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Sunday, 29 April 2018

RIP Chopsey

My beautiful Chopsey cat died this morning.

He was our git bastard cat from hell and we loved him dearly.

Friday, 27 April 2018

Completing 23cm


You may recall last time, I was changing my portable setup for 23cm. Well, on my travels I found a Kuhne Electronic PA for 23cm and have installed it in the waterproof enclosure with the rest of the gubbins:

I have a 14dB attenuator between the transverter TX output and the PA input. Thats a bit bigger than I need, but I don't have anything else suitable at the moment. The G4BAO amplifier that I now have here (thanks John) is going to get utilised as a DATV amp (I think).

I've been fiddling with a cheap Chinese board with a variable attenuator on-board. You can control this using the DIP switches on board or by software. I've written a very simple bit of Arduino code and interfaced an Arduino Nano to the board using serial comms:

This allows me to step through from 0-30dB attenuation in 0.5dB steps. Really quite neat for just under £12 GBP delivered from the far east! I may decide to use this to get the transverter to PA attenuation exactly on the money - let's see.

I'd like to introduce you to the best and most useful screwdriver in my possession:

This belonged to my Father who sadly passed away just over 31 years ago:

I'm often heard muttering to myself "now where's Dad's screwdriver". If it's of interest Dad, I still use it regularly!

Local conditions.

Friday, 6 April 2018

23cm Portable


Following my changes to the 3cm and 13cm setup to become more portable, I decided it was only fitting to re-make the 23cm setup I made back here. I'll reuse the PA and the transverter.

The first stage in this project will be to create a new sequencer, much like the 13cm version, so we can switch the transverter, a VLNA and a co-ax relay.

Here's the design:

and in reality, this looks like this once built on stripboard:

I've already got a G4DDK VLNA for 23cm assembled here, and coax relays aplenty. John, G4BAO is just tweeking my 23cm 60W PA and once I have all the bits, we can mount them in another waterproof enclosure the same as the 3cm and 13cm setups.

As part of the sequencer design, I finalised my latching relay driver circuit and have finished up with this, included in the sequencer diagram above:

So this is what I have so far:

You can see the SG Labs transverter, the sequencer from above, the VLNA and the TX/RX switching - just the PA to be added.

I've tested one of my attenuators to get an exact value at 1296.2 MHz using zero span on my Spectrum Analyser Tracking Generator as a signal generator and concluded a value of 29 dB (its rated as 30dB).

So then I used this in line to my XL Microwave power meter to measure the output:

And in CW with key down on the FT-817 and 5W output, that reads 6.1dBm so we then add the 29 dB for the atenuator and I get 35.1 dBm which is about 3.25 Watts out of the transverter. It's only supposed to output a nominal 2W and 2.5W max - so I'm not too sure whats going on here.

I've set up the transverter to work with full bananas out from the FT-817 whilst on DC power, and the LEDs that indicate input power levels and output SWR are both shining green:

Here's a crazy cat of mine en route to a portable operation:


Tuesday, 3 April 2018

Finishing 3cm


Following my musings back here, I've finished the portable 3cm thingamabob:

I've moved the sequencer to be on top of the transverter box and added some surplus heatsyncs to the PA module.

I've even made a metal sheet and drilled it so it all fits on the arm of the dish.

I've also been up to Alport Heights today to test the portable 13cm setup:

Here's a clip of the reception of GB3ZME from the top of the hill:


Good, egh?

Sunday, 1 April 2018

13cm Sked


Just running a quick test before heading for the hills tomorrow for 13cm sked with @G4ASR.