144 MHz Backpackers and Hill toppers contest

Sunday 11th June was the #2 backpackers, hill toppers and QRP contest. The RSGB contest ran from 10 till 2 PM and had two categories 25w or 5w. I decided to enter the 25w category, the radio had to be battery powered and the power limit was 25w.

The antenna was a 9e tonna mounted on a Racal push-up mast at 6m. You can read the complete rules online.

The exchange is a signal report, serial number and then your locator, so a typical exchange may be 59, 001 in JO01DP.

I worked a couple of stations who was aware it was an activity day, but not aware of their locator. I found the best way is to look it up online or download one of the many phone apps that will do this for you. I started a little late at 10.30 as on this occasion I was operating alone.

Using the Icom 7100 and a 68Ah leisure battery I was able to operate for the complete contest. I used a small netbook to log, it’s important to find something that can be battery powered for the duration of the contest. I did have one unexpected problem, if the laptop was within 1m of the radio it did cause some QRM, interesting, as I had never noticed that before.

Conditions seemed flat, but the bands were very busy, I think this contest coincided with the practical wireless QRP contest.


Over the next few hours I was able to work 75 stations in 4 countries (England, Wales, Isle of Man and Gurnsey) The best DX was 430KM into the Isle of Man.

Thanks to everyone who took part, a really enjoyable afternoon in the sun.

Share this...Tweet about this on TwitterShare on FacebookShare on Google+Email this to someone

Interesting Condition on 28 MHz

Last night 5th June I noticed some interesting conditions on 28 Mhz. I could hear some relatively short sporadic E into Ireland and Scotland.

It’s not often you hear stations that close on that band, so it’s nice to say make the contact. The signal from Steve in Lanarkshire was 59+ at times.

Steve MM0VPY from Scotland

Peter MI5JYK from Northern Ireland

This type of propagation can be very dificult at times, with deep fades and often signals go from 59 to unreadable in seconds. Keeping the OSO short is therefore essential to maintain communication.

It’s unpredictable, you never quite know who will call next.

Lisa LA8FNA from Norway.

Just a small selection of the stations worked, others included Austria, Finland, Poland, Slovak, Estonia, Sweden, Russia, Latvia and Croatia.

28 MHz is great fun when it’s open, happy hunting.

Share this...Tweet about this on TwitterShare on FacebookShare on Google+Email this to someone

The good the bad and the ugly (Part 2)

If you arrived here without reading Part 1, it may be worth checking that out.

eBay is full of fake Diamond SRH805S antenna, so in this article, we take a closer look at 3 or these versions. Only one of these is real, as it will become obvious

Click on the images to enlarge.


eBay 99p version. A look outside and inside.


145 Mhz – 203 Ohms

433 Mhz – 57 Ohms

1.2Ghz – 4.6 Ohms

VNA plot credits @DTL

 


eBay £5 version.


145 MHz – 510 Ohms

433 Mhz – 36 Ohms

1.2Ghz – 62 Ohms

VNA plots credit @DTL

 


Genuine version £25


Picture and measurement credit to John M0UKD

The antenna provides a good match on 145, 433 and 1.2Ghz and unlike the fake versions, this would actually seem to work on the specified bands.

 

 


 

 

 

 

 


So how do you spot a fake SRH805S?

I guess you need to ask yourself 2 questions.

If you purchasing it from eBay then it’s most likely fake. The other clue is price, the genuine version would cost around £25.

If you would like to purchase the genuine article, then I would suggest you use a recognised ham radio outlet.

The fake and genuine antenna both look identical, but as you can see that’s the only thing they share.

You can continue reading Part 3

 

Share this...Tweet about this on TwitterShare on FacebookShare on Google+Email this to someone

The Good, The Bad, and The Ugly

Handheld antenna, they come in so many sizes. We could guess bigger is better, but hey who wants a 50cm whopper on top of their 145 Mhz handy.

I thought it may be interesting to put a few on my RigExper analyser and see how they look on 145 Mhz.

Let’s start with the

 

NISSEI RH-9090 – around £40 (Haydon Communication)

FLEXIBLE RUBBER ANTENNA (SMA), SUPER GAINER.

  • flexible rubber antenna (SMA)
  • 40cm long
  • super gainer, for the ultimate in gain
  • TX: 2m / 70cm
  • RX: 25MHz – 2GHz
  • ideal for airband

Seems very wideband, and has a resonance on 145 MHz, good start.

 

 

NAGOYA – NA701 (ebay £1.09 free postage)

 

 

 

  • Nagoya NA-701 SMA-Female Dual Band Handheld Antenna
    Frequency: 144 / 430 MHz
    Gain: 2.15 dBi
    Height: 206mm
    Widely used on handheld Radios with SMA male interfaceSpecification:
    Frequency: 144 / 430 MHz
    Gain: 2.15dBi
    Height: 206mm
    Connector: SMA Female
    Weight: 20g

Wideband, but probably better on 158 MHz

DIAMOND SRH805S (Ebay 99p) Further comparisons in Part 2

Super Small Fake Diamond

  • 144, 430 and 1200 MHz
  • Wideband RX

Mostly useless, unable to find any freq between 50 and 220 MHz that these resonate on. Not even as good as a dummy load.,

Unable to find any use for these, but don’t take my word have a look at the plot.

 

Stock antenna on the Icom FA S270C (£18 to £25 Moonraker)

FLEXIBLE RUBBER ANTENNA (SMA), SUPER GAINER.

  • flexible rubber antenna (SMA)
  • 18cm long
  • TX: 2m / 70cm
  • RX: Wideband
  • ideal for airband

Not surprisingly it had a nice dip at 145 MHz and was the best of anything tested.

You can read more in Part 2 and Part 3

Share this...Tweet about this on TwitterShare on FacebookShare on Google+Email this to someone

Using an SDR and VAC to Decode Data Modes

Web SDR receivers allow you to remotely monitor the radio spectrum, and phone (voice) is quite easy you just click and listen. You can also use SDR receivers to decode date modes, be that CW, PSK, RTTY, HF-DL or Olivia.

The principle is the same, you need to route the audio out of the SDR, and into your data modes decoder. This requires a virtual audio cable, you will find quite a few both paid and free version on the web. It is “virtual” because you need to connect the audio from one port on your computer to another with software.

Here you will find some free virtual audio cables (untested) or you can try the most popular (but not free) version virtual audio cable program.

So you have now downloaded your VAC, next find an online SDR like this one, or others are available at sdr.hu.

Start up the web SDR and select the frequency and mode that you want to decode. Here you can see we have centered on an Olivia signal, 16/500 on 5 MHz (5366.5)

Now you need to configure the audio IN and OUT. In my case, it looks like this. Note the WAVE IN set to my sound card, and WAVE OUT set to Virtual Audio Cable

You now need to decide what program do you want to use to decode the data. Fldigi is a good free choice, I used DM780 from Ham Radio Delux but you may also want to check out Sorcerer.

HRD also have an old free version, it is worth considering and can be downloaded here.

You will need to tell the data decode program to use the virtual audio cable as the “input” sometimes called “microphone in”

Here is my sound card setting in DM780. Note the INPUT device is shown as “Line 1 Virtual audio cable”

So we now have VAC running, and our software looking for audio on VAC. Now we need to select the mode to be decoded, here is Olivia 16/500

The signal should now decode, the text should be appearing in the box, and you can see the data signal in the window.

Remember you can decode virtually any mode with the correct software.

Share this...Tweet about this on TwitterShare on FacebookShare on Google+Email this to someone
© 2015 Dave, M0TAZ