Tag: radio

LEFARS Field Weekend

Once again members of the LEFARS came together at the Rainbow and Dover PH near Harlow to play some radio. George M1GEO and Chris G8OCV had recently serviced a tri band beam from Cushcraft A-3S donated by Bill G0BOF to the SNB group. The event this weekend was its first field day outing, and it performed very well. The antenna worked as a 3e trapped beam on 28, 21 and 14 MHz bands.

The boom length of the antenna is just 4.17m and the longest element length is 8.45m. You can download a manual for the antenna here.

The 3e beam was supported on the 12m SCAM pump us mast, as was the 3.5MHz dipole. We also operated on 50 MHz and 70 MHz using a slim Jim and dipole.

Using 2 x Icom 7100 for HF, one connected to the Cushcraft beam, and the other on 70, 50 or 3,5 MHz. The amplifier was a solid state HAL 1200 delivering 400w to the antenna,

DCIM100MEDIADJI_0094.JPG

7 MHz was also in use giving John the chance to try out his newly acquired Icom 7300. The new Icom is proving very popular, with 3 club members recently investing in this new mode.

27904200764_4c40d3a8e2_kOver the weekend we made close on 300 QSO, and combination of CW, Phone and Data modes.

Here you can see Fred G3SVK working a few on 14 MHz CW.

You can read more about LEFARS and GB0SNB both active clubs in the Essex area

 

 

 

 

 

Second 70 MHz contest

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We had some great September weather today for the RSGB 2nd 70MHz contest. We setup a station at the Kelvedon Hatch ‘Secret Nuclear Bunker’ as seen above, using John M0UKD 70MHz amplifier and his 4 element DK7ZB 12.5Ω Yagi. The mast was my 12m Racal PU12 a push up 12m mast, and the location was around 100m ASL. The radio was the Icom 7100, as this provides all mode 70 MHz coverage.

                                        QSO map

QSO Map - 2nd 70MHz RSGB Contest

Conditions seemed quite flat, we didn’t manage to work into Scotland or Ireland but our best DX (as many others) was PA4VHF at 449km. Other highlights were GJ3YHU in Jersey and M1CJN/P in the North York Moors.

A very enjoyable day of operating and testing the new amplifier. Next week, it’s the Practical Wireless 70MHz contest, so lets hope for the same weather and some band openings perhaps? Maybe I’m asking too much

The Claimed Scores are available. Thanks to John M0UKD, George M1GEO, Dave M0YOL and Chris G8OCV for help & company!

DMR radio TYT MD-380 First impressions.

After reading a review on the @essexham website I decided to take a look at the world of DMR and the MD-380 seemed like a good place to start. The radio is available from ebay for around £100 including programing lead, software and delivery ! If you want to purchase from the UK, with support then I would suggest you look towards Taylor Made RF for around £149.

So the basics, the radio is 1w or 5w, 280g weight and is supplied with a 2,000mA battery. You can program the radio with up to 1,000 channels and will operate between 400 and 480 MHz. VHF versions are available, but most DMR repeaters are UHF at this time.

tytera2

If you decide to go down the self service route you will need to register your call sign and obtain a “unique” number. This number will need to be programmed in once you receive your radio, so the addition of a USB programing cable is very helpful.

Once you receive your DMR radio its likely to be unprogrammed and you will need to source a codeplug. These are available from various websites, and due to the number of repeaters coming online they can quickly go out of date.

UPDATE Jan 2016

The structure of the DMR network has changed substantially since I first wrote this article, and many of the codeplugs have become outdated. New codeplugs that reflect the FEB 16 structure can be found at GB7JG and GB7CL website.

The following links have been retained as they may provide updates in the future, at the time of writing the codeplugs are outdated codeplug central .  GB7DD website also contains a great deal of information on DMR including codeplugs.

You may also want to download the programing software and then review the latest firmware versions available for your radio.

You will also need to have a basic understanding of “talk groups” and you will find some information on the protocol to follow.

New to Feb 2016 was the reworking of UK talkgroups. The structure has changed, and all radios will require reprogramming. The new structure is explained in this PDF available from GB7DD website

updated_dmr_talkgroups

 

Its not possible to have all of these active at the same time, and the diagram here explains why. DMR uses two timeslots, so thats one frequency time divided into 2 and you can use 1/2 of that repeaters capacity by using one of the talkgroups.

Activity and repeaters

You can review who is on DMR and the activity levels in near real time and see the signal level and BER that you accessed the repeater. A complete list of DMR repeaters and associated coverage maps can be seen on the UK repeaters website.

First impressions

Excellent value for money, solid construction and easy to read display. Audio reports are good, speaker volume and resolved audio quality are very good. The programing software and USB cable are essential, I had no issues with running these under Windows 10.

Hope to work you on DMR soon 73 Dave M0TAZ

Affiliated Society Team Contests 2015

The RSGB run a series of contest aimed at getting clubs active as a team. This year Havering ARC had 2 active stations, one operated by Fred G3SVK and the other by Dave M0TAZ. The contest encourages teamwork, and members can operate from home. The combined score from the team contributes to the club score over the course of the year.

Fred G3SVK reports that in between other activities he completed 156 contacts. His aerial was best placed for 7 MHz, so Fred didn’t venture onto 3.5MHz.

I set myself a target of 200 contacts, and had reached that after 3 Hrs. I did a little bit of operating on 3.5MHz, but the vast majority was on 7 MHz. Using a doubt antenna and 400w, the only distraction was from Billy who decided he wanted part of the action.

 

Billy offers support.

Billy offers support.

So you want to work VK and JA on 10w ?

One answer is to to learn a low powered digital mode, CW fits the bill but things have moved on in the last 100 years and computers have provided an even better, more robust form of digital communication.

What am I talking about? No not the internet, but low power digital modes like JT65, JT9, Olivia, PSK to name a few… In this article we was going to concentrate on JT65 and JT9, like many modes its hard to know where to start, what software and what frequency should you listen to.

So what is JT65
Its a low power digital mode invented by Joe Taylor K1JT in his original paper and I quote “It is easy to show, however, that neither the encoding nor the modulation of CW is optimum. When every dB of signal-to-noise ratio counts, as it does in amateur meteor-scatter and EME contacts, there are very good reasons to explore other options. Personal computers equipped with sound cards provide a golden opportunity for experimenting with the wide range of possibilities.”

The JT65 protocol uses 65-tone frequency shift keying with constant-amplitude waveforms and no phase discontinuities. The original mode was optimised for EME QSO, but later versions JT65A, B and C had a more HF focus. The mode used in the programs we will look at is JT65A although its usually described as just JT65.

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© 2015 Dave, M0TAZ