Author Archives: m0spn

Over Voltage Protection

I recently re-homed several cheap 13.8V linear PSUs from rallies, ranging from 3 to 10A. My intention is to power smaller items of equipment; TNCs, FT817s and similar. However, after inspection it became apparent that all lacked any form over over … Continue reading

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Hybrid NiMH Battery Test

Receiving a set of NiCad batteries as a 10 year old (for use in a ‘Knight Rider’ RC car – how awesome was that?!) started a lifelong obsession with rechargeable cells.  My interest in batteries started even earlier than this, after being given … Continue reading

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Chord DM01 vs Samson Q7

I’ve been very happy with my cheap dynamic mic (a Chord DM01) and have received many complementary reports on my audio.  However, having recently been asked to co-present a podcast I needed to confirm the mic was up to the job; … Continue reading

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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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