Completing 23cm

Well,

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.

23cm Portable

Well,

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:

#GHZbands

JT4F - Really?

Well

A bit more Wednesday night activity on 23cm digital modes; last night I worked Neil, G4BRK on JT4F, here's how it looked from his end:

And this is from my end:

Now, two main observations:

1. There is simply loads of Doppler or other effects - probably due to Aircraft Scatter / Reflections
2. The report I sent was received with an additional "000" on the end - I wonder why

But the decodes of this mode seem extremely reliable in the presence of  multiple reflections - which makes it ideal for this kind of frequency.

Good, egh?