Sunday 25 April 2010

Introducing Felix - the Station Cat

After all the recent discussion of dead mice, it seemed only natural to get a cat!

Let's be quite honest about this - I don't like cats. Principally because I am allergic to them (more precisely, I am allergic to most of them). What's more, in truth, I find most cat owners mildly irritating too!

Still, this time I decided to put aside my prejudices, make an exception and allow a cat into the shack...

The cat in question isn't the allergen mentioned above - rather a Computer Aided Transceiver ("CAT") interface for the new FT 817.

I started off experimenting with a fancy circuit, using a MAX232 chip and some opto-isolators (loosely based on OK2FJ's work) but I was getting nowhere in a hurry, so I abandoned all and went back to KISS principles.

Here's my final schematic, which derives power from either RTS or DTR on the PC's serial port (selected by jumpers) or from an external supply and retains optional RTS control for PTT (which I was using previously)...

I designed a PCB using the excellent Eagle CAD package...

and made a few PCBs using the toner transfer method...

Here's the final system (not yet had time for a box etc)...

I had to swallow hard and prise open the m0xpd wallet to buy an 8 pin mini Din (Maplin code JX06).

The CAT works a treat - I can use Ham Radio Deluxe to control the FT 817 ...

and I even tried DM780 to make some BPSK31 QSOs....

Not a bad afternoon's work.

Now for the boring legal bit: please don't copy my CAT - invent your own! Your rig, your computer, or both may be strongly allergic to my CAT - caveat plagiarius

...-.- de m0xpd

Saturday 24 April 2010

Dead Mouse puts m0xpd on the map

More fun and games with the (nearly) new FT817 and the "Dead Mouse" data interface...

I needed to learn something about packet (for an up-coming project, of which more later) and so I decided to give APRS a try.

Warning: I know less-than-nothing about APRS at the moment - so the story below isn't intended as a "How-to" description. Follow it at your peril!

I downloaded the AGW Packet Engine and UI-View32, got registered on UI-View and set everything rolling...

The AGW "packet Engine" provides an interface between a PC and a Terminal Node Controller or - more importantly - uses the soundcard of the PC to emulate a TNC. Here's the AGW Packet Engine Icons in the system tray (highlighted)...

UI-View is an APRS client, which generates valid APRS "messages" to send, via the Packet engine, to the Data input of the radio. Here's the UI-View interface, with m0xpd shown on the map (this fix of my qth is achieved locally - there is, at this stage, no need to be transmitting RF, as UI-View recognizes the message being generated by itself)...

The message I'm generating is seen below (captured by UI-View's "Terminal" window)...

It includes (as I understand it)...

  • the (system clock) time
  • my call
  • an "Unproto" destination address ("APU25N") which specifies APRS as the destination for my message AND the fact that it was generated by UI-View
  • some specification of the routing which (may) be used to get my message to APRS ("WIDE3-3")
  • The Unproto "Port" ("1")
  • My QTH lat/long ("5326.45N/00223.44W")
  • and a message ("Paul @ home")

Joyfully, once the modulation levels were set right, this message was indeed received and transmitted to APRS, such that I could see myself on

Even more joyfully, my transmission was relayed by MB7UWC, my own club's APRS iGate...

...which (according to is 7.7 miles from my QTH. Funny - it seems further than that when I drive to club meetings!

...-.- de m0xpd

Tuesday 20 April 2010

Rockin' all over the world

Forgive my child-like enthusiasm, dear reader, but I'm really pleased to see the latest spot maps of my over-night WSPR contacts on the FT 817 (30m, 2W, g5rv)...

Alaska, Greenland, South Dakota (not a million miles away from my old home in Wyoming), Puerto Rico, Uganda and Australia looks like a good catch to me.

It would be interesting to know to what extent the location of my spots is a reflection of my (essentially) figure-of-eight antenna directivity (the g5rv lies approximately North/South) or a reflection of the relatively low operator densities to the North and South of my qth.

...-.- de m0xpd

Monday 19 April 2010

The WSPR of Oz

Quick update: my FT 817 with the "Dead Mice" data cable is now whispering down to David, VK6DI, in New South Wales (VK2)...

It is on 30m and at 2 Watts (+33 dBm).

OK - so it is more of a shout than a whisper!

...-.- de m0xpd

Sunday 18 April 2010

Dead Mice in the Shack!

Well - not those kind of mice, obviously.

Having spent a king's ransom (in my terms) on a used FT817ND at the NARSA Rally in Blackpool, I was unwilling to squeeze any more shekels out of the m0xpd wallet for a data cable. What's worse, I was even reluctant to buy a new Mini-DIN plug to make one up (available at Maplins under code JX04E for the princely sum of £1.39).

Fortunately, these 6-way Mini-DIN plugs -

are used on computer mice so they litter the land, ready molded to a nice length of cable! All I had to do was check that the correct connections are available and find some dead mice...

The relevant connections are as follows...

PinPS/2 MouseFT 817 Data
1DataData In
4+5VData Out (9600)
5ClockData Out (1200)

The pins of the Mini-DIN plug are numbered as follows (in this drawing, we're looking at the female jack on the back of the FT 817)...

As you can see from the table above, there are two pins labelled as "reserved" in the PS2 Mouse connections - these might be "no connections" in a mouse cable. This won't be too much of a panic for me in the case of the squelch status line (pin 6), but having no ground connection certainly would be an issue! Fortunately, this pin is paralleled with the plug "shield" on the FT817, so even if there's no cable to the mini-DIN pin 2, there is likely to be one to the plug shield.

I found a few "dead mice" (actually, the XYL found them for me)...

and examined the cabling - fortunately, of two cables investigated (one an un-shielded 6-core and the other a shielded 4-core), both gave me access to the pins on the Mini-DIN plug I needed (see table above). I ended up using the un-shielded cable, as it was easier (don't tell anybody).

I made audio connections via phone sockets, which I mounted in a small Maplins box (code FK72), found lying in the junk bin...

Then for the tricky part - I needed to hook up the cable to the COM port of my shack PC to control the PTT. Unfortunately, I hadn't any DB9 female connectors (and certainly wasn't going to spend any money, having come this far). Fortunately, the XYL came to the rescue again - for, when I said "can you find me some dead mice", she found an old three-button serial mouse with a molded female 9-pin on the end! Checking the pins on a serial mouse revealed that I had access to the two pins on the connector I needed - Ground and RTS. Phew!

I intended to make the PTT control according to the design on Jim's 2e0jps website . Unfortunately, on trying it, it didn't work (the PTT was pulled low when the RTS was at logic 0 (-11 V)). So, I had to make a trivial modification (the addition of a diode!)...

This system works for me - if you choose to copy it, you do so at your own risk (as it is neither warranted nor implied to be fit for any purpose). I have enough trouble being responsible for my own actions - I certainly won't be responsible for yours!

Here's the final cable - I added a clamp-on ferrite near the rig end to keep RF where it is allowed to be...

I tried the cable using MultiPSK and BPSK31 and had an immediate qso with Anne, oz1agn - it seems to work fine!

The FT 817 nd is certainly living up to its billing as a "do anything" rig - the only frustration is the need for a Collins filter for CW, which will require the wallet to be dusted off again!

...-.- de m0xpd

Saturday 17 April 2010

IFT Vindication

Last week's hunt around the junkboxes at the NARSA Rally for IF Transformers with Roy, gm4vki, was fruitless - except for a single Denco IFT11/10.7 (which - although I can find no data on the 'net, doesn't measure as if it is a 455kHz unit). However, Roy spotted an old domestic radio chassis in the bring-and-buy section, which I snapped up for a fiver. I gave myself a twinge in the shoulder lugging it back to the car!

I've now stripped out the chassis...

which yielded a fine harvest - fully enough to justify both the fiver and the shoulder. Some of the parts are of 1940s vintage and the set carries no obvious makers name and evidence of a lot of repair/modification.

Amongst the goodies to be harvested were the main HT transformer and a nice choke (these gave me the shoulder problem!) and the reason Roy spotted and I purchased the chassis - two IF Transformers...

On robbing out the IFT's from the chassis, one of them spilled it's innards from the can (I was intending to be very careful in disassembling the IFTs - but it came apart in my hand - honest, gov!...

Readers should understand that this was the first kosher IFT I'd ever had in my hand - all previous units were my own homebrew efforts (Blogs passim)!

First thing to delight me was the spacing between the coils - which was the same, staggering wide-open space that had shocked and surprised me in the development of my own h/b trannies. I still find it amazing that there is such distance between the coils for "critical" coupling. Second delight came when I hooked up the units to my wobbulator.

The response of these commercial IFTs was really no better than my homebrew efforts...

The measurement suggested that these units were...

1) under-coupled
2) better than my efforts with coils wound on sewing-machine bobbins

but, joyfully,

3) not as good as my final units with coils made from axial chokes

I am delighted to conclude that my IFTs are not the Achilles' Heel of the not-so-superhet receiver project I once suspected they were!

...-.- de m0xpd

Monday 12 April 2010

Birthday in Blackpool

"Yesterday it was my birthday
hung one more year on the line
should be depressed, 'cos my life's a mess
but I'm havin' a good time..."
Paul Simon

Well - not the anniversary of my mother's great labour. Rather it was the 2nd anniversary of my entry into the world of Amateur Radio!

It all started way back in 2008, when I heard it is possible to receive and decode NAVTEX information with a SW radio and a computer. Being interested in both sailing and doing something (like receiving NAVTEX) on the cheap, I needed to look into it.

I found a website called Beaconworld...

in which Alan, g4tmv, described NAVTEX reception (amongst loads of other good stuff about dx-ing for beacons of various sorts).

My trouble was two-fold...
1) I hadn't any gear and didn't know what to get
2) I didn't know how to cut through all the radio jargon (I'm a professional engineer, with way too much education and a lot of experience of technical authoring, etc but - even with that familiarity with technical English - it was hard to penetrate the jargon).

I solved both these problems with an email to Alan, who kindly replied at length on the 16th March 2008, including the suggestion...

"There is the annual Radio Rally at Blackpool today (Sunday) at the Norbreck
Castle in Bispham, so if you fancy taking the family out for the day and you
are looking for a radio that is the place to see them in the flesh and get
the bargains, lots of radio dealers will be there from all over the country."

Having nothing better to do that day, I drove up to Blackpool for my first ever look into the mysterious world of Amateur Radio - the rest is history! I met Dave m0obw (now President of the RSGB) who put me in touch with the guys at the Warrington Club and - particularly - Albert G3ZHE, who helped me through the licensing process.

Yesterday, two years later, I was back at the Norbreck Castle Hotel for NARSA 2010 - my "2nd Birthday".

Now the Norbreck isn't the most prepossessing sort of place but it does have enough space to hold the largest one-day rally in the country. My club is a member of the Northern Amateur Radio Societies Association, which runs the event and many of my fellow Warrington Club members do service as stewards - but not myself (being too lazy). I elected to go as a fare-paying punter.

Yesterday's trip was important, as I had already decided to prize open the m0xpd wallet in order to get a new rig (I'll explain why in later posts). Suffice to say, such was the significance of the event that Paul, g1dva, felt moved to take a picture of the clouds of dust which accompanied the opening of my credit card case (not having enough folding stuff in the wallet)...

This excitement was caused by my purchase of a (very slightly) used FT817nd...

from the good folks at LAM Communications, shortly followed by a Walkabout Mark II...

from the Sandpiper stall.

I also had the great pleasure of meeting up with Roy, gm4vki, a fellow Paraset replicator, who helped me in the search for some IF transformers to replace those HB efforts in the not-so-superhet receiver (Blogs passim).

I must say I'm really impressed with the FT817 - but I haven't had much time to play with it yet (as I write, I'm in Lyon, where the French 2m band is as dead as a door nail).

All in all, a great celebration of my "birthday" - just waiting for the palpitations and light-headedness associated with spending money to die down!

...-.- de m0xpd

p.s. It seems that Alan is about to close Beaconworld - perhaps you should give it a quick visit while it is still there. Thanks for everything, Alan!

Monday 5 April 2010

Dragged, kicking and screaming, back to 1998

Decided to give PSK31 a try today, just to see...

I used the microphone input to my trusty old FT101ZD, having already made up an "interface" when I started to look at WSPR. Interface is too strong a work - it is really just a cable :-)

I downloaded MULTIPSK 4.17, which is a bit of an overkill just to try PSK31 - but it works and the price is right (for the limited version at least).

I decided to use the 40m band as I'd heard were the PSK31 community hangs out (just above the top of the CW segment - sometimes not too far above it!).

After learning to drive MultiPSK I soon had contact with Toni, SP3NNE, but was too green with MultiPSK to have a meaningful QSO. Later, I contacted Rob, m0rby, who pointed out that I was QSY-ing upward on every over. Rob suggested this might be due to my FT101, saying it was common with older rigs.

I was annoyed at first (sorry Rob), thinking he was suggesting the old girl was drifting! But then I realized it wasn't drift - it was Rx/Tx offset. For subsequent QSOs I learned to keep my transmit frequency fixed and chase any changes in the far end's freq made in response to my Tx offset. I should have carefully set up the RIT / Clarifier on the FT101 but life is just too short! (Actually, this was resolved another way - see the Update below).

Had some nice QSOs (esp Horst, DD9ZZ, in Limburg), but came to the conclusion that PSK31 isn't really for me - it doesn't have the "immediacy" of CW. Perhaps I'll persevere a little longer...


Just made an attenuator to put into the audio input (allowing some better input SNR) and noticed that the preselect tuning was a bit off - which seems to have got rid of my Tx offset (no idea why). Now having easier time with QSOs (esp with Christer, SA4AZC, Eigil, OZ3AAF and Hansi, DB7HH). As I said to Reiner, DL8LRZ/P, "This is fun - but not as much fun as CW".

...-.- de m0xpd

Saturday 3 April 2010

Kippers, "Macaroni" and a B2

Just back from a very nice week's holiday with the family in Whitby, where government anti-smoking regulations are impacting local traditional industries...

The sign, which reads "It is against the law to smoke in these premises", seems strangely at odds with the process described on Fortune's own website... "Smoking is a long-established method of preserving fish and Fortune’s have been producing smoked kippers and smoked fish from the same premises in Henrietta Street, Whitby for over 137 years using unchanged traditional methods which are passed down from one generation of the Fortune family to the next."

While we're on the subject of fish, I spent an enjoyable couple of hours at the Pickering Trout Lake. This is a strange mixture of the family fishing lakes you find in France and a more traditional English fly fishery. Fishing buzzers I was rewarded by four recently stocked juvenile trout around the pound-and-a-half stamp and two real fish (below) before the cold wind and rain got the better of me ...

A nice feature of Pickering Trout Lake is the North York Moors Railway line, which runs alongside the boundary fence - it is good to fish whilst watching trains hauled by an interesting array of steam locomotives pulling into and out of the Terminus a few yards from the lake.

The cheapskate radio enthusiast in me was pleased to find a copy of Gavin Weightman's interesting biography of Marconi on sale (60% off) at The Whitby Bookshop, which was a good read...

The treatment of rival innovators (Fleming, Armstrong, Fessenden, de Forest) is a bit dismissive - but this is a biography of Macaroni, so no more comment.

En route for home, we stopped off at the Eden Camp museum, where the temperatures inside the display huts reminded us how miserable it must have been for the PoWs incarcerated there!

There is a B2 tucked away in one of the displays (dimly lit, awkwardly positioned and, therefore, poorly captured by my iPhone)...

There's also an interesting collection of military communication equipment, some of which is seen here...

There's the usual WS19s, an AR88 (I embarrassed the family by saying "I've got one of those"), some interesting test gear and a collection of field telephones.

A good end to a very good week,

...-.- de m0xpd