WELCOME TO THE SHACK

click on a pic for a larger view

Main HF rig ATU and 400 Watt linear along with other stuff.	Eventually this will be the work bench and test gear area	The beginning of the test gear area
400 Watt linear amp	A mess	Another mess
Beginning to look good

AF signal generator

Marconi AF power meter

MARCONI TF995A/2 SIGNAL GENERATOR - 1.5 to 220mHz

This piece of equipment was given to me by Frank, a local radio amateur. The first fault I tackled was the horrendously unstable RF oscillator. Monitoring the output on my HF receiver was like listening to chirping birds. The OB2 stabilizer (stabilizing about 105 Volts to the oscillator) was flashing on and off - not a good sign. I tried a new OB2 but it made no difference. The problem was that the thing wasn't being supplied with enough volts to strike and stabilize the HT rail. Rather than a dropper resistor on the AC side of the valve rectifier, there was a 0.25uF capacitor. Yes, capacitors can be used to drop AC voltage. Don't ask me how, but they work. So, I ripped the capacitor out and replaced it with a wire wound resistor. The stabilizer fired, the HT rail was OK, and the oscillator was a damned sight more stable.

The second fault was no modulation, AM or FM. Using the scope, I discovered that the audio oscillator wasn't working. Using my Avo, I then discovered that there was no HT on the anode of the oscillator. A 10K resistor supplying the centre tap of the anode coil was burnt up and open circuit. Why? After some poking about, I found a 0.002uF capacitor had gone short circuit. Lucking, the anode coil hadn't burnt up along with the 10K resistor. The result of replacing the 10K res and the .002 cap was that I had AM - but no FM. The FM fault was simple, a dirty valve base.

Things were looking good at this stage, except that I had very little RF output on any of the frequency ranges. Over the years, component values had changed slightly. The problem was resolved by adjusting the small trimming capacitors for each multiplier stage. The sig gen now works pretty well, but I really need to change all the .1 caps along with the .01 and .002 caps. This is an easy task, but where the hell you you get caps from? They are like gold dust these days, and they cost as much.

Test gear being added to almost weekly

There are only a few photographs of the shack which, as usual, is a mess. The AMU (aerial matching unit) looks a mess but it loads my end fed wire on 160m and 80m with no problems.

To take the above photograph I had to wade through empty beer cans and overflowing ashtrays. You think this is a mess? You should have seen it before the spring clean! On the shelf to the left, there’s the Yaesu FT1500M two metre box. Next, the Alinco 70cms box followed by the RF ammeter and homebrew ATU. Fixed below the shelf is the PMR rig modified for two metres, monitoring GB3SR, our local repeater. On the desk is the Kenwood TS-50 and the computer interface for DATA modes. Then there's the morse key and the KW 107 ATU.

The L-match, above, may not look much but it works extremely well. I cringe when I hear people saying that they’ve bought an expensive matching until only to find that it won’t load up a short length of wire. I heard a chap the other day complaining that his costly ATU wouldn’t load up his end-fed wire on top band. All you need is a variable capacitor and a roller coaster or tapped coil, and you can match any length of wire anywhere between 1 and 30mHz. I’ve loaded a 12 foot length of wire on top band perfectly. It’s not much good as an aerial, but I can get the SWR down to 1:1 Click on the above picture for more on this design.

Above: The latest L-Match for top band only. This loads around 200 feet of wire, and works bloody well from medium wave to... Yes, well. The less said about that the better!

The HF aerial management system. OK, so it's a couple of switches in a box! The aerial management system consists of an aluminium box containing a couple of pretty good ceramic switches. Pissed off with continually having to pull the radios out and fiddle about with a million PL259 plugs, I constructed the AMS. The box is rather large but I wanted enough room for more switches and or relays at a later date.

Build your own AMS! I’ll email you the circuit diagram and constructional notes for a small fee of £50.

The latest addition to the shack. The KW 107 Supermatch. Now this really is a brilliant piece of kit. With no baluns in sight, it's a truly balanced ATU. Click on the pic for the KW-107 manual and circuit diagram (pdf format).

The above photograph shows my desk and the main keyboard, where my serious work is done! The keyboard to the right is for the amateur radio stuff, RTTY, PSK31 etc.

It wasn't until I took the above picture that I realized what a mess this is. What the hell? It all works! The box with the decade switches is an old PMR rig on 2 metres. I use this for monitoring the Brighton repeater, GB3SR. The main 2 metre rig, top left, is a Yaesu FT1500M.

Another shot of the mess. I sometimes look at pictures of other people's shacks, on qrz.com, and marvel at their neat set ups with all wires and cables hidden. Does my messy shack somehow reflected the real me? I wonder!

One or two cables to sort out...