval from 7X3WPL.

Now, as I am only a year or so on the air with this callsign, I would have liked to have had that QSO confirmed and add Algeria to my country’s worked, but no, I refuse to add something that has been so obviously made incomplete. Why bother even operating and trying to make contacts if you cant even be bothered to send a report ?  Obviously it could be, and probably is, an operating mistake but to then call CQ as well ? As it happens according to QRZ he gave me a -14 report.

Is this a sign of things to come, with more and more automation, and the 59 73 mentality ? I read about the up and runs where the last you hear from a station is R-02.

Please for the love of god, if you are operating a slow as hell mode (5-6 mins per qso) then at least send a report and see the qso through to completion. I am slowly getting fed up of wasting my time.

73

MB7UNE and balloons – KK6PNN-5

I noticed ‘in old data’ a balloon had passed over the UK on the 4th of March. KK6PNN-5 seems to have been around the earth at least once on its journey so far. Intriguing indeed !

I had received quite a number of APRS packets from the balloon through MB7UNE-10 but the one shown in the image below being the most distant.

A quick google search revealed it was released from the University of California, San Diego, on the morning of 12/02/17. A near-space balloon with an APRS pico payload on SBS balloon with H2.

Some more details…. click here !

73