All posts by smithn

The Shack – Ham Radio 2016 style

Another G4DDK VLNA on the workbench.  13cm this time…..


Remember the “Shambolic Shack” feature of the 1980s? Is this just a slightly higher-technology version?  This is the Engineering side of the G4DBN radio room, the operating position is to the left.  Repaired Kuhne 13cm transverter and Anglian 144MHz transverter on the operating table in front of the testgear rack


DB6NT MKU 23 G4 13cm transverter

Another new toy arrived today, the latest 13cm multi-segment transverter from DB6NT

Feels very solid and precise, reassuringly heavy

onnected to the DDK Anglian transverter

IMG_0426Output spectrum, 20dB attenuation external to the 8562A, so 27.17dBm output on 2320.200MHz.  Close-in noise about 80dB down at 5kHz.  The HP436A shows about 27.8dBm.  Second and higher harmonics are below the noise floor of the analyser.

2320 spectrum MKU 23 G4This is the SDR waterfall with a -156dBm carrier in to the 2320MHz RX input from the E4421B via a Narda 18GHz 20dB pad.


Binocular Microscope

I finally cracked and decided my eyeballs were not up to SMD work, and holding a magnifying glass was just too clumsy, so yet another bit of kit has appeared.  7x to 45x binocular microscope from AmScope. Very nice working distance and excellent clarity, at full zoom an 0805 resistor looks like a house-brick.  FOV at 45x is about 4mm. At 7x zoom, full frame is about 25mm diameter, with 100mm working distance.


13cm Spectrian amplifier

I bought an eBay Spectrian 75W amplifier for 13cm to go with the Kuhne transverter.  Spec says 26V at 16A, so the efficiency is extremely low, but it was cheap.  7 amps or so standing current. Thinking of watercooling it.  It has a thin copper heat spreader bonded to the underside of the PCB, so maybe OK just mounting it on an aluminium cooling plate, but I have a bit of copper bar that I can solder the water pipe to directly, so might go for that instead.  Transverter has not arrived yet, so having to test it with a CW signal from my Agilent E4421B



144MHz Anglian transverter

After seeing the Anglian on Sam G4DDK’s stall at the Martlesham Microwave Round Table event, I bought one of the last of the batch and built and tested it as the IF for the upcoming 13cm and 3cm transverters.  Great fun and it works extremely well with a 116MHz GPSDO locking reference at -10dBm.  Output is very clean at 13dBm output, and receiver is performing as per spec.


23cm PA project

The parts are coming together.  Nice isolators direct from RFCI in CA, peak 1kW, 200W continuous, built in 100W dummy load



FETs. At six quid each, the MRFE6S9160HS makes a nice cheap 23cm PA, cellphone technology instead of broadcast devicesfets

Hybrids. OK, I could use a printed Wilkinson as the input splitter, but hey…


Relays. The R570113030 is rather over-specified for this, but has 85dB isolation up to 1GHz and 80dB up to 2GHz and should handle up to 500W at 23cm very easily.


Tinplate boxes to screen the individual DF9IC PA boards


27V 18.6A switchmode PSU