External Speakers on FT847

When operating a special event station it is useful if the visitors can hear the audio output of the radio, and it is also useful if the operator can wear headphones - because there is always chatter and other noise going on in these places. But, when you plug headphones into the Yeasu FT847 the loudspeaker is switched off, so no one else can hear.

I found a fairly easy way round this. There is a second audio output available on the rear of the radio which has a 200mV output level, that is independent of the Volume control on the front panel. This is on a stereo 3.5mm jack socket marked Data In/Out. It is intended for connecting a packet TNC, or other data-mode device to the radio, but the audio quality from this socket is good.

Red arrow shows the Data In/Out connector on the back of the radio.

 The output is about the right level to drive a pair of PC speakers, but there is a snag ... The audio out is on the ring of the jack and the tip is used for PTT and for audio in, so if you plug the stereo plug from the speakers into this socket the radio goes straight into TRANSMIT! This is because the input impedance of the speakers is sufficiently low to make the radio think that the "TNC" has selected transmit. So I made up a simple adaptor out of a plug and socket, wired as shown below ...

Do test the speakers with the radio on transmit before using them at the event, because PC speakers are notorious for being sensitive to RF fields and may demodulate your SSB transmissions in an unpleasant way! Fortunately the speakers lent to us by Chris, G6AFY, were of high quality and behaved very well.

So here is a picture of me operating GB8WW with my FT847 and the PC speakers plugged in the back, the stylish, wedge-shaped thing in the foreground. If you look carefully you can see the adaptor-lead plugged into the back of the radio.

The headphone volume is controlled by the AF gain control on the front of the rig and the PC speakers are controlled with their own volume control.

One of the criticisms of the FT847 is the "steppy" digital AF gain control on the rig, making it hard to get the right listening level - so using an external speaker on this audio output might be a way round this in the shack - so this adaptor might be useful for more than the occasional special event station.

Happy Operating, and 73
Hugh M0WYE

Headset adaptor for FT847

It is nice to have both hands free when using the Amateur Radio - especially when operating a Special Event station or contesting, because you can fill in the log, and fiddle with the radio controls while talking. And  ... your thumb gets tired using a fist mic!

With the popularity of gaming and Skype, some nice headphones with microphone booms are available quite cheaply. I bought one of these: "Gearhead" AU3700S Computer headsets for £10.91. This one has 3.5mm stereo jack plugs for the microphone and headphones. I noticed that quite a lot of the headsets now come with a USB plug, which presumably has a USB soundcard built in. Not much use if you want to connect to an old analogue wireless set! Make sure you get one with jacks.

The headset is actually terminated in a "four ring" jack plug, suitable for Apple devices (apparently) but comes with a Y adaptor with a separate plug for headphones and microphone.

To use the headset with a radio we need some kind of adaptor box. This will have socket(s) for the headset and leads to plug into the microphone and headphone sockets on the radio. It will have a Transmit/Receive switch or PTT button, and with supply a bias Voltage to drive the electret condensor element in the microphone.

So this is what I built. I decided to stick with the "Y" adaptor on the headset, because it means that the box becomes more versatile having separate sockets for mic and headphones. I wanted the box to be well screened because there maybe high RF fields around, so I used a diecast aluminium box, from Hammond Manufacturing (Pt. No. 27969PSLA) - it is one I picked up last year at a Radio Rally. I found some flexible 9-way screened cable - more conductors than needed but I doubled up the ground connections to try and keep the impedances low.

But we have to be careful not to introduce ground loops. There is the cable screen, there is the microphone ground, there is the headphone ground and there is the PTT ground, and really they should all be kept separate. Trouble is a lot of jack sockets have a metal fixing nut that connects the barrel of the jack to the metal box that they are mounted on.

Fortunately I found some inexpensive, 3.5mm Jack sockets on E-bay which have a single (8mm dia) hole fixing, but are completely insulated from the metal panel.

Gold-plated too!

The FT847 manual has a useful diagram showing the microphone connections. The headset connections are fairly standard - in fact there is an industry standard which specifies the microphone and speaker connections. On the microphone the tip carries the signal and should be capacitively coupled, the ring carries the bias Voltage which must be less than 5.5Volts and sourced from an impedance greater than 2.2 kilohms. I used a 10uF solid aluminium electrolytic capacitor and a 3k9 resistor for coupling and bias resistor. Seems to work well.
Here is a circuit - drawn on CAD as you can see :-)

The mic connector is viewed looking at the front-panel of the radio. So it is viewed from the solder-terminal side of the (female) microphone plug.

The "spare" pins on the mic connector are used for "up" and "down" buttons on the microphone - but I haven't used them here.

The headphone circuit is kept completely separate - partly because the radio offers the facility to listen to your own SSB transmissions, so we don't want any audio getting back into the microphone socket. I used RG58 for the interconnecting cable, as we only need a mono signal for the 'phones.

the TX/RX switch is just a bog-standard DPDT toggle switch.




So here are a couple of pictures of the "innerds".

 I have tywrapped the incoming cables to the body of the jack socket. There may be more elegant ways of strain-relieving the cable but this seems to work ok.

The big fat grey wire, is actually the braid from the multicore cable being soldered to a solder tag on the die-cast box. Might have been better if this was a shorter connection from an RF screening point of view, but hopefully it will keep HF frequencies out of the box.








The finished box looks like this:

On air reports have, so far, been favourable. One thing to note is that the output of the electret condensor mic is much higher than the standard fist mic supplied with the radio. I used a deviation meter to check the FM modulation level, and found that I had to reduce the FM microphone gain from 32 to 12 in the menu system. Menu 25 [FM-PSET]. I also went through the procedure for setting the SSB microphone gain - setting the meter on the rig to measure ALC using Menu 24 [TX-MTR]. Strangely the SSB mic gain is set close to where it usually is. The "Moni" feature on the radio is great for listening to your own input, you can set the Monitor Volume using menu 20 [MONI-VOL] - but unfortunately you can't monitor when using the speech processor as it uses the same circuitry!

So there you have it, a Bank-holiday-Monday headset to FT847 adaptor box.
73
Hugh M0WYE

Further notes: 

The 3.5mm Jack is an EST Part: Part no. MJ073H, from Ebay, here http://www.ebay.co.uk/itm/351607508978

8 pin microphone connector also from Ebay: http://www.ebay.co.uk/itm/111965139338
But found the thread on the locking ring was poorly made, and won't screw up on the socket - so I will have to change it ... a pigging nuisance!

Wider transmit range on FT847

Some years ago UK Radio Amateurs were permitted to use the upper part of the 40m band, 7.100 - 7.200MHz. Many older radios, sold in the UK, such as my FT847, restrict the transmit range to what was previously legal, 7.000 - 7.100 MHz. It is rather frustrating when you can hear QSOs or CQ calls, but when you press the transmit switch you get a "beep" and an error message. Doubly frustrating when you know the circuitry is quite capable to transmitting and radios sold in some territories, such as the USA, do cover that part of the band.

I wanted to use the radio during the forthcoming "Mills on the Air" special event station, GB8WW, and it seems that the 40m band is used a lot for Special Events, so full coverage would be essential.

"Widebanding" radios, modifying them to transmit at any frequency, is quite commonplace, but requires the operator to take great care not to transmit outside of the band where they are legally allowed to. With the FT847 there is a further complication. The radio covers VHF and UHF as well, and the programming links which set the TX limits also affect the repeater shifts and the radio's ability to transmit on the 70MHz VHF band.

Fortunately G1IVG has put a useful table on his website, here, which shows the different ranges available. The programming links are on the PCB next to the memory backup cell. You can see them, numbered from 1 to 6 in this picture.

 The links look like surface-mount resistors, but are actually "zero-ohm links", and can be replaced by blobs of solder or very short pieces of wire. You can see that links 1, 2, 5 and 6 are shorted and links 3 and 4 are open. (Always useful to take a photo before you make a modification so you have half a chance of putting it right if it doesn't work!).

Looking at G1IVG's table you can see that there are only two link settings where the radio has the 70MHz band, the first is the standard UK configuation that I have, and the second one has links 1,2 and 6 shorted and the others open.  The HF options are in the table below, and this link combination gives the HF bands in row 5.

5

1.800-2.000

3.500-4.000

7.000-7.500

10.000-10.500

14.000-14.500

18.000-18.500

21.000-21.500

24.500-25.000

28.000-30.000

50.000-52.000

70.000-70.500

All the HF bands, except topband and 10m, are made 500kHz wide - so one still has to be careful not to transmit out of band, but, the problem of the 40m band is certainly solved by this. It doesn't allow the radio to operate on the 60m band, but (at the moment) this doesn't interest me much.

The 2m and 70cm bands become very wide, 140 to 154 and 420 to 450 Mhz respectively, so again, some care will be needed when operating on VHF too.

Performing this mod wipes all the channel memories and any changes you may have made in the menu system (display brightness, channel steps etc.), I already had a list of all my channels, with the CTCSS frequencies, repeater offsets etc, but I went through the menu system and carefully recorded all the settings there too.

So... I chose the finest soldering iron bit, found my tweezers and strongest reading-glasses, and set to work. Instead of removing the link 5 completely, I turned it round, so that it is still attached to the ground pad. That makes it easier to undo the mod, or reuse the link on a different pad if I need to.

The photo at left shows link 5 under a magnifier.

The links are only read by the microprocessor at factory reset, so it is necessary to hold down the "lock" and "fast" keys when you power up the radio for the mod to take effect. This is why all the all the channel memories are erased.

I turned the power control down to minimum, attached dummy loads to all four antenna sockets and carefully explored the frequency ranges. I am pleased to report that the new transmit ranges seem to match up with those in the table.

The repeater offsets basically match up with the UK standard settings, except for 50MHz where the offset is 1MHz instead of 500kHz. This is configurable in the menu system. So it all seems quite promising, and the radio is "good to go" for Mills on the Air 2016.

73
Hugh M0WYE

ISS SSTV, Second Pass

Two part-pictures received on the 8:19pm pass.

 This one faded into the noise as the ISS dissappeared over the horizon ...

Very nice visual sighting, with the station coming within a few diameters of the Moon and then passing very close to Jupiter in the twilight sky.
73
Hugh

Slow Scan Television from the International Space Station

It was a nice surprise to get an SSTV picture from the ISS on its 6:43p.m. pass.

I think the Russian Cosmonauts are commemorating the first Amateur Radio contacts aboard the ISS by sending SSTV pictures like the one above. I was using the free MMSSTV software, with the 2 meter radio connected to the sound card input. But for some reason the software didn't automatically select the correct mode (PD180). Fortunately I had a little Olympus voice recorder recording the sound from the speaker, so I was able to feed that back into the sound card and get the picture above.
The data compression might account for some of the patterning on the picture.

The transmissions are on the usual downlink frequency of 145.800MHz. You can read about how to do it on the AMSAT website here. But you don't need anything more sophisticated than a scanning receiver speaker output connected to the sound card line input. I just use my normal "white stick" colinear antenna, but a 1/4 whip, or even a rubber duck should pick something up.

I use the Orbital Prediction Page on the AMSAT website to find out when the ISS is coming over.
73
Hugh

Anatomy of a Trifle

Two boxes of Trile Mix - Strawberry Flavour.

Some other ingredients.

Swiss roll, with jam and cream. Chop it up so everyone gets a bit.

Add the strawberry jelly. Put in the fridge to set.

Separate the peach slices from the liquid and chop them up a bit.

Peach slices on top of the jelly

Add lots of custard.

To be continued ... !

... Early next morning !

 Moroccan raspberries are actually a bit disappointing, some nice raspberry flavours, but little sweetness. Hopefully be ok with all the other sweet things in the mix.

Bon apertit and 73
Hugh M0WYE

Windows Vista Automatic Update Problems

Since fitting the SSD the computer is very quiet, so , one evening,  my attention was drawn to the sound of the fan whirring. An investigation with Windows Task Manager revealed that wuauserv was running. This is the Windows Automatic Update service. It was using 50% (one core) of the CPU. After an hour I got fed up with it and started Windows Update manually to see what was going on. It just sat on "checking for updates" ... And nothing happened for another hour.

So I gave up and disabled auto updates.

Looking on some computer forums, it seems that others have had issues with the wauaserv locking up. But if your auto-updates are broke there is not much chance of downloading an update to fix it.

On one forum I found "Windows Offline Update" was a solution, so I decided to try it for myself. It is not Microsoft, it is Open Source. It allows you to download all the updates for a particular version of Windows, and copy them onto, for example, a USB stick. Then you can install all the latest updates onto a machine which is not connected to the Internet. I was attracted to it because it gives a bit more control over the update process.

So I downloaded it from here:
http://www.wsusoffline.net/docs/

There is a very good tutorial about it by Eli The Computer Guy..
Here:https://www.youtube.com/watch?v=aXAOvbNJYyE
It is worth watching this before attempting to use the software.

I found there were 2.5 GB even without the Office 2007 updates, so be prepared for a big download. The software worked very well, with a Windows "front end" that has check-boxes to select what you want to download or install. When you have made a selection some sort of script starts in a "command line" style box. Each step of the process appears on the screen and is logged to a file.

Although I had expected the offline updater to use its own software, it actually seems to use Windows own routines for at least some of the work ... including the dreaded Wauaserv! And, when a line appeared on the screen saying something like "building I.D. list of required updates", nothing happened for a very long time ... nearly 2 hours, in fact. If it hadn't been for the additional message which said "this may take a long time, please be patient" I would have aborted the process. The updater found, and applied, 19 updates.

This kind of software would be ideal for a computer repair shop where many computers have to be updated. Also if you have to reinstall windows, it might be useful to have the complete set of updates on a DVD or memory key.

For myself, I need to learn "patience", when wauaserv " locked up" it was probably just halfway through checking what updates were needed. Will we reach a point when our computers can do nothing else but install updates all day long!

I will probably go back to using Windows Update, but do so manually, putting up with the red shield symbol and the nag messages at boot-up. It won't be long before Microsoft stop supporting Vista anyway.

73
Hugh M0WYE