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Saturday, 25 June 2016

New Amplifiermabob


I've been thinking for a while about upgrading the amplifiers I have here for 4/6M and also 2M. Here's the result of my investment:

The 950 deliveres 1KW on 6M (500W on 4M) and the 1000 is 1KW on 2M. Both solid state amplifiers from Beko in Germany.

Given the termoil on the currency markets as a result of Brexit - I might have just timed this right.

Local conditions.

Sunday, 19 June 2016

I've made another one!


You may recall the recent Frequency Reference that I made, I've just finished building another one for someone else! This one is almost identical except I have included a 1MHz low pass filter as this one will be configured to have a 1MHz fixed output.

Here's the 1MHz output:

Good, egh?

Friday, 3 June 2016

RTL on HF? no way!


I read with interest an article in Practical Wireless from June 2016 describing a neat looking receive converter to be placed up front of an RTL dongle type receiver.

These RTL devices are easy to find for a few GBP:

Here's the schematic of the converter:

And its built on a PCB from OHS Park which cost a staggering $5 USD for 3 including postage to the UK. They were delivered in a very timely manner too! 

You will see that I have actually built two - but basically we have a 50MHz oscillator and a mixer, so in the example below my SDR would be tuned to 70MHz and I would be listening to my signal generator on 20MHz. The output contains what you would expect from a mixer in that we have the input frequency, the on board oscillator frequency, their sum, their difference and all the other harmonics from this mixing process:

More to follow once I have it up and running with the RTL dongle, but so far so good!

Local conditions.

Monday, 30 May 2016

4M - Alive and well?


Some interesting propagation on 4M today. A beacon very loud from JN86:


Here's the 4M map from the great

Definately experiencing some "local conditions"

Good, egh?

Friday, 20 May 2016

Frequency Reference Completion


The project from last time is even in a box now:

Good egh?

You will see that we adhere to strict rules whereby the dogs are not allowed on the furnature:

Local conditions.

Tuesday, 17 May 2016

More Frequency Reference


Following my musings last time over the QRP Labs GPS module, I've now also built two further kits from QRP Labs. The S5351A Module and the VFO.

When you combine all these together in the way I have you can create a GPS disciplined frequency reference with two outputs.

One of the outputs can be fixed in the firmware and I plan to put mine on 10MHz, I've made a low pass filter for this output to clean out the harmonics. The other output can be user set to any frequency up to about 290MHz or so.

Here's the LPF for the 10MHz output:

And here's the 10MHz output before the LPF:

and after:

All good, egh?

Sunday, 15 May 2016

Frequency Reference


Been thinking for a while that my shack frequency reference is a bit old hat and could be a bit more useful. What I would really like is a GPS disciplined VFO so I can set the frequency for my needs rather than only having 10MHz, 5MHz and 1MHz outputs as I do from the old project here:

So I have started to look at the possibility of using a newer device like the Si351A from Silicon Labs.

The first part of the project will be a new GPS receiver to give us the 1pps signal we need for the frequency control. I found a really neat kit at QRP Labs

I've built the kit today and it looks like this:

Mine has been built to utilise an external active GPS antenna.

The output from the 1pps looks like this on the 'scope:

So all seems well with the first phase.

More to follow!

Here's our Pepper Cat who has been almost completely in the way most of today:

Local conditions. Good egh?