The Ham Shack home made accessories

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Audio Monitor

I built this item so I could switch a pair of headphones between up to six radios in the shack and perhaps switch the audio from one radio to the audio inout of another radio to run the Sunday morning broadcast sometimes when I am needed. The six inputs come from the six speakers on the control panel and use isolation transformers between the radios and their external speakers and the two selector switches you see on the box. Each input is wired to two six position rotary switches, one switch each for the right and left headphone. The outputs of the switches then go to two switchable high pass and two lows pass filters. These are Jaycar kits. The outputs from there go to a volume control for the phones and to two sets of RCA connectors on the rear panel for recording on a computer via two more isolation transformers and to a digital note taker. They also go to a four position switch that could provide signals to radios if I am ever called upon to originate one of the local WIA broadcasts. The headphones are driven from a Jaycar headphone kit. The front panel was getting a bit crowded to each switch has a row of LED's to indicate which position it is switched to.

when I first built this box I used a conventional "E and I" style power transformer but this induced too much hum in the isolation transformers. I replaced the original transformer with a toroid mains tranformer and the hum is now at an acceptable level. I may one day remake the power supply (plus and minus 15 Volt rails) with a supply from my 12 volt shack supply but it will have to be a very quite switch mode.

BoatAnchor selection switches

BoatAnchor antenna selection switch one

This first box provides microphone and press to talk switching for up to five BoatAnchor Transceivers and has outputs for DC control signals for each of the five positions. A Phono Jack is provided to connect a foot switch for PTT if desired.

I built this box with five four pin DIN sockets for the cables to the individual Rigs. The 12 Volt outputs are provided by the RCA sockets. After I built a four position relay box to provide more microphone selections from the 12 Volt DC output from the coaxial switch below, I decided to change the connectors to four pin microphone sockets so the cables would be all the same for each microphone to Rig lead. I also removed the 50K to 600 Ohm transformer from the Redford/Foster/Yaesu desk microphone, yes the same item is sold under there three names.

I then added switches to the back of the box, wired to the 12 Volt control output, and this operates two relays. These switches are centre off three psoition. In the centre position the microphone output is high impedance via the 50K to 600 Ohm transformer now fitted in this box, in the down poistion it is 600 Ohm and in the up position the lower eight pin microphone socket for an Electret microphone is selected. The lower toggle switch configures this microphone socket to either Icon or Kenwood configuration. The fifth output socket is an eight pin socket and is a work in progress. The selector switch below this socket is a 3.5mm stereo socket and controls the two relays in "position five". Position five hands over to the four position coax switch.

BoatAnchor antenna selection switch

In addition to the five position BoatAnchor selection switch there has to be a coaxial switch to select which radio is connected to the BoatAnchor position (Position Five) on the above switch. I was lucky enough to be given this very fancy four position BNC switch and I have put it on the back of a diecast box and fitted an Oak rotary switch wafer to the shaft to provide other switching possibilities. This switch is mounted to the top of a Heathkit HM-102 SWR/Power meter. The output of this switch goes to the Antenna switch panel and there is a CX-201 coax switch that selects either a dummy load or the rest of my antenna switching. This allows me to tune up BoatAnchor radios off air and when I am satisfied they are working properly I then switch over to an antenna to go on air.

BoatAnchor selection microphone selection box

This one is controlled by the four position coaxial switch and switches a high impedence Yaesu desk microphone to one of four BoatAnchors and

SlignaLink USB transmitter interface

Soon after I started to experiment with WSPR I found it quite difficult to adjust the TX and RX level controls on SLUSB and anoying to have the sound of the received signal which was not even detectable above the background noise comming out of the speaker. The Kenwood TS-50S that I use does not have an auxilary port like modern rigs and I have to take the audio from accross the speaker and feed the transmit signal into the microphone input. I had already made a simple switch box to switch from mormal microphone use to digital modes so it was not difficult to modify this interface by adding pre set level controls and a DC output in digital modes to operate a relay to mute the speaker. When I built the box I could only find a three position switch so now I could make use of the extra position to either mute of un mute the speaker in digital modes.

The speaker mute lead supplies 8 volt DC (the 8 volts that normally powers the Electrec microphone insert) to operate a relay in my antenna control panel via a swithcing transistor. This interface box also has several DC jacks including a lighter socket to power other devices in that area.

I decided to put two muting circuits in this box as there was plenty of room.

SGC Smartlock control

In the hand book to the SGC SG237 Auto Antenna Tuner there is a circuit for an interface they call the SmartLock and it allows some manual control over the AATU and more importantly, it indicates when the tuner has tuned successfully.

VK PowerMaster

This started life as a kit from the old Dick Smith stores but it came to me in poor condition. The DC out terminals on the front panel were melted, they had not been up to the 20 or so Amp it could deliver and two of the 0.1 Ohm current limiting resistors were open circuit, limiting the output to about 12 Amp. I replaced the output terminals with an Anderson connector on the front panel and installed lighter and accessories power sockets on the back. I fitted a larger fan with a fan switch and a current meter with ranges of 5 and 25 Amp. I also added a 240 Volt circuit breaker and a reset switch with a high power bleed resistor, from the later version of the circuit. The original versions of these power supplies take a long time to reset when they trip and this overcomes that problem. I added a cirarette lighter socket and a common "Merit" 12 Volt accessory socket to the rear.

There were three versions of this power supply featured in Electronics Australia, here are the project files for each of them:
The 1984 version
The 1990 version
The 1993 version

An addition to the shack is a rebuilt vintage VKPowerMate power supply

This one came to me via a friend who was "down sizing" and it looked as though it was built from a Dick Smith kit by a "Harry the Ham". I cleaned it up and added a simple digital volt meter, put the voltage control on the front, added two current monitoring jacks to the back (these have a 0.1 Ohm resistor in series with the positive output lead) added two 2.5mm DC power sockets and two 2.1mm DC sockets supplied by a five volt regulator and a cirarette lighter socket. I am going away from using these and fitting Anderson and Power pole connectors to my equipment but I still have some stuff fitted with these connectors so I can use them as a a replacement for my "Jump Start" battery to operate a modified chordless drill and other items.

There was two versions of this project published in Electronics Ausyrslia, 1978 and 1983:
The 1978 version
The 1983 version

12 Volt DC Power Stations

Much of the equipment in a modern Ham Shack operate on 12 Volt DC so in addition to the VK PowerMaster I have an 80 Amp Hour battery kept charged by a multi stage charger that generates quite a bit of RFI and so it has to be turned off when I am operating on HF. In the rack at the operating position I have what I call the VK5SRP Power Station. In addition to the 3.5 mm DC sockets supplying 12 Volt through 3 Amp fuses, there are two 3.1 mm DC sockets supplying 5 Volt. In the rack on the other side of the room I have another smaller "VK5SRP Power Station Two". This also doubles as a field day power distribution box.

In addition to these two I have two other 12 Volt DC distribution boxes, the one inside the antenna switching panel with speaker muting relays (pictured above) and another in a rack with some for the communications receivers. This one also has 3.1 MM DC sockets supplying 5 Volt.

10 MHz frequency standard

I was given two Oak 4884 OCXO modules some time ago and while looking for data I cam accross several web sites with details of using these and even more interesting web sites describing how to use Rubidium standards that were available on Ebay for as little as US$45.00. A quick Ebay search did not turn up any that were that cheap so I setup and Ebay search and waited for one to find me. Sure enough after several months I bought an FE-5680A Rubidium Frequency Standard for $40.00 with $10.00 postage. These things are recycled from Cell Phone equipment that is sent to China for recycling. I had a suitable cabinet left over from a past project at work so I built a power supply into that and put both the 4884 and the 5680A modules in that.

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Written by and Copyright, Phil. Storr © Last updated 25th December 2015