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).

Vietnam

I was received by XV9AA in Vietnam on 20m WSPR today. Never received them, probably because there was loads of noise today on 20m.
I was having a look at the manual for my first ever 2 metre handheld, the Rexon RL102. That cost me £100 in 1996 and that was very cheap for a 2m handheld. It only had 20 memory channels and no CTCSS. Cheap handhelds like the Puxings and Wouxuns are better than that.

My main PC - AMD Phenom 9550. Yes, that's a floppy disk drive in there!


Old PC - AMD Athlon 3200+ (I'm using it to type this blog post)

Sunday, 28 March 2010

10m Mobile

I tried shortening the 10m mobile antenna as far as it would go (last time I tried it was resonant about 32MHz). The resonant frequency went down to around 28.8MHz which is around the middle of the 10m band.

The bottom section on its own is resonant at 53.5 MHz and the top at 57.5MHz (both have 3/8 thread fittings on them)

Yesterday I was up Stoney Cove Pike (SOTA LD-018) and could hear 2 repeaters on 6m. The best was on 50.800 (GB3ZY near Bristol - up to about S1) and the other one on 50.770 was very weak and probably GB3FH in Somerset, unless it was GB3DB at Danbury.
50.800 MHz is also Huddersfield but the stations using the repeater were all in the South West.

wPrime

I'm using my old PC (I built it in April 2006 and used as main PC until October 2008) for now until I get some new parts for the other one. I ran wPrime 2.0 on this one (AMD Athlon 64 3200+ @ 2GHz) and got an average time of 77.314 seconds for the 32M test. That was in Vista Home Basic.
This PC has a real serial port on baord, something it's hard to find on a motherboard these days.
The case is not the original - when I built a new PC in October 2008, I kept the old case for the new motherboard because it was a good case (Lian-Li PC-7). This black case was very cheap. There's a 550w Colors-IT PSU in there, from the old system.

My laptop, a Philips Freevents 11NB5800 got an average of 71.2 seconds in wPrime for a 32M test, so slightly faster than the desktop. That has a 1.2 GHz Intel Core Duo processor so slightly faster than a single core 2 GHz.

Friday, 26 March 2010

Pc power supplies

The faulty PSU in my PC is a 700w Arctic Power and I've ordered a 530w
Be Quiet Pure Power to replace it. That power rating should be OK, i'm
only using the onboard graphics.

Pc power supply

i think i need one new pc power supply - last night while i was in the
middle of encoding a video, something started smelling of burnt
electronics. everything was still working but after switching
everything off in the room, i had a sniff round and it was definitely
coming from the back of the pc. I've swapped over to my old pc for
now, but that has something wrong with the motherboard - i put a new
cmos battery in a few weeks ago and its already dead. Still works
though, just needs the clock setting when started. It's a 2 ghz Athlon
64 3200 with 1gb ram. my main pc is a quad core amd 9550 with 4gb ram.

Tuesday, 23 March 2010

QSL Letter

I got a letter in the post from a German SWL today (Frank from Scheibenberg) to report reception of my WSPR signal on 7 MHz. The report was for the 18th of March and he was using a 1 metre diameter active loop antenna (Wellbrook ALA1530) indoors.
I was surprised to get a reception report by letter because reports are usually uploaded straight to the internet by WSPR but he must not have been online because there is no record on wsprnet.org that anybody in that location received me (I was being received by other German stations at the same time).

Here are the stations less than 500km away who received my 14 MHz WSPR signals.
How are these short distances being covered? Are they short skip of the type you would get on 3.5 - 7 MHz or a more direct path?
G3SZU IO84oc 27
G4YTM IO93gl 134
G4APO IO93ik 146
G4PEC IO95ga 152
G0IMX IO92ao 186
G0NNF IO92al 199
G8MKE IO92al 199
G4EFS IO82vj 201
MM5AHO IO85dw 206
GM0NBM IO85ax 214
G4NJW JO03dh 247
G3RMD IO81xv 258
G0KTN IO81ti 311
G0TTV JO02rn 354
G4CAO IO91si 357

Saturday, 20 March 2010

1.8 MHz

I've managed to get somewhere on 1.8 MHz from home, by plugging in just the centre of the coax that goes to my HF wire. The Z-11Pro tuner will tune that and I was received on WSPR by G6WRW in IO82UJ (Kidderminster, 200km). I was -26dB S/N, with 10 watts, so I only just made it.
There's S9 of noise here on 1.8 MHz and I'm receiving nothing. I thought the computer might have shut down or something with that much RF only a few centimetres from it but it wasn't affected.

Found a site with circuit diagrams for the Ham International/Hygain/Tristar SSB CB rigs.
Stalker IX CB with circuit diagram (this is the AM/SSB only model, not the one with FM but it's mostly the same). Lots of other information on CB rigs on that site.

HF mobile

I got my new ATU today and have been testing it at home. This one is fully automatic so just needs to have some RF for it to start tuning. There is a control socket (3.5mm jack) too which can be connected to the Icom so it can be operated by pressing the tune button on the radio. But I'll be using this tuner mainly with the FT-817 so it'll be fully automatic.
There are some SWR LEDs on the front of the tuner, on some bands it would not try and tune for a 1:1 SWR, giving about 2:1 at the first attempt. It will probably learn after a while to get a lower SWR, with a few changes at the start of each transmission. Like the AT-7000 tuner, it won't let me use my wire on 1.8 MHz but I'm not surprised with it being 8 times too short on that band. I'll have to try and get some signal out on 1.8 MHz, maybe just using the centre of the coax. For receiving on that band I've been using the A99 because even though it's so inefficent at 1.8 MHz (it'll be like a short circuit with hardly any coupling to the radiating element either), background noise is still what limits the receiver.

Tried some HF mobile whips on the car, I've had these for a few years but not used them much because I only have a smallish magmount on the car. The roof of the car isn't flat enough to hold the larger magmounts. So there's no way I'm going to drive around with a large HF whip on the car.
I found 4 HF mobile whips. I wasn't sure which top sections went with 2 of the bases but 2 were marked up.
28 MHz? - this one was resonant at 32MHz and didn't have many turns on the coil. Probably 28 MHz with the top section too short.
24 MHz? - this was resonant about 26.5MHz so I'm guessing it's meant to be 12 metres.
18 MHz - here is a graph for the 18 MHz whip -


14 MHz - this one looks OK, even with the small magmount -


I don't know why the 12 and 10 metre antennas were so far off frequency, I must have tuned them some time, probably on my old car but the 14 and 18 MHz ones were also tuned on that car so why was it just those? Unless I've mixed up the top sections but if they were swapped round, they couldn't both be too short?

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, 16 March 2010

29.600fm

There are a few people using 29.600 FM in the Lancaster and Morecambe
area, usually around 10pm each night.

Sunday, 14 March 2010

Google Maps

Here I am on Google Maps Street View
Most streets and roads are now on there, it's really good for checking out what antennas someone else has up!
I walked up Black Combe (SOTA G/LD-030) this afternoon. Just took the Alinco handheld with its own antenna. Made QSOs on 23cm, 70cm and 2 metres. Most were on 70cms which was unusual, and 2 were on 23cm (MW1FGQ and G7IEI). It was a bit cold and windy on the summit but not bad on the way up/down.
I was also trying some APRS on 28MHz FM, just to see how it worked on that band. I was receiving at home on some frequency towards 29 MHz and using the FT8900 in the car with 20 watts into a Sirio ML-145 CB antenna. The best DX was from the car park at Whicham (spot the radio mast in the background) back to home, about 9 miles. But later in the afternoon I couldn't make that distance (the car was in the same place) so the noise level must have gone up at home.

Yesterday I worked G7OEM/P on Arnside Knott (SOTA G/LD-058) from home, on 7 MHz SSB.
Useless SOTA fact - in 2009 45% of English chasers used 7 MHz SSB.

Saturday, 13 March 2010

Data modes interface


Here is my data modes interface, connecting a serial port, sound card and the 6 pin data socket on rigs. It uses an NPN transistor, resistor and diode in the keying circuit.

Thursday, 4 March 2010

12m WSPR

I've been doing some 12m WSPR today, it's one of the least active
bands for that but so far today I've had 2 reports from the USA.
Yesterday was 10m activity day, i only got one report and that was
from Holywell north Wales, just under 100km away.
On Sunday when I was at Claife Heights I transmitted WSPR on 6m using
my FT817 to a half wave vertical. I received my own signal at home
with -9db snr. Is 6m any good for short range stuff or is my loft
antenna picking up so much noise?