Posts Tagged ‘Homebrew’

Cobwebb success

Posted 31 Mar 2013 — by Alex
Category Antennas

After what seems like a lifetime in the attic the Cobwebb ventured outside for the Easter weekend. What a weekend as well.

I put the little antenna up on the telescopic pole about the same height and the top of the Hustler 6-btv (in the background) and spent a few minutes tuning into various stations then dashing in and out of the house to swap the feeder over between the two antennas. Several dashes later and the freezing cold east wind finally kept me in doors just as 2 VK stations appeared on the cluster. At the time I was on the vertical and paid little attention to them as experience tells me that they wouldn’t be ‘in range’ with my 100w. Especially as I was at home in the st bees dip which usually strips rf out of the ether. I tuned to their operating frequency and was met with stoney silence, as expected.

Out of curiosity I did one last switch and the first station was a real 5 & 9. A few calls later and we managed my first qso with a vk. A few minutes later I bagged my second. Within a few hours I managed 7 new countries in between walking the dog and other family stuff. I can safely say that I will be making a more rugged version of the single wire Cobwebb and retiring the vertical.

Now the bands have returned to their usual quieter state it was certainly a good weekend to be on the radio

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All it needs is a title

Posted 28 Sep 2012 — by Alex
Category Radio

I found this on a scrap piece of paper at the club last night. Being a bit thick and not knowing what it was for certain I asked a few people and the response was fairly consistent.

‘Its a…errr…y’know…..that you know used to do as kits for err’

Obviously I wasn’t the only one who was a little stuck. Well I don’t know what it is exactly, but I can have a few guesses – I’ll nail my colours to the mast and suggest it is a current meter of sorts. Anyone else care to join in the guesswork with more confidence? It took me long enough to find out what brass treblet tube is!

Circuit

Ultimate QRSS kit

Posted 24 Sep 2012 — by Alex
Category Radio

The kit building is carrying on at my garage before the cold weather comes and means that it’ll be less than appealing to go in there. This time it is a seemingly simple kit from Hans Summers, G0UPL called the Ultimate QRSS kit. Ultimate because presumably the kit does more than QRSS, however the kit is essentially a QRP (~150mW) beacon transmitter for QRSS and other modes, the attraction for me is that it also generates the tones for WSPR and as well as offering the QRP transmitter it also has the ability to generate just the audio for use with another transceiver. I was drawn to it because it offers the opportunity for a little bit of experimentation. Although things haven’t quite gone as smoothly as I’d hoped for.

The list of features for such a price is quite impressive. This is taken directly from Hans Summers’ website (http://www.hanssummers.com/qrsskitmm.html). Which is well worth a visit if not for this kit.

The kit supports the following modes:

- QRSS mode (plain on/off keyed slow CW)

- FSK/CW mode (frequency shift keyed slow CW)

- DFCW mode (dual frequency CW)

- WSPR mode (Weak Signal Propagation Reporter)

- Slow-Hellschreiber (frequency shifted slow-Hell)

- Full-speed Hellshreiber

- Half-speed ("DX") Hellshreiber

- CW (plain CW)

- Customisable FSK patterns

Other features:

- 24-character LCD + two-button user interface

- User-programmable (callsign, message, speed, FSK, mode, etc.), settings stored in EEPROM

- GPS interface, for locking the frequency in slow-speed modes

- On-chip generation of WSPR encoded message (no PC required)

- WSPR maidenhead locator can be generated from GPS-derived latitude/longitude

- Selectable “frame” size, for stacked QRSS reception

- Plain CW callsign identifier at selectable interval

- Produces 150mW RF output, or AF output for driving an SSB transceiver

- Higher output power by additional PA transistor and/or higher PA supply voltage

My 30m version has been sat on the shelf whilst the good weather (ahem!) was continuing. This came to head over the weekend when I warmed up the soldering iron and started piecing it all together. The kit took a few hours to build and I would image that a skilled builder would have it all together much quicker than I could with the excellent instructions.

A box of bits

Unfortunately on powering up things haven’t exactly gone according to plan. It only seems to power when it fancies it and certainly doesn’t generate the tones as you might expect although I am receiving a carrier roughly in the right area. The other small issue is that the LED doesn’t appear to do anything visual, this may be a design feature but seems a little bit odd to me.

The (semi) finished kit

All these faults are almost certainly a result of my work, not the kit although it didn’t help having to scratch off the solder mask from the coil connections. I think the fault finding will take longer than the building in this instance but with a bit of luck it will involve some learning and there is no harm in that.

Still where’s the fun in it working first time?

Digital SWR meter final adjustments

Posted 15 Sep 2012 — by Alex
Category Radio

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Here’s the finished digital SWR and power meter kit from Radio Kits that is being used by the Workington Amateur Radio Club as a bit of soldering and coil winding practice. Not the poor lining up of the LCD screen. Shame really as the soldering was one of my better bits and that’s going to be covered up. All in all a nice kit to put together, I’m no soldering super star and I took my time so instead of it bring an ‘evening’ kit it I’d more like a ‘weekender’.

The case of the ……

Posted 11 Sep 2012 — by Alex
Category Radio

Well Dr Watson, its wobbly metal.

Enough of the Tom Foolery and down to the serious business of an issue that must be fairly common. Drilling larger diameter holes in flexible metal sheet generally found on hobby cases. Just in case you were wondering though Tom Fool (aka Tom Skelton) is apparently a ghost of a Jester at our local castle, Muncaster so here’s hoping he’s had plenty of opportunity to wander round the house and grounds with odd shaped holes in his thin sheet metal parts.

A lot of trouble I have with when its time to put a project in a case is that the 16mm hole needed for an SO239 for example causes me no end of trouble. I have tried a number of different ways to make the holes without giving a figure of 8 or elongated hole. Step drills tend to give slightly better results that piloting and increasing the bit size. I have found that the latter can easily end up with a poor hole if any vibration is imparted into the case.

So what’s the answer, well, I just don’t know. Punching would seem to be a better solution as would routing the holes but in the case of pre folded sheet I’m sure this isn’t too practical. I’m wondering if people have had better results with other ways of making these holes.