Tuesday, 19 July 2016

Bigland Barrow

A visit to Bigland Barrow, one of Wainwright's Outlying Fells (WOTA LDO-112).
I'd set off this morning to do Gummer's How (SOTA G/LD-050) but the traffic slowed to a halt at Haverthwaite so I diverted to Bigland Hall and walked to Bigland Barrow instead.
This is one of my nearest Outlying Fells (or any Wainwright) and is only a short walk.
Took the FT-817 and W50 antenna, which was a change for this summit as it's usually somewhere I just want a quick walk to and only need the one contact to qualify for WOTA.
Today I made 8 QSOs, including G0HIO/P on Harter Fell SOTA G/LD-028.

View of almost the entire walk from where I parked

 A few local summits to the west

"Wartime relic, now in a state of disrepair", which is useful for increasing the antenna height


I should have been here

Another Outlying Fell, Newton Fell North is around 3km to the east. This is used as a Wi-Fi link site and one of the channels was strong enough to be picked up on my phone (SSID NF-SH, channel 116, 5580MHz) as Bigland Barrow is almost directly in line with the beam.

Sunday, 10 July 2016

Billinge Hill

Friday's activation of Billinge Hill SOTA G/SP-017
Used the Alinco handheld and 40cm whip. Not as bad for overload from all the masts as I thought it would be, even on 145MHz any interference was gone at the lowest attenuator setting (about 3dB?) so it wasn't really a problem.
Most of the transmitters on Billinge are between 163 and 183 MHz, so some way from the 2m amateur band, and on the mast furthest from the summit. Apart from Airwave TETRA around 393MHz, I don't think there are any UHF transmitters up there any more.
I made 8 QSOs from Billinge Hill, 7 on 145MHz and one on 433MHz. The furthest was G4ING who was in Hyde, around 42km away, also only on a handheld.

Summit of Billinge Hill


View towards Winter Hill


Remains of something

4 masts on Billinge Hill

Cropped from my phone camera so not the best quality, this is the one with the broadcast antennas on, and looks like it would have had emergency services pre-Airwave. About halfway up are the DAB yagis pointing towards Liverpool. Wish FM 102.4 looks like 2 crossed yagis, one towards Wigan and the other towards St Helens. The other mast is probably from the analogue mobile phone days.

Very busy mast with most of the high VHF stuff on. Furthest from the summit.

Apart from the microwave dishes, only a couple of low VHF dipoles. These might not even be used any more.

On the way here, I stopped at the slightly lower Ashurst Beacon, further north on the other side of the M58. This would be a much better place to play radio from if not after the SOTA activation, with a large car park and land open to the public. There are two viewpoints with car parks, about 2km apart on the ridge, one is better for the north, the other for the south.
Here is the trigpoint at the south viewpoint (168 metres)

Wednesday, 1 June 2016

Brant Fell and New Car

On Saturday I was at Windermere in the morning so I had a quick walk up Brant Fell (WOTA LDO-113) on the way home. Just took the Alinco handheld up there and made 2 contacts, M0AYB/P who was on the way up St Sunday Crag from Patterdale, and M0LKB at Ulverston.
Parked at SD413961 on the road to the east of the fell, where there is a parking space at the start of the footpath.










On Thursday I picked up the new(ish) car, a Nissan Note N-Tec 1.4 petrol. It has built in satnav, Bluetooth and USB music playback.
No less than 3 12v sockets - one below the dash, one behind the front seats and one in the boot. Also some good places to keep a radio out of the way.



Fixing the FT-8900 head unit to a phone holder. Screwed back together after putting cable ties through.
 




Sunday, 1 May 2016

Car Electrics

In the last few weeks I'd been having some trouble with the Yaesu FT-8900 radio which I have in the car. When switching it on, it displays the DC voltage and I'd noticed that it was very low. Under 11v with engine off. I've got the FT-8900 wired up the way that every instruction manual ever written tells you not to - through a cigar lighter plug. This is not usually a problem, I've never had a radio connected any other way in the car and never used over 20 watts mobile from the FT-8900. Also, the radio is transmitting APRS while I'm driving, with around a 1% duty cycle and 20 watts.
At first I thought the car battery was not charging and would soon be completely dead, but I did a check with the engine running and the voltage did go up, so the alternator was OK. The voltage while charging did seem a bit low, maybe 12.8v. This was while I had the radio on receive, but when switching it off, the voltage went up to the normal 14-ish. That's a big voltage drop for something drawing under 1 amp on receive. I checked the voltage drop between the negative wire on the radio and the car body, and it was very low.

It turned out the connection between the lighter plug and the socket was bad, because there was something that looked like a burn mark on the centre contact of the socket. Something had probably knocked the plug out slightly and the resistance had increased.
I cleaned the contacts up and the total voltage drop with 20 watts transmit power is around 0.3v (including the wiring from the battery).
 With the engine running, there must have just been enough voltage at the FT-8900 to let it transmit (or at least look like it was - nobody picks me up on APRS round here anyway!). I'm guessing below about 9v the radio will shut down.

One other thing I learned from all this is that the Nissan Juke (and probably lots of other cars) doesn't keep the battery charging all the time when the engine is running. This is something I'd never thought of before, normally you would leave the engine running if you wanted to power something that might drain the battery - like a high power transmitter.
After starting the car, the alternator is connected to the battery, but once the battery voltage reaches a certain value, it cuts off when the car thinks it is fully charged. Now this is a problem because I don't think the "fully charged" voltage is really fully charged, and it just replaces what energy was used the last time the car was started, and then cuts off. Searching online, I found that this is a known issue with certain Nissan Jukes and the batteries never charge properly. It also effects add-on lights which detect the battery voltage to switch on when the engine is running. Putting a load on the battery (the headlights usually work) can switch the alternator back onto the battery as the car sees a voltage drop and thinks the battery needs charging.

Monitoring battery voltage (engine stopped) with a CellLog 8S

Wiring to radio and APRS tracker. The FT-8900 cable is soldered directly inside the 3-way splitter. The APRS tracker is on the lighter plug, so I can disconnect it when not wanting to transmit data.

Sunday, 10 April 2016

WotIHeard

I've started a SoundCloud page where I upload recordings of radio activity, usually 145.500 at weekends and bank holidays.
These have the gaps taken out, and I try and get at least 11am - 3pm (peak time for SOTA activations etc.) when I'm not at the radio.

I'm using a Yaesu FT-7900 and Comet GP-15 triband antenna. At 145MHz the coax has about 1.5dB more loss than it really should do, because of some RG-58 extending it out of the loft. But on VHF, the receiver is limited by external noise, there is always some reading on the signal meter with an antenna plugged in (only the 7900 has a meter sensitive enough to show anything on external noise). No, even on 145MHz you can't get away from noise generated by electronic devices in a built up area.
Audio comes from the 'data' socket on the 7900, directly to the unbalanced input of a Edirol UA-25 USB audio capture. The UA-25 has a peak limiter enabled on the input, this only operates on bursts of noise or very high deviation signals.
Recording is threshold activated on the PC, at -29dB and 1 second release delay. The FT-7900's squelch only cuts the 'data' output by about 30dB when closed, so this is as low as the threshold can be without unwanted recordings.
After recording, I copy the left channel to both left and right, apply another limiter (in software) with a -6dB threshold to cut down the 'clicks' when the squelch opens/closes and level out differences between people using a mix of 2.5 and 5KHz deviation (I don't think the FT-7900 has narrow and wide filters based on the transmit deviation setting, like the more expensive Yaesu mobiles).
I should also do a low-cut filter too, it doesn't sound like the low frequencies are rolled off much in the radio, and as well as the DC clicks when the squelch opens/closes, I can hear who has their CTCSS left on when not on repeater channels.
I also use the Edirol UA-25 when I'm running the APRS gateway, with the PC's internal audio used for HF data modes. The red plug in the photo also comes from the 'data' 6-pin DIN socket, but that is from the 9600 baud packet output, giving unfiltered, unsquelched receive audio. This is good enough to use with digital voice decoding software like DSD+ to receive DMR transmissions. I don't think it works quite as well as a proper DMR radio but it's handy because if I find a DMR signal when using the FT-7900, I can quickly start up DSD+ and check it out, rather than having to change radio.

Thursday, 11 February 2016

WSPR in Linux

I'm typing this from Linux Mint 17.3, while running WSPR. It was quite easy to install the Windows version of WSPR 4 using Wine. The only problems were no choice of sound devices (I have both internal and USB audio, often a different radio application is using each one) and the list of serial ports for CAT control of the radio still showed COM1 etc. which don't exist in Linux. I think these can be set up to use the proper device but I just chose VOX to transmit.
When I was installing Linux Mint I chose to install it alongside Windows, and it installed itself on an external USB HDD (with the boot menu on the internal HDD).
You can see on the screenshot where I had to turn the input level up from its default of 0. It still managed to decode 2 stations with only half the time slot though.


Friday, 5 February 2016

DMR

Everyone else seems to be getting DMR equipment so I thought I'd get one myself - a Retevis RT-3 UHF handheld. It's a clone of the Tytera MD-380 and one of the cheapest, at under £120.
I've used it on my local repeater GB7MB (Heysham, Colour Code 1, 439.700 MHz) and also simplex where there is quite a bit of activity on 438.5875 MHz round the Barrow-In-Furness area.
I've not been much of a repeater user but I like the way you can see the activity on any repeater using the DMR live monitor
GB7MB log 
I can also receive a few other DMR repeaters at home:
GB7PN 439.425 Prestatyn (2nd best)
GB7CA 430.925 Douglas, Isle Of Man
GB7TP  439.6875 Keighley