Wednesday 22 December 2010

Puxing PX-2R

I recently ordered a Puxing PX-2R handheld and it arrived today.
This covers 400 - 470 MHz, with 2 watts RF power.
The battery is a 3.7v mobile phone type and charging is through a Nokia type 2mm power connector at 5 volts, so it will charge from a USB port (cable supplied) or Nokia phone charger.
It has a female SMA antenna connector (unlike other Chinese handhelds).
The manual has no information about how to store frequencies into the 128 memories or connect to a PC for programming, but there is programming software available on the Puxing website and the 2.5mm speaker/mic socket must be used for the PC connection. There is no mention of 6.25KHz steps either, the menu allows only 12.5 or 25 KHz channel steps, but if you type in a 6.25 KHz offset frequency (e.g. 446006) then it tunes in 12.5 KHz steps from that frequency (446.00625, 446.01875 etc.)
As usual for this type of radio, the S-meter is useless, taking about 2 seconds to respond to any change in signal and showing either full or nothing.
For £28 including postage this is worth the money though.
Forum discussion on this handheld
Instructions on storing memories

Thursday 9 December 2010

Nokia NetMonitor

I've got an old Nokia 3310 phone which I've had for nearly 8 years. I don't use it as my main mobile any more (not since December 2004), but after I got a new phone I unlocked it and enabled the Network Monitor functions. The unlocking was through a serial port cable which goes to a special connector underneath the battery.

The Network Monitor screens show lots of data about the phone's battery, software and radio transceiver. The best ones are tests 3,4,5,11 and 17. The current channel number and Cell ID are shown, as well as the channel and signal strength of nearby cells. Signal strengths are in dBm, how can a cheap mobile phone display signal strengths in 1dB steps but on the amateur bands we still have to have meters in S-units which may or may not be about 6dB per unit except when we're using FM?

Other phones often have some kind of Network Monitor screen (there's an Android app which can show the Cell ID but not the channel number, at least on my HTC Hero). On my Sony Ericcson K750 I could get Cell ID and channel numbers on a built in test screen.

The most interesting test of all is number 17, BTS Test. This locks the phone to a single radio channel, so it can't look for the nearest base station. The channel number is selected by storing it as a phone number at address book position 33 on the SIM card.
You can go up a hill and get a base station far away (over 50km), as long as there is nothing local on that channel. At home in an upstairs room I can get the Vodafone base station at Lancaster (the same site as the GB3LD repeater), which is on channel 77 (950.4 MHz).

The base stations are identified by the country code, network number, LAC and CID. LAC is the region of the country where the station is. This helps give a rough idea of where an unknown base station might be if there are none nearby.
For Vodafone, the LAC in this local area is 170.
The CID is the Cell ID. It could be used more than once in the UK, but with a different LAC. Different networks have different CID numbering systems. O2 has the most meaningful.
For O2, the CID is usually a 5 digit number.
The first digit is the sector (the direction of the base station antenna, where there are usually 3 different antennas on separate frequencies, spaced at 120 degrees round the mast). The sector number is 1, 2 or 3.
If the CID is less than 5 digits for an O2 site, an omnidirectional antenna is being used or only a single panel. This might be because it's an old site which has been around from the analogue days or it only has to cover a small area like inside a tunnel.
Sector numbers usually go clockwise starting with 1 as the most northerly pointing antenna. So a CID of 15432 would be base station 5432, beaming north. 30439 would be base station 439, probably beaming towards the south-west. If this was simply CID 439, it would probably be an old site with a single omnidirectional antenna.
If the last 4 digits are 0001 to 01499 then there's a good chance the site had been used for the analogue cellular system, but not always, some newer sites use numbers in that range.

Some older Vodafone cells use a similar numbering system but with the sector number at the end. If the last digit is zero then it is omnidirectional. Newer sites don't follow this system and the numbers mean nothing.
The Lancaster Langthwaite site I get at home has a CID of 1643. This is an old site, which was in use for analogue phones. On the Sitefinder website, this is shows as being site number 164. I'm roughly west of Lancaster, so sector number 3 will be mostly directed towards Barrow.
At the railway station in Barrow there is a Vodafone site with 2 omnidirectional antennas. This is site 3753 on Sitefinder and the CID is 37530.

Channel numbers on the 900 MHz band (O2, Vodafone) are 0.2 MHz offsets from 935 MHz. So channel 75 is 950 MHz.
O2 normally use 37 - 59 and 101 - 124.
Vodafone normally use 65 - 99
On the UK networks, only the odd channel numbers are widely used, except for channels 123 and 124 (for some reason channel 123 is missed out and 124 used instead).

At 1800 MHz, T-Mobile are using the channel 575 - 715 range and Orange in the 750 - 870 range, but that might change now it's the same company.

Some local sites:
Morecambe Bay
CID 10439, channel 109 (North)
CID 20439, channel 101 (towards Ulverston)
CID 30439, channel 57 (towards Barrow)

Lancaster TV mast
CID 10210, channel 53
CID 20210, channel 55
CID 30210, channel 124

Morecambe Bay
CID 2930, channel 91

CID 1643, channel 77
2 other sectors unknown channel numbers

Dalton TV mast
CID 8334, channel 65 (Dalton town centre)
CID 8335, channel 93 (south-west)
CID 8336, channel 97 (north)

All except Dalton TV mast used to be analogue sites.
Old analogue control data channels:
Morecambe Bay Vodafone = 935.8375 (omni)
Morecambe Bay Cellnet = 943.5125 (omni)
Langthwaite Vodafone = 935.6875 (sector 1), 935.8625 (sector 2), 936.0375 (sector 3)
Lancaster TV mast Vodafone = 935.7375 (omni)
Lancaster TV mast Cellnet = 943.0875 (omni)

Sunday 5 September 2010

Nagoya UT-108

Don't buy a Nagoya UT-108 dual band mini magmount antenna. They're available on Ebay from a few places. There are a few other in their range of mini magmount antennas, which are smaller or have different connectors.
On my car roof, it was a lot worse on 70cms than the proper mobile antenna (Watson W-770 copy) which was mounted quite close to the ground on the tailgate. Probably the RG-174 coax being so lossy but it didn't seem to be resonant on any amateur band at all. Even when the car body was in the way, the W-770 was much better.
The mini magmount was OK around 165 MHz, compared to other antennas, but none of the others were meant to work on that frequency anyway.
Other mini magmount antennas are probably the same, but the last one I had (I think it was from Moonraker) fell apart soon after I bought it. Other stuff from Nagoya looks like it's a direct copy of the Diamond/Watson antennas.

Wednesday 28 July 2010

Multi Ranger 200

Watson Multi Ranger 200 on the car. I've not tried this at over 30mph but probably won't be driving very far with a HF mobile antenna on.

Wednesday 21 July 2010


RG8-Mini (or RG-8X) is the 50 ohm coax size which is somewhere between RG58 and RG213, 7mm diameter. You might use it where you need flexible coax but where RG58 isn't good enough. But is it really any better than RG58?
It seems to be sold more as a high power HF cable than for use where low loss matters, and I first saw it being used on CB. There were red and grey versions of this cable.
A few years ago I made up a cable of black RG8-Mini, about 11 metres long with PL259 plugs on and sometimes used it for portable operation. I thought it would probably be better than RG58 so wasn't too worried about the loss. But this week when I was on Muncaster Fell I had a listen around 433 MHz and didn't hear very much. I could hear more on my handheld's own antenna than on the 2m/70cm mobile whip that I had set up on a pole.
When I got home I measured the loss of this 11m of RG8-Mini on 2m and 70cm. With a very short piece of RG58 I was measuring 9 watts on 70cm. Replacing that with my coax cable reduced that to 2 watts! That's about 6.5dB loss or 0.6dB per metre. RG58 is supposed to be better than that on 70cm. At 144 MHz, the loss was about 2dB which is more like RG58 should be.
The official figures for RG-8X are better than this but it doesn't seem as much of a standard as RG58 or RG213. I think I bought mine at a rally and I had some on a 2m/70cm dual bander at home before I put decent coax on it so that might have been the same piece of cable.

Wednesday 7 July 2010


There's some activity on 70 MHz WSPR now, on 70.0286 MHz. I can receive G0MJI from Liverpool, using my Icom IC-7000 and the dual band 2m/70cm colinear on my chimney. On the proper 70 MHz dipole in the loft, there is no improvement in S/N because there is more noise indoors. I've nothing to transmit on 70 MHz SSB though.
Alex G7RNX in Dalton was also on 70 MHz WSPR on Sunday and could be received by G0MJI and G3ZOD (Stockport).

Made a PC to radio interface for an FT-847 before finding out it wouldn't work properly because...
On the Yaesu FT-847 there are separate connectors on the back for FM and SSB data modes. The 6-pin mini DIN socket can only be used to transmit on FM (there seems to be receive audio on SSB through it though). On SSB, transmit and receive audio are through a 3-pole minijack socket. The tip of this jack is for transmit audio and PTT (ground through a resistor to transmit).
The 6-pin socket can be used for the PTT on both FM and SSB.
Connecting a cable directly between the headphone socket on a PC and the FT-847's SSB data socket made the radio stay on transmit. There needs to be a capacitor to block any DC current path which might key it up.
It seems a bit of a strange thing to have 2 data sockets but when the FT-847 was designed, people weren't using a PC sound card for data modes so would have had a standalone packet TNC.

Sunday 18 April 2010

HF Vertical

I'd bought some ferrite rings at the rally last Sunday so decided to have a go at making a transformer for use with a HF vertical antenna.
Wound 9 turns on the ring with a tap at 3 turns for the coax. The wire goes to the other end of the coil. Connected about 7 metres of wire, taped to a 7 metre fishing pole. This had a low SWR at about 28 MHz, and also around 7 MHz (why 7 MHz?).
Went to Kirkby Moor (SOTA G/LD-049) this afternoon and tried it out. On 28 MHz I talked to G6MZX (Thornton In Craven), G6LKB (Ulverston) and G4TUZ (Lancaster). G4BLH and G1KLZ couldn't hear me so it might not have been working very well, I'd expected them to be stronger on that band.

Worked G6LKB and G6CRV (Heysham) on 18 MHz, both were strong signals.
Transmitted some WSPR using the recording stored on my phone, on 7 and 18 and 50 MHz. There was only one report on 7 MHz but on 18 MHz there were a few from the USA. On 50 MHz, I got -28 and -24dB reports from G3ZOD in Stockport, which was about the same as I get from home. As Kirkby Moor is a much better site, the antenna was probably not working that well on 50 MHz either.
Made another 2 QSOs on 145 MHz with other summits (Gummers Howe and Lambrigg Fell) before packing up.

On the way home I parked above Marton and did a test to compare my new vertical with the Watson Multi Ranger 200 on the car. Sent some WSPR on 18 MHz (using the fishing pole) and the reports weren't much different to what other UK stations were getting into the USA.
On 7 MHz I transmitted once from the Watson and then from the fishing pole, 4 minutes later. 2 stations received me both times and there was only 1dB or less difference between the two. A 1.2 metre long mobile antenna isn't going to be very efficient compared to a full size dipole but it was good to know that the home made vertical (which shouldn't work on 7 MHz anyway) worked about as well.
To check the 28 MHz performance against the Watson, I listened to someone in the Liverpool area on 27.800 MHz (CB channel UK21). With the Watson they were S4 but with the fishing pole they were 0.64 wavelengths at 28 MHz).

Another time I'll have to compare my transformer with the red 'long wire balun' and the same length of wire.

Friday 2 April 2010

Ofcom Frequency Search

Want to know the frequencies and locations of business radio users in your area? Once upon a time you had to buy a scanner frequency book but the nice people at Ofcom now let you search online.
Ofcom Spectrum Information System

Make sure that "Business Radio" and "Technically Assigned" are selected if you want to filter out all the on-site paging and UK General users (otherwise you'll get a list of everyone in the UK who has a UK General licence)

Results for the whole of Cumbria

Wednesday 31 March 2010

Antennas at home

I took some photos of the antennas at home last weekend while the weather was nice.

Where the HF wire comes down to the back yard. The wire is tied on to the clothes line hook with some rope and then hangs down to the ground. There is about 10 metres of wire in all, making a half wave on 14 MHz.

The Solarcon A-99 with the transformer for the wire below it. The pole is 8ft 2" diameter steel.

View from the top of my street, looking south. In the background is the south end of Walney Island and Piel Island (on the left). The mast is at the United Utilities depot in Barrow, with antennas for their 139 MHz system on it, as well as some mobile phone networks.

Tried wPrime on a Samsung N130 netbook (on its battery) and the 32M test took 137.4 seconds in Windows XP. That was about the same as I got when trying another laptop which had a 1.4 GHz Pentium M processor (which have been around since 2003).

Thursday 18 March 2010

Portable auto ATU

I've just ordered an LDG Z-11ProII auto tuner. I was wondering whether to get the Z-817 instead but you can fit an internal battery to the Z-11 so the Z-11 is better because it can handle more power.
My other tuners are an LDG AT-7000 which only works with my Icom IC-7000 and a Zetagi M27 CB matcher (it works above 20 MHz).
Below is a view inside the M27:

I've also got a Zetagi B150 CB amplifier, had it for many years but not used it for a while. It never worked well on SSB, the original circuit is actually running in Class C (there's a DC short between base and emitter of the MRF455 power transistor, through a ferrite bead inductor, in parallel with a 10 ohm resistor). Mine now has some bias current because the ferrite bead has been removed and the bottom of the switching relay coil has been connected to the base of the MRF455. This gives some bias current only when transmitting.
Circuit diagram for the B150
Why build an amp with an AM/SSB switch (changes the delay on tx/rx changeover) if it won't work on SSB? The B300 uses a totally different circuit, still using MRF455s but in a pair.

Tuesday 19 January 2010

DJ-G7 software, finally working

This morning I got a 'proper' Alinco programming cable (the correct wiring, not an Alinco part) and tried it with the programming software. The cable is USB to 3.5mm 3-pole jack plug and is a standard USB to serial adaptor. The ring of the jack plug has 2.8 volts DC on it (this is the data connection). Connected that to the Alinco speaker/mic converter cable through a 3.5mm/2.5mm jack adaptor.
I still got an error message in the programming software when trying to connect to the radio.
Using Filemon I checked whether the software was missing any DLL files (the old Puxing 777 5-in-1 software needed MSFLXGRD.OCX to work and this isn't part of a standard Windows install - it was included with the Yaesu VX7 programming software so if that was installed then the Puxing software would work). The Alinco software was trying to open MSCOMEN.DLL but the file was missing from the Windows\System32 directory. Downloaded the missing file but this made no difference, there was still the same error.
Next I tried copying the firmware to the radio, to make sure the cable was working. Downloaded the DJ-G7E firmware updater but this said the region was wrong. So I don't have the normal DJ-G7E. Tried the firmware for the universal model DJ-G7EG and that worked OK (a search for the DJ-G7EG returned mostly German results so I guess the G is for German).
Installed the correct version of the programming software for the universal model DJ-G7EG and it connected to the radio (very slowly). It takes about 10 minutes to read the data from the radio (and that's supposed to be at 57.6Kb/s!).
I bought my DJ-G7E(G) from Nevada.
With this software you can export/import CSV files which makes editing memories a lot easier (sorting them by frequency, finding duplicates etc.). This is better than the Icom IC-E91 software which had no way of sorting them. Also the bank sizes can be changed from the default of 100 memories, which is good because I don't like memories in fixed banks, it wastes memories. My UBC3500 scanner is better, it has no channel numbers, only groups which can be any size (up to a limit of 2500 channels in total).

Sunday 10 January 2010

Beacon and Cross Band Repeater

A couple of circuits I built back in 1998
This keys the rig for a few seconds every minute. Useful for testing without transmitting too much.

Cross-band Repeater:
This is for connecting 2 handhelds where the PTT and microphone are on the same wire.
Both rigs must have some output which goes high when the squelch opens. I connected the squelch control to the positive battery terminal through a diode so the battery could be removed and a wire clipped on.

Tuesday 5 January 2010

DJ-G7 programming

I got a Yaesu VX-7 programming cable (USB to 4 pole 3.5mm jack) because they are meant to work with the Alinco DJ-G7 handheld. Installed the driver (a generic USB to serial driver) but the Alinco software won't communicate with the radio, it just shows a message box with "ERROR", which I'm guessing is a comms error. I didn't want to get a real Alinco cable because you still need to have a 4 pole jack plug adaptor to use it with the DJ-G7.
When plugged into the PC, there is 3.7V on the 1st ring of the 4-pole jack plug. Is that right? The Alinco cables only seem to have 2 wires.
Made at least 4 QSOs in the 2m activity contest tonight. Tomorrow's special band on WSPR is 12 metres and I like that band so I'll be on there some time tomorrow.
Used a repeater tonight which is a rare thing for me, was on 70cm repeater GB3CR because I couldn't get Alex G7RNX on 4 metres when he was on Runcorn Hill.