Author Archives: m0spn

Adventures with Software Defined Radio

Some time ago I purchased an RTL ‘TV’ USB tuner. I was immediately impressed by the way whole chunks of the RF spectrum are visualised; tuning as simple as clicking a signal of interest plus ‘brick wall’ filters by the drag … Continue reading

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Multi Band Slinky Doublet

Designing an HF antenna for Swindon Makerspace presented several challenges:- Routing coax from Makerspace to the roof is potentially tricky High external vertical antennas would require lightning protection No convenient external earths available Counterpoises impractical due to size Large horizontal … Continue reading

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Introduction to Packet (ax.25)

When starting out with packet I found it difficult to find my way.  Several resources exist online but all seem to assume some basic level of understanding, which I clearly lacked.  I have to admit here, I’m still new to … Continue reading

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RSGB Xmas Cumulatives Contest 2015

Determined to take part in the RSGB Xmas Cumulatives this year, I worked from home on 3 days using completely inappropriate antennas.  On 26th December I spent 2 hours hunting around 6m, making only one contact using a dipole antenna. … Continue reading

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Studio Mic (Balanced XLR) to FT847 (Unbalanced) Input

I’d previously simply connected half of the balanced XLR mic output to the mic input of the 847; I was aware this wasn’t ideal (and I’d lose the benefit of a balanced mic cable!) but it worked and I’m ultimately … Continue reading

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Raspbian (Debian) Jessie and TNC-Pi

So, Raspbian has been updated to Debian Jessie;  we’re now in systemd land and the provided instructions from the tnc-pi instructions are no longer relevant. After installing Raspbian I recommend extending your partition / filesystem to fill the space available … Continue reading

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UK Foundation Licence Power Limit

When I progressed through the licence system over a decade ago I was taught that the foundation power limit referred to power measured at the radio, not the antenna.  This was different to the other licence classes which specified power … Continue reading

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Amplifier PTT Buffer Schematic

I’ve been keying my KW1000 linear using a relay to buffer the FT847.  The FT847 closed a 12V circuit across the relay and the relay in turn keyed whatever voltage/current the linear requires.  The relay in the KW1000 is old, large … Continue reading

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Simple Fan Dipole

After starting life as a fan dipole, my home antenna was later converted into a single 40m dipole due to unwanted interaction between the bands (at the time 40/30m).  Recently, the need to operate multiple bands made me reconsider my … Continue reading

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Simple & Cheap Speaker Upgrade

This will be a very brief post but I thought it too good not to share.  For some time now I’ve had my FT847 in a less than ideal position meaning I’ve either had muffled audio from the internal speaker … Continue reading

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