Ham Radio LF to Microwaves

Packet, APRS and the ISS Space Station

2011-01-24T05:20:00.000-08:00

I have been away from Packet for a while :- Old hat, BBS's closing down and just a small population of Pipe Smoking, Wurthers Original sucking, Pullover wearers left.

I gave up with APRS too when everyman and his dog decided that he was gods gift to radio, digipeating, and Internet linking and jammed up the system.

This means I have also been away from checking the ISS packet activity too.

With old computers scrapped out I noted the other day that I had no packet capability now, time to take another look at the situation. I found APRS has changed totally, it is much less congested and the Internet linking seems well organised.
I then looked at the Space Station signals, they were strong on both my beam antenna and co-linear vertical. I then tried getting a signal into the APRS SGATE, that was not so easy with a few failed tries. Right then a challenge, I like those.

Today a couple of passes were in range at mid morning so I used about 20Watts to my 9 ele Tonna beam on 2 meters. Success, there are quite a few stations active to compete against, judging by the distances covered no doubt some pretty strong stations too, but I made it.

Just like Albert's mum and dad who had their son eaten by the lion and proved it by showing his cap, it is nice to go to the web and see proof with the data recorded there.

First thing the UK Map.

Next the Station list.

The Messages from ISS.

00:00:00:33 : IN3KLQ]CQ,RS0ISS-4*,qAR,OE3XUR::BLN0QSLs :RS0ISS-11,G3ZJO,RS0ISS-4,S51KV,HA3HT,DL6SDA,PD2RLD-8,EA6XQ-15,
00:00:00:43 : IN3KLQ]CQ,RS0ISS-4*,qAR,OE3XUR:=4617.32N/01130.40EyOpr.Giuliano in3klq@amsat.org {UISS41}
00:00:00:47 : RS0ISS-4]CQ,SGATE,qAR,OE3XUR:]ARISS - International Space Station (BBS/APRS on)
00:00:01:03 : YU7RD]APRS,RS0ISS-4*,qAR,OE3XUR:=4532.92N/01930.11E-Op.Vlado/BBS:YU7RD@9A0BBS.HRV.EU {UISS52}
00:00:01:23 : PD2RLD-8]APOT21,RS0ISS-4*,qAR,EI7IG:!/3Xe:OrW6- st - Roland - www.PD2RLD.nl -
00:00:01:28 : EA6XQ-15]APRS,RS0ISS-4*,qAR,ON7EQ-1:Hello To All! Software:UISS v5.2.6
00:00:01:29 : IN3KLQ]CQ,RS0ISS-4*,qAS,OE6PWE-2:73 frm Italy via ISS Giuliano in3klq@amsat.org
00:00:01:39 : G3ZJO]CQ,RS0ISS-4*,qAR,EI7IG::BLNQSL1/1:G3ZJO-6,G0BWC-3,S51KV,DL6SDA,DB3LA-6,PD2RLD-8,IN3KLQ{UISS52}
00:00:01:49 : IN3KLQ]CQ,RS0ISS-4*,qAR,EI7IG:=4617.32N/01130.40EyOpr.Giuliano in3klq@amsat.org {UISS41}
00:00:01:58 : IN3KLQ]CQ,RS0ISS-4*,qAS,OE6PWE-2::BLN0QSLs :RS0ISS-11,G3ZJO,RS0ISS-4,S51KV,HA3HT,DL6SDA,PD2RLD-8{UISS41}
00:00:02:03 : G3ZJO]CQ,RS0ISS-4*,qAS,OE6PWE-2:Hi All : UISS 5.2.6
00:00:02:09 : PD2RLD-8]APOT21,RS0ISS-4*,qAS,OE6PWE-2:!/3Xe:OrW6- st - Roland - www.PD2RLD.nl -
00:00:02:17 : DB3LA-6]ARISS,RS0ISS-4*,qAS,OE6PWE-2:=5132.92N/00649.38E`vy73 from Rhine-Ruhr-Area via ISS {UIV32N}
00:00:02:20 : DL6SDA]CQ,RS0ISS-4*,qAS,OE6PWE-2:=4906.27N/00907.71E- vy73 de Wolf DL6SDA
00:00:02:23 : HA3HT]4V1T21,RS0ISS-4*,WIDE,qAS,OE6PWE-2:'-1Sl -/]
00:00:02:48 : RS0ISS-4]CQ,SGATE,qAS,G7JVN-6:]ARISS - International Space Station (BBS/APRS on)
00:00:02:54 : G3ZJO]CQ,RS0ISS-4*,qAR,MM1PTT:=5216.60N/00054.39Wy73' Via ISS from Central England {UISS52}
00:00:03:17 : G0BWC-3]APRS,RS0ISS-4*,SGATE,WIDE2-2,qAS,G7JVN-6:]RIP John G1YYH-SK
00:00:03:18 : RS0ISS-11]DL6SDA,qAR,DH4LAR-10:Message:
00:00:03:39 : IK3ZGB-2]CQ,RS0ISS-4*,qAR,MB7UOD:=4542.75N/01142.00E`73' Via ISS de Cris {UISS52}
00:00:03:48 : DL6SDA]CQ,RS0ISS-4*,qAS,SM5SRR-1:=4906.27N/00907.71E- vy73 de Wolf DL6SDA
00:00:03:58 : DG4BR]APU25N,RS0ISS-4*,qAR,EI7IG:]240954zUI-View32 V2.03
00:00:04:05 : DB3LA-6]ARISS,RS0ISS-4*,qAR,EI7IG:=5132.92N/00649.38E`vy73 from Rhine-Ruhr-Area via ISS {UIV32N}
00:00:04:13 : MW0AQZ]APRS,RS0ISS-4*,qAS,SM5SRR-1::Heard :DG4BR,G0BWC-3,G3ZJO{UISS52}
00:00:04:27 : MW0AQZ]APRS,RS0ISS-4*,qAS,2E0XSD::G0BWC-3 :Healthy 2011 to all via ISS. 73 de Wyn qrz.com
00:00:04:31 : MW0AQZ]APRS,RS0ISS-4*,qAR,EI7IG:=5318.15N/00438.79W-fm IO73QH EU-124 Holy Island SH28 73 de Wyn {UISS52}
00:00:04:39 : G3ZJO]CQ,RS0ISS-4*,qAR,EI7IG:=5216.60N/00054.39Wy73' Via ISS from Central England {UISS52}
00:00:04:49 : RS0ISS-4]CQ,SGATE,qAR,MM1PTT:]ARISS - International Space Station (BBS/APRS on)
00:00:06:48 : RS0ISS-4]CQ,SGATE,qAR,MM1PTT:]ARISS - International Space Station (BBS/APRS on)
00:00:08:48 : RS0ISS-4]CQ,SGATE,qAR,VO1BIL:]ARISS - International Space Station (BBS/APRS on)
00:00:10:48 : RS0ISS-4]CQ,SGATE,qAR,VO1BIL:]ARISS - International Space Station (BBS/APRS on)
00:00:14:23 : N1NCB-7]43US5X,RS0ISS-4*,W3ADO-1,WIDE2-1,APRS,CQ,qAS,N1NAZ:`aS{l E/`USAFX.SEARCH & RESCUE.TEAM2-QSL_
00:00:19:49 : YV5JUT]APRS,RS0ISS-4*,qAR,YV5JUT-5:=1024.62N/06656.37W-Hi from Caracas via ISS {UISS52}

00:00:03:40 : SQ9MES]APRS,RS0ISS-4*,qAS,OE6PWE-2:Hello from Olkusz via ISS Op. Mariusz http://gumisiorek.blogspot.com
00:00:04:01 : G3ZJO]CQ,RS0ISS-4*,qAR,OE3XUR::EMAIL :g3zjo@npton.plus.com
00:00:04:07 : DM2FDO]CQ,RS0ISS-4*,qAR,ON7EQ-1:=5223.48N/01334.65E-73 de Horst www.qslnet.de/dm2fdo {UISS52}

I then copied my own on screen sent signals and received digipeated signals from the ISS.

So there we have it, lots of stations heard via the ISS and I was heard by lots too, I am not bothered with thinking about calling any a QSO, there must be enough information there to qualify for a few. I am just happy to have made it in again.

Now then where is this Nano sailboat satellite thingy.

Receive Loop Antenna for 500kHz

2010-02-16T00:18:00.000-08:00

I have good receive results on 500kHz, using my 40m Doublet with feeder strapped and no ATU I have copied the USA WSPR stations when only one other UK station was Spotting them also.
My TX antenna works well for RX too, yet with much discussion and some good results being reported using Indoor Loops I decided to try one.
I find one major problem when used indoors, despite the fact that the Loop can be oriented to reduce the pick up of interference from my Computer Monitor in the same room, the QRM from the Neighbour's Panasonic Plasma TV is severe and makes the band completely un-usable.

I hated the whole concept of Plasma TV's before one moved nearby. Despite the fact that I have many Panasonic Goods, I now despise that company for producing such poor equipment. In most cases of Plasma QRM it is Panasonic to blame.

In this wonderful enlightened age, the 42 inch Plasma TV is used in conjunction with a Dummy in the mouth of pre school children to rear and educate them with ranting American Cartoons on the Cartoon Channel. When the bleary eyed child decides he must sleep, the family continue to watch until the early hours. Therefore the QRM can seem to be 24/7 at times.

Other than that the Loop performance is impressive. I designed mine with 8 turns of 48 strand Litz wire spaced 10mm on a wooden frame.

It is tuned with a salvaged 3 Gang 500pF tuning capacitor. Coupling is by means of a toroid, just visible on the bottom mid turn in the picture below.

On a short test before the Loop was optimised, when the Child Rearer was off, I Spotted PA0A on WSPR in the daytime.

Transceivers RX Performance on the 600m Band

2010-02-05T11:42:00.000-08:00

I have been confused since my very first listening sessions on 500kHz by the carrier at the top of our allocation on 504kHz. Most screen captures and On-line Grabbers show this at varying strengths.
My Kenwood TS870 shows very little of the carrier using a long wire antenna, using my tuned 600m TX antenna on RX there is no sign of the signal.

Finally I have conducted some comparison test with the Kenwood TS870, Yaesu FT897, and Icom IC706. The screen shots show the three rigs using my 40m Doublet antenna with a Ferrite Slab coil in series roughly tuned to 500kHz. The pictures can be viewed full size by, right click on picture -view image

First the FT897. (the wide near vertical lines are from my LCD monitor)
The 504kHz carrier shows red.
Many odd wide horizontal lines are evident.
Reception of in band WSPR signals is good

Next the TS870, same antenna, no carrier on 504kHz, no horizontal crud. (again he wide, near vertical lines are from the LCD monitor) In band WSPR signals are good, maybe a dB or so up on the small rigs.

The IC706 MK nothing same antenna.(the monitor crud is almost horizontal)
The 504kHz carrier is bright green.
There are wide horizontal crud lines, not strong.
in band WSPR signals are good.

The IC706 again to prove a point. First half of the display is with the Doublet, second half is with the tuned 600m TX antenna. In band WSPR signals are stronger using the purpose 600m antenna, the 504kHz carrier is reduced.

My conclusions are that contrary to popular belief there is no radiated harmonic on 504kHz, it is a mixer product generated within the receiver, particularly the small portable toy rigs.

The short wide horizontal noise lines also experienced on these rigs are mixer products too.

As a final test I tuned my doublet to 252kHz and fed the TS870 with the signal.
Looks familiar the rig can be forced into the same poor performance as the toys.

The wide crud lines have a similar frequency distribution as seen in many screen shots.

Short Distance 500kHz Success

2010-01-28T10:29:00.000-08:00

After a bit of discussion on 70 cm this morning, we talked through Spectran and WSPR settings and use. I was convinced that any wire antenna in an FT817 would produce some signals on 500kHz. With 6Km between us G3KAN had just got to see more than just a 30 second burst of my QRSS.

At 14.22 we made it, using just the wire in the rig, the signal -15dB.

2010-01-2814:42

G3ZJO

0.503820

-15

IO92ng

+17

0.050

G3KAN

IO92

A run of 4 Spots followed, then some screen shots by e-mail. It will be interesting to find out how long the RX was on for when we talk again. I am intrigued by the possibility that short periods of enhanced propagation bring signals up to a usable level on a poor antenna at short range.

Activity on 500kHz Increasing

2010-01-28T00:42:00.000-08:00

500kHz (600m) Activity is increasing slowly as more stations in more countries get active. Once your Antenna efficiency RX or TX reaches a certain level the circle of possible contacts expands. The number of of stations logged quickly get to a level and new ones are slow to come in.

I am pleased to have a report overnight from the POLICE, well the call always looks like that and makes it memorable, I think, let me try, PA0LCE, yes that's right at 423Km and -33dB on WSPR so right on the edge of de-code-ability.

There are several more bridges to cross. Local stations at 5 to 6 Km and 15 Km who report, no see, although there may have been an odd 30 seconds of good signal at 6Km the other night, not enough QRSS to be sure. These local distances intrigue me.

500kHz QRP Sucessful Station

2010-01-27T11:51:00.000-08:00

After much experimentation I have settled on a set up for 500kHz that is giving me some good success.

The Antenna is an Inverted L, 6m Vertical and 8m Horizontal. The more Top Loading wire the better, however I don't have the space for several top wires. I added a lumped capacitance in the form of a disk 270mm dia and wire spokes.

The Loading coil is quite a large diameter wound with Silver Plated PTFE Insulated wire.

The PNP NPN pair PA produces some 500 or 600mW of RF at 50 Ohms. This gives an ERP of 200 to 275uW.

Results mainly using WSPR has brought reports from 32 different stations in 7 Countries.

Some preliminary results on 500kHz with Litz Loading Coil

2009-12-12T02:11:00.000-08:00

It is early days yet and only one station that is known to receive me, G7NKS has been active.
G7NKS is equidistant from G3ZJO and G3XBM and at reciprocal angles.

This is useful in theory. Previously I had compared the only available reports from signals not received at precisely the same time, this one is from 06:16 this morning thanks to WSPR net.

2009-12-12 06:16 G3ZJO 0.503810 -24 0 IO92ng 0.05 G7NKS IO92ub 46 120
2009-12-12 06:16 G3XBM 0.503865 -6 0 JO02dg 0.001 G7NKS IO92ub 46 240

Indicated Power levels should be disregarded G3XBM quotes an Estimated Radiated Power, I quote a QRPp Input, neither can be taken as exact. G3XBM runs 5Watts of RF, I run 160mW, this is 15dB less. The signal at G7NKS shows 18dB difference. I shall work more on my Antenna to see if I can eliminate the 3dB now apparent.

Litz wire for 500kHz Loading Coils

2009-12-11T13:52:00.000-08:00

After designing my 'pump' adjustable Ferrite coil for 500kHz I found a reference by Mitchell Lee to a Ferrite push rod arrangement. This really is quite similar to my set up.

The same write up mentions that Litz wire is good for an extra 6dB in some instances.

Litz now being rare, I wound a coil with 'home brew' Litz. Actually three enamelled copper wires twisted into a trifila winding, providing three times the surface area of an equivalent size single
wire.
Some of the coils I tried were less efficient, due I think to poor power transfer with link coupling, despite the match looking good. This time I used a tap coupling. The large coil is some 680uH and the small Ferrite rod adjustable one is 50uH when air cored.

The large coil is wound on a genuine Tupperware container a further larger container is inverted over the coil as a protective weather cover.

All coil formers are fitted with screw threads so that they are interchangeable for tests.

I adjust tuning for maximum RF field, sensed on a whip or maximum current on a small QRP meter.

Using a field strength meter it is immediately apparent when a good match is achieved.

The QRP current meter has a single turn on the centre wire, the current into a 50 Ohm load is indicated by the mid scale reading.

That tiny signal on 500Khz

2009-12-05T04:13:00.000-08:00

The next thing needed to get a signal on the 500KHz band is an Antenna. I removed several in my collection which I don't use much now, a WX Satellite Quadrahelix, a 10 Turn 23cm Helix, a 2.4GHz Dish and a 30m wire Dipole, in order to tidy up and dedicate a 6m mast to holding one end of my top span for 500KHz.

Even by Amateur standards my T or off centre Inverted L is small, a 6m Vertical copper wire is loaded by 10m of Horizontal. Increasing the number of wires in the Top Load would make an improvement to the signal but not to my state of embarrassment re my crowded Antenna Farm (Patch). No I think it has to stay as it is.

At the far end another 6m mast is used to support the Top Load and my 40m Doublet. In the photo the centre feed point can be seen and some high visibility beads on the wire which have all crowded toward the centre.

I measured the Antenna capacitance as 132 pF, an inductor of 751 uH is needed to tune this to resonance. This needs to be variable, Variometers are often used for this, I believe they are a bit of a lossy solution so I devised a method of 'dipping' a Ferrite Rod into the top of the coil rather like a bicycle pump arrangement. The test set up is shown here.

This turned out to be surprisingly efficient in some test arrangements but not good enough. One problem is the small wire diameter which adds losses. The other, mechanical, I mounted it too close to ground thus adding loading.

I have a large Racal glass fibre coil former, it's built like a tank and fully waterproof which has never really done an efficient job on HF. I had already re-wound it starting with 16g enamelled copper wire stepping down to 20g at the end this is 250 uH. I added a 4 turn coupling coil and SO239 Socket.

Instead of a screw in whip as is intended I added a threaded bush to my 'ferrite pump' coil to enable this to be screwed on top. This adjustable coil 41mm dia. wound using 1mm wire is 230 uH with no ferrite.

With Ferrite it can be adjusted up to as much as 900 uH. The 'pump' set up if fully waterproofed using plumbing goods.

It is a patch antenna, (cabbage patch) the Purple Sprouting Broccoli will get taller and will be gone next season.
I wonder if the closest plant does cause some loss, we will have to eat our way out of that one in the spring.

I really am that restricted for space, I shall continue to try for improvement but I think there is not a lot left to achieve judging from signal comparisons with other stations who run 5 watts.

I have definitely improved on my 40m Doublet with strapped feeders by 3dB using this antenna.

My signal has been spotted by 4 stations the most distant being G0KTN at 145Km

More results and comparisons another time.

500kHz QRPp

2009-12-04T15:43:00.000-08:00

I decided to try QRPp on 500KHz. I have run my Low Power MEPT's with WSPR on HF and VHF / UHF with good results.
I then developed the XORgan which uses 2 Crystals and an XOR mixer to produce WSPR code at Audio frequency for PC Less and thus lower power consumption WSPR.

The XORgan led me to try the Hypersonic XORgan using the same method to directly generate WSPR, QRSS and Hellschriber at a very very high Audio frequency :-) 500KHz in fact.

I added a one chip Buffer / PA stage so that in just 2 chips I have a complete LF Transmitter with an RF Otput of 160mW. Existing stations on 500kHz were geting good results using 5Watts from their TX's and WSPR. I reconned I could get usable results with my 160 mW (15dB less power) so that was the basis for my Experimental Permit.

Quite rightly some advice said that on LF if you have a little Antenna Loss it is no great problem as you can just use a little more power to compensate. On the RX side there is little need for a super efficient Antenna. At my QTH I dont have the possibility for a very good Antenna so I have to make the small set up I have as efficient as possible. With QRPp there is nothing available to waste.
Up to now results have been quite encouraging. Antenna tests continue, more on that and the results later.