Category: Construction

So many commercial and home brew constructors use Stauff type clamps for attaching yagi elements to the boom but I have until now avoided these because I hate the huge bolt holes that are typically at least 6.5mm in diameter which is sloppy even on a grossly overkill M6 bolt. Of course these clamps were not designed for making antennas but are extremely useful as they come in pretty much every tube diameter there is. So after many builds avoiding these clamps I decided to come up with a way to use them that would satisfy my exacting standards. One night instead of being able to sleep I came up with the YBB washer.

Usually instead I have been making my own elements mounts in some way or other but I am building some HF beams and it’s just convenient to use off the shelf Stauff clamps so I decided I needed to do something about this issue. I recently assembled a commercial beam that had a tapped boom so next to no slop bolt to boom but you could move the element side to side about ±6 inches or more at the ends of a 50MHz element. I had to use a square to mount them: continue reading

It’s time that the saying about sliced bread was replaced with 3D printers. They are right up there with the internet in ‘how did we manage without it’ in my opinion. For the radio amateur they uses are never ending!

The yagi below is completely assembled with 3D printed parts. Not only that it’s mounted to a 30mm pole with 38mm U bolts using 3D printed reducers and the guy ring has an integral 3D printed plastic bearing.

Not only that the DK7ZB match coaxes were precision cut on a 3D printed cutting jig. — continue reading

Having recently received my new (2nd hand) short contest callsign I was keen to air it and with probably the biggest contest in the world, CQ WW SSB, coming up I decided I would try a single band entry and build a moxon that was as lightweight as possible to use after how well my 50MHz moxon performed for me. This page describes my lightweight 20m moxon build.

First step was the trusty Moxgen application and give it the wire size to get my start dimensions. As with the 50MHz moxon I then used 4NEC2 to recalculate the sizes for insulated wire as I was using.

This gave me this predicted radiation plot: continue reading

At my location it’s very difficult to have any sign of HF antennas (or any antennas for that matter) up in the garden. I’m already using a covertly erected dipole after dark using this quick erect fishing pole mount. But I was very interested in an ATU free multiband antenna. The hexbeam is nice but too big and needing a rotator. So I looked at the G3TPW Cobwebb antenna. For those unaware this is a 5 band dipole based antenna horizontally polarised and roughly omnidirectional working on 10, 12, 15, 17 and 20m. The folded dipole style with shorting points seemed more complicated than I fancied so I looked at the simpler G3TXQ cobweb design. This filled more boxes for me, single wires nice and easy to tune and a tidy looking feed box. However, it would still stand out in the garden due to it being some strange looking (to non hams) spoked wire thing. What I decided to try was up sweeping the spreaders to make my G1YBB Disguised ultralight Cobweb antenna look like a rotary washing line as there is already one in my garden. I was counting on the neighbours not noticing it had grown an extra arm and got a bit bigger. Except when actually in use I would keep it low down like a normal washing line such as this:
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The coronavirus outbreak of 2020 put a stop to all portable radio activities so like many people I was forced to adapt and overcome and set up something at home. For non rotating mast systems I strapped a mast to the YL’s parasol base:

This worked for smaller dipoles but I wanted something a bit sturdier and the YL wanted her umbrella back! So I decided to make a new one. I thought about making something from scratch but after asking the local club members for ideas it was suggested to use a tamper that builders would bash sand down before laying slabs or bricks. A quick Google located one in stock in the local Toolstation: continue reading

This DK7ZB match cutting jig will enable you to cut RG179 75ohm PTFE coax accurately and repeatably to the length required to make DK7ZB 28ohm matches. RG179 is chosen as it is easy to work with and is best used for antennas that will only be used as part of an array, or lower power use only. It should be good for about 300W PEP on 432MHz. This jig arrangement gives you enough braid to solder to with a very short length of exposed PTFE dielectric. At 432MHz you want to be keeping your ‘tails’ short and tidy for best results.

Design goal:

Reality:

Building the jig. continue reading

THIS IS NOT A FLIGHT/SHIPPING CASE!!
This is a FTDX-5000 transport case for things like taking it to field day etc.

As the FTDX-5000 is an expensive and heavy beast I designed and made a transportation/storage case to fit it. I’d looked at what you could buy and everything was huge and heavy, increasing the size of the 5000 by a considerable amount. Something simple, low profile and low weight was required.

Images are clickable for larger version.

Below is the resulting case. It’s powder coated aluminium, adorned with protective foam so the radio never gets scratched or dusty/wet (just care fitting the lid is all required) and has latches to quickly but securely lock the lid on. Once in the case it can be carried around without fear of accidental bumps, things falling on it, kids fiddling or rain (to and from car etc).

The box is designed to enable the radio to be operated whilst still in the base, and even offers a handy place to hang the standard microphone: continue reading