Tuesday, 31 December 2013

Best 430MHz Antenna?

http://www.radiogearpro.com/main/product_info.php?manufacturers_id=12&products_id=673&osCsid=qsjfexubq

For everyday mobile use, this small 40cm antenna, Nagoya NL-77B has been the best on 430MHz. Compared to both a 1.5m long Watson dual bander and a 1m long W770 copy.
The bigger antennas are probably better when in a good location but driving round town, they don't have any more gain.
On 145MHz the gain is about -2dB relative to a 1/4 wave.

Saturday, 28 December 2013

A99 Finally Snapped

The the fibreglass on the A99 completely snapped last night, which I was hoping would happen as for the last 3 weeks it was swinging around bashing the roof. The wire inside is still connected so it will keep working as a kind of inverted V.

Sunday, 8 December 2013

Wind

Antron 99 snapped in last week's high winds. SWR still normal, signal not as good for local stuff but for everything else I don't think I'd have even noticed.

Saturday, 14 September 2013

Homeplug

I'm using a pair of Vesenet NET-PLA-14-E power line networking adaptors to link my Sky box to the internet. I'm planning to do this wirelessly in the future but I had the adaptors spare.
They are the old standard of 14 Mbit/s, so aren't compatible with anything available now, but fast enough for downloading some on-demand TV shows (or are they?).
As a responsible radio amateur I should have never have allowed any evil power line network equipment into my home, but I had to give them a try.

I connected a laptop in place of the Sky box and transferred a large file from a network share, through the pair of devices. They were recognised as being 10Mbit Ethernet, so there was no way the 14Mbit/s was going to be reached. In fact the file transfer speed was around 540KB/s (4.5MBit/s), which is what you would get from 802.11b WiFi (11Mbit). Both devices were on the same ring main and upstairs, in different rooms. One was located in the same room as the radio equipment and the PC that was running PowerSDR.
This is lower than the internet connection speed (9Mbit, with a top download speed of about 7.5Mbit/s). But it's fast enough to watch TV through and download on-demand shows.

I picked an empty frequency to check for the noise level, at 10.544 MHz. Using AM in a 6.6KHz bandwidth, the background noise with the devices unplugged from the mains was -97dBm on the wire antenna (no ATU).
When the HomePlug adaptors were plugged into the mains, there were a few short bursts of noise which were hard to get a meter reading from, and then there was a 'click' every second, which was hardly moving the average s-meter reading. Inside the amateur bands the clicks could not be heard over the background noise, there are notches in the amateur bands.
When the file transfer started, the noise on 10.544 increased by 14dB to -83dBm. It was just as if the noise level had increased, no peaks in the spectrum could be seen. Inside the 7 and 14MHz amateur bands there was no increase in the background noise, other noise sources were large enough to hide anything coming from the HomePlugs.

When transmitting a 5 watt carrier in the 7, 10 and 14 MHz bands, it looked like there was a slight drop in transfer speed for a few seconds (to maybe 450KB/s) but then it went back up to the same as before. Probably going into error correction before adjusting the carrier frequencies used. 

If you are thinking of buying a set of new HomePlug adaptors then you might get totally different results because of the wider bandwidth used, and they will ruin any shortwave broadcast reception but these have made so little difference to the amateur bands that I've kept using them.



Monday, 2 September 2013

JT65

JT65 log from a few minutes of calling CQ on 14.076

Worked G7RNX/P tonight while he was on Snaefell (SOTA GD/GD-001), on 70MHz FM. I was using my Wouxun handheld and Garex flexi whip antenna near the sea shore on Walney.

Had a problem with the sound on my old laptop (Samsung N150 netbook) yesterday, I was setting it up to use with the FT-817 and instead of a proper data cable, I thought I'd keep it simple by using VOX through a 3.5mm jack - RJ45 cable (with some resistors to drop the level). That worked OK, once the loudspeaker volume was set to the right level (around 20%).
For receive I used a 3.5mm cable from the 817's headphone socket to the laptop's mic socket. I got the level right but then after a few seconds the meter dropped right down on the laptop. I thought there must be a bad connection somewhere. But monitoring the input through the laptop's speaker proved the signal was getting from the radio into the computer without any breaks.
If I unplugged the cable from the laptop and plugged it back in, it would work for a few seconds again and then stop.
I noticed that a message popped up on the laptop every time I plugged in the cable, telling me I'd plugged something in. I've used PCs before which have tried to auto-detect which socket has a microphone plugged in and which one has a speaker plugged in, and failed to detect it properly.
So I tried uninstalling the Realtek application which was installed when I got the laptop, is there any need for a separate application to control the sound? Probably not, unless you really must have some fake surround sound effect.
Uninstalling disabled the sound device until I rebooted, but then Windows 7 recognised it and installed the standard driver for the Realtek audio. No more auto-detecting of plugs, and it worked without cutting out.
The only thing that had changed was the levels, the output from the speaker jack was slightly higher for the same % on the slider.

Sunday, 11 August 2013

Programming Cables

After almost giving up on the Alinco DJ-G7 programming software (hardly ever connected to the radio or it failed halfway through reading/writing), I had another go with it yesterday.
After reading these instructions I tried changing the baud rate in Windows Device Manager to 57600 and it connected first time using a USB-serial cable (in Windows 8).
I still got the odd error when reading/writing a large number of memories at once but this may be the radio at fault and not the software, see this page about some alternative programming software.
I didn't think any applications still used the Windows serial port settings, usually it is set somewhere else and the Device Manager page was not something you would ever have to change.
I find it easier to export the Alinco's memory data to a CSV file and edit it in Excel, that way the memories can be programmed in on the go, uploaded and then sorted by frequency etc.

Today I tried connecting my Icom IC-2800 to the PC. I had the CS-2800 programming software but never had any success in getting it to connect. The Icom OPC-478 cable is the same wiring as the USB cable I used to program the Alinco DJ-G7 (a single data line on the ring of a 3.5mm jack plug), so I tried that cable.
I have 2 of these cables which should be compatible with the OPC-478. The first one did not work, I thought it might be something to do with running the old Icom software in Windows 8 or the baud rate (I'd got suspicious about the Windows baud rate settings after getting the Alinco to work) but then I read this message where the writer tried several cables and only one worked. I tried my other OPC-478 type cable and once the COM port was changed to COM2 (the CS-2800 software only allows COM1 to COM4), it worked perfectly. I even tried the Windows baud rate at both 4800 and 9600 and it made no difference.
What is the difference between the 2 cables? The only thing I can think of is that Cable 2 had the ring of the jack plug at 2.78V when not connected to any radio, and the non-working Cable 1 had this at 3.3V.

Saturday, 10 August 2013

Brown Carrick Hill

A more successful SOTA activation yesterday than Wednesday's attempt at See Morris Hill. Brown Carrick Hill (SOTA GM/SS-260) is near to Ayr and Kilmarnock and there are a few people listening to 145.500 in the daytime.
The true summit is not the part with the masts on, it is to the west, across a bit of boggy ground that is below the 25m limit of the activation area.






Brown Carrick Hill masts today

The masts in 2009 when I was last here
Some of the antennas have gone from the masts, all the emergency services have now moved to TETRA (the 4-stack dipoles with extra supports). DAB antennas are on the most distant of the 3 masts.

This ship was just off Ayr





See Morris Hill

Another 0-point attempt at See Morris Hill (SOTA GM/SS-274) on Wednesday afternoon. 2 QSOs were made, the furthest being to MW0PAD in Holyhead. See Morris Hill is in a bad location for the south because Criffel is in the way and there doesn't seem to be much activity in the Carlisle area, at least for SOTA chasers.

Used the FT-817 into a half wave mobile antenna. The poles are from an old garden gazebo which we were throwing away. They are just the right size to fit in a car boot and the mobile antenna fits inside one of them for carrying. The coax is connected through a SO239 coupler.

The radio mast at the top of the hill is known as Riddings Hill.

Tuesday, 6 August 2013

ADSL

"Downgraded" from Pro to Unlimited  broadband today, still have my static IP address after restarting the router.
Getting a sync speed of nearly 10Mbit now, improved since I got rid of the "filter" that was really just a splitter (I must have had it left over from an old dial up modem). Thought it was normal (about 5-8 Mbit) until the new Sky box got plugged in and speed dropped to 3Mbit.
Now there's no limit, I can get the Sky boxes networked for iPlayer etc. I've got a couple of old HomePlug adaptors (14Mbit) to try, see how badly they wipe out HF!

Monday, 5 August 2013

O2

O2 have moved all their 900 MHz GSM cells into the 955-960 MHz band (channel 101 - 124).
This clears channels 37 - 59, probably for 3G or 4G.
Now in this area:
Thorncliffe, Barrow
18447 ch108
28447 ch112
38447 ch122

Salthouse Road, Barrow
13694 ch123
23694 ch103

Howard Street, Barrow
13469 ?
23469 ch105
33469 ch111

Dalton TV mast
13459 ch110
23459 ch102
33459 ch116

Morecambe Bay (BBC FM mast)
10439 ch104
20439 ch120
30439 ch118

Sunday, 21 July 2013

Fatal Python

Rather scary sounding error in WSPR, happens after running for a few hours. Only in Windows 8.

Sunday, 14 July 2013

CB net

It looks like there is still a bit of activity on CB in the north west, it's very quiet round here in Cumbria but I'll have a listen out for these.
http://s3.zetaboards.com/copythat/topic/7636272/1/
Channel 38 UK at 2pm today.

Saturday, 15 June 2013

S-Meter

Some meter settings from service manuals.
Yaesu FT8900:
1 dot = -5dBuv
Full = 23dBuv

Yaesu FT817:
S1 = -3dBuv
Full = 22dBuv
On FM only

Alinco DJG7
S1 = 0dBuv
Full = 20dBuv

Icom IC2800
2 dots = 0dBuv
Full probably around 15dBuv

Saturday, 1 June 2013

More antenna results

Full results so far




Mobile / Handheld Antenna Test

Tested some more mobile and handheld antennas using my RTL TV tuner dongle in the car.
There was also a Moonraker 2m/70cm mobile antenna which I'd bought recently and which is now getting used as my main mobile antenna (see earlier blog post).

1. Straight whip with PL259 connector, a 1/4 wave on 145MHz
2. Nagoya NL77B 2m/70cm PL259 mobile
3. Nagoya NA702 2m/70cm SMA flexi whip. This isn't resonant on the amateur bands at all, it seems to really be tuned to around 165MHz, making it more useful for scanners.
4. Watson Regular Gainer BNC flexi whip. Sold as a scanner antenna, it is tuned to 150/450MHz.
5. Watson WSMA-7000 2m/70cm flexi whip.
6. The stock antenna from a Uniden Bearcat UBC3500 scanner. 

The USB device shown is a cheap TV/FM/DAB tuner based on a RLT2832U and R820T chip design. It cost about £7 and can tune from 24 - 1800 MHz in all modes and bandwidths using RTLSDR software. The SDR# software has a spectrum display with a dB scale which I used for this test.
I set the receiver gain so that the strongest signal in the SDR bandwidth (it converts down to a 2 MHz bandwidth for the software to process) was around 10dB below full scale to make sure nothing was being overloaded.
All antennas were tested on a magmount on the car roof. The car roof makes it slightly off vertical polarisation but at VHF it probably won't make much difference with these short antennas.
The coax shown in the photo is the original (75 ohm?) stuff which came with a short TV antenna whip on. I just soldered a PL259 plug onto it.
 Here are the results, I took readings on 2 different bands, around 140 and 164 MHz. These give a good signal source as there are some nearby transmitters operating 24/7. On 140MHz I had the RF gain turned up full without overload. I turned it down a bit on 164MHz. The USB tuner is off frequency, usually by about 45ppm but I didn't bother correcting it for this test.
All readings are in dB relative to whatever I got with the 145MHz 1/4 wave.

Photo Antenna 140 MHz 164 MHz
0 Moonraker Mobile -1 -1
1 Straight Whip (50cm) 0 0
2 Nagoya Mobile -2.5 -1.5
3 Nagoya 702 SMA -6 0
4 Watson Reg Gainer BNC -5 -10
5 Watson 7000 SMA -10 -23
6 Uniden UBC3500 SMA -15 -9

The straight whip is the best performer, but isn't suitable for UHF. The Moonraker and Nagoya mobile antennas are similar on UHF but the shorter length of the Nagoya is probably letting it down at 140MHz.
Antenna 3, the Nagoya 702 flexi whip, is shorter than any of the mobile antennas but is equal or better than the larger antennas at 164MHz. This is in line with what we see from the SWR readings of this NA702, it also shows that the mobile antennas are not really that good up at 164MHz if they can be beat by a 29cm long whip.
At 140MHz the short length and 165MHz tuning of the NA702 is showing, with -6dB gain. The Watson Regular Gainer is even shorter at 21cm but has 1dB more gain on the lower frequency. The extra loading coil needed to get it working on 150MHz is narrowing the bandwidth a bit though, with -10dB gain on 164MHz. It's marketed as a 25-1900 MHz wideband antenna but the NA702 (which doesn't look like it could have any loading coil inside it) is actually a better choice if the 8cm extra length isn't a problem (try the Watson Regular Gainer around 200MHz - it's hard to tell if it's even plugged in!).
The Watson 7000 SMA antenna is very poor at 164MHz, probably because it has been carefully tuned to the amateur bands despite its small size, and this makes it useless for anything else. Even the Nagoya NA702 and Watson Regular Gainer (neither of which are resonant in the amateur bands) will be better than this on 145MHz. But it is one of the shortest and this is going to limit the bandwidth for anything you could transmit into.
Lastly, the Uniden scanner's stock rubber duck antenna isn't very good at anything (it's just as bad on UHF), but it's the smallest. I'd guess it was designed for about 160MHz.

For the car, I'd choose the Moonraker if I was looking for something compact.
For short under 30cm handheld antennas I'd choose the NA702 even though the tuning is a bit off.
Another time I'll test some larger mobile and handheld antennas.





Friday, 17 May 2013

More 6m WSPR

50MHz conditions are getting better
Just as I'm posting this, I'm getting someone coming through at -90dBm on 50.293 but it's not WSPR because the transmission was only for one minute and not two. Could be some other JT65 type mode. The centre frequency was around 50.294610 MHz.

Monday, 6 May 2013

6m WSPR

GM4FVM and G7SKR (Warrington) received me on 50 MHz WSPR today. Also M0XSD (Frizington) and G7IEI (Westhoughton) on 28 MHz.
HF/6m at these distances is just as interesting as getting Italy etc.
Had a play with the JT9 data mode today too, getting to Japan on 21 MHz. I still prefer WSPR though.

Friday, 3 May 2013

Noise

The background noise level on HF (especially 28MHz) has dropped today, something must have been switched off nearby.
At 28.125 MHz, the noise is now -106dBm in a 2.5KHz bandwidth (Antron 99 on the back of the house), recently it was in the -90s which was making it impossible to receive any weak signals.
At 50.295 MHz it was -116dBm on the Comet GP15 tri-bander on the chimney, same bandwidth.
I tried WSPR on 50MHz today but got no transmit or receive reports.

On 14MHz, the Antron 99 and wire antennas are within 1dB of each other on receive (both tuned for minimum SWR with the LDG Z-11Pro II tuner) for a local signal. The background noise level is lower on the Antron though.
On 14MHz the Antron's SWR is very high but the tuner still handles it without any problems. The wire isn't designed for 14MHz either, it's acting more like a 10MHz half wave/20MHz full wave.

 Antron 99, all tuned for best SWR, 7:40pm local time. 2.5KHz bandwidth.
14.095 MHz = -102dBm
18.140 MHz = -94dBm
21.095 MHz = -91dBm
24.925 MHz = -96dBm
28.125 MHz = -105dBm
29.695 MHz = -107dBm





Mobile Antennas

Nagoya NL77B 2m/70cm mobile antenna. I've had this for over 3 years. It's not resonant on 2m, with the SWR not even going below 1.5:1 on any VHF frequency.
It's about 40cm long, so shorter than 1/4 wave on 145 MHz.

Last month I bought another compact 2m/70cm mobile antenna, the Moonraker MRQ525 which is slightly longer but still less than 1/4 wave at 145 MHz.
There isn't much of a difference between them in SWR readings, neither give a very good SWR when used on the same mag mount.
I compared them on receive along with a straight 145 MHz 1/4 wave whip, on the same mag mount.
In the 145 MHz amateur band, both were worse than the straight whip (they are shorter so expect them to be worse) by between 0 and 1 bar on the Yaesu FT-8900 meter.
At around 165 MHz, there was little or no difference between all 3 antennas, the 2 dual banders would be around 1/4 wavelength tall at this frequency. A straight whip cut for the exact frequency would be better but then it would not be a match for 145 MHz.
At around 455 MHz, the dual banders were very similar, but the straight 145 MHz 1/4 wave was down by around 3 signal bars (5 bars on the dual banders was 2 bars on the straight whip).
Without the centre phasing coil, the straight antenna acts as a 3/4 wavelength on UHF, with an uneven radiation pattern. That's fine if you have no interest in UHF at all.
There was nothing in the 430 - 440 MHz band to test it with at the time. The results would probably be around the same as on 455 MHz as they all seem quite wideband.
At 393 MHz, which none of them were designed to cover, the straight whip was still about 3 bars down and the Moonraker was slightly better than the others.
I also had a Watson W770 2m/70cm dual bander but this has developed a fault which made it worse than all 3 of the tested antennas.
A Watson W770 copy (by Sharmans) that I also have, is a bit worse than the 2 short dual banders around 165 MHz but better on 145 MHz.

Although the Nagoya is a 'cheap' brand, mine has had no faults after 3 years when it has been left on the car day and night, it is solidly built. I've had Moonraker antennas fail after a short time before, so it will be interesting to see what happens to this one. They are probably all built in the same factory in China anyway.
For everyday use where wideband reception is also important, these small dual banders are as good as anything else. Higher gain models will have smaller bandwidths.

Saturday, 20 April 2013

Grassgarth Heights

Had a walk up to Grassgarth Heights this afternoon. Took a 19 element 23cms yagi and a 10m half wave vertical made on a fishing pole.
Got 2 QSOs on 1297 MHz FM with G7RNX (Dalton in Furness) and MW1FGQ.
Didn't make any contacts on 10 metres but it seemed to work OK. I could hear some distant CB activity on the UK FM band, could have been Manchester. All that would have been buried in the noise at home.
I doubt anyone would be monitoring 29.600 or 51.510 FM fron home except when propagation was very good.
Grassgarth Heights is a HuMP summit with the reference G/HLD-020 and although I didn't feel like climbing the wall to get to the top, I think I was still within 25 metres.

Tried a new route this time, going from the south of the hill on the footpath that starts at SD358820








Maycom CB on 10 Metres

Convert EM27 CB to 10Meters

Cheap 10m mobile rig if you have one of these spare.

Sunday, 7 April 2013

Sunday, 17 March 2013

8350 CPU-Z

I've only got 1GB RAM in this thing, the packet that the memory was in said 2GB!
Core speed is only showing 2.8GHz, it gets turned down to 1.4GHz when idle and only reaches the full 4GHz when doing serious work.






AMD FX-8350

New CPU and motherboard fitted this morning. AMD FX-8350 8 core 4GHz.
Still waiting for new RAM to arrive so just stuck 2GB in.






Monday, 11 March 2013

Switch Mode PSUs

Page on leakage current from the outputs of cheap switch mode PSUs
I started looking into this after getting a small "shock" from the metal case of the iPhone 4S, using 2 different chargers. This was with both a very cheap (about £1 including delivery) and what I believe is an official Belkin USB charger.
I measured around 100V AC between the 0V DC line of the USB cable and mains earth for both. Other chargers had some AC voltage but much lower. Because the cheap charger was so badly made, with solder almost bridging the isolation gap between high and low voltage sides, I thought that the leakage was down to poor insulation. But after the Belkin did the same thing, I looked online a bit more and found that it is probably down to the 2.2nF capacitor that is often connected between the high voltage rectified mains and the 0V DC output line, for interference suppression.
When I measured the leakage current to earth from the output, through a 100K resistor (in case there was actually a solder bridge!), I was getting about 150 microamps AC current from both chargers. This type of equipment is allowed up to 250 microamps of AC leakage to the output, so perfectly legal chargers can still give a bit of an electrical buzz if the USB powered device has exposed metal. The problem is when your phone case touches some other wiring like the input to audio equipment, and it gets the hundreds of volts from a charged capacitor.
Leakage currents might start getting dangerous if you have a lot of unearthed equipment connected together (multiple TVs and set top boxes daisy chained or plugged into the same unearthed amp). I measured over 300 microamps from the USB socket of a TV that was also plugged into the RF output of a SKY+ HD box. Unplugging the coax brought it down to 150.

Tuesday, 5 March 2013

2.1 GHz Tropo

This is the log from the Netmonitor app on my phone, showing which phone cells it has been receiving today.
The ones in Newtownards and Southport are on 2.1GHz 3G (3 network) and were received in the Seascale area this afternoon.
Cell 20764 is probably in the Southport area too, as it has the same LAC of 22 (Lancashire area).
2G phone networks from the Isle Of Man are often stronger than the UK ones along this coastline, but receiving Northern Ireland on 2.1GHz is a new one for me.

Friday, 1 March 2013

Strange CB/10m handheld

AnyTone ST-118 portable CB radio http://www.aliexpress.com/item/AnyTone-ST-118-portable-CB-radio/723098383.html
A 16 channel PC programmable 25-31 MHz handheld with CTCSS. These look like they are meant for business use but who would use that band with handhelds instead of PMR446/PBR frequencies? I can't find any mention of them online except from Chinese sellers.

Thursday, 28 February 2013

Newton Fell North

Newton Fell North - WOTA LDO-097
24th February 2013
70 MHz, 145 MHz and 433 MHz FM

Microwave and WiFi antennas, could be for caravan site down the hill

Lower dish towards Kendal

Pointing North East

Howgills from Newton Fell North

Coniston Fells from Newton Fell North
New GSM-R mast at Thwaite Flat near Barrow

Saturday, 9 February 2013

APRS news

I think the IC-2800 is transmitting better packet audio than the last radio. I was received by G7DNM at Darwen yesterday.
While on the way to Ulverston today I was received by G0OFY-1 also in the Darwen area. I was by Pennington Lane Ends at the time.
Received G1JTD who was on Loughrigg (while I was at home).

Friday, 8 February 2013

PC Upgrade

In the next week I'm going to replace the motherboard, processor and RAM in my home PC.
I've got 3 different CPUs to choose from, which one I get will be decided later.
AMD FX-8350 8 core
Intel i5-3470 4 core
AMD FX-6300 6 core
All with 8GB of RAM.
The 8350 and 3470 are around the same price, with the 6300 being quite a lot cheaper. The benchmark puts the 8350 highest but the i5 does better on some tasks.

My current PC build:
AMD Phenom X4 9550 quad core 2.2 GHz (since October 2008)
4GB DDR2 800 RAM (since October 2008)
Asus M2A74-AM motherboard
ATI Radeon HD-5400 graphics
300GB SATA HDD (I had a 1TB but put that in the NAS and used this, bought in 2006)
250GB SATA HDD (since October 2008)
2 x SATA DVD writers (one old and one new)
FireWire PCI card
USB 3.0 PCI card
Be Quiet PSU