A White Stick?

Well,

Been fiddling with a new antenna today; I bought it from "My Favorite Ham Store" LAM Communications. I only ordered it yesterday afternoon, and it duly arrived this morning by FedEx:

LAM Communications

This antenna is a "White Stick" made by Diamond Antennas and is designed to work on 6M (50Mhz), 2M (144MHz) and 70cm (433MHz).

As I have no antenna analyser that will work on 2M or 70cm I have attached the antenna (now it's up in the air) to the Return Loss Bridge we made back here:

http://g0mgx.blogspot.co.uk/2013/09/so-whats-happened-to-bridge-then.html

and also to a commercial Rigol RLB I have. Both gave almost identical results when using the Spectrum Analyser in SWR mode.

Here's what we see on 50MHz:

You can see a clear resonant point at 51.47MHz with a return loss of 23dB and an SWR of 1:1.15 (ish) - most excellent.

Here's what we see on 144MHz:

An almost identical clear resonant point, this time at 145.04MHz with a return loss of 34.9dB and an SWR of 1:1.03 - again most excellent.

Here's what we see at 433MHz:

Now this shows that the antenna is resonant way wider than the whole of the 70cm band - the measurements at 433.5MHz are 12.8dB return loss which is an SWR of 1:1.5 - again that's perfectly acceptable.

The antenna included a wire radial for 50MHz which I simply attached to the mast and a SWR adjustment which I just stuck in the middle.

Cats didn't help much, too busy waiting for tea:

Good egh?

Local conditions.

How much RTTY?

Well,

This weekend was the CQ WW RTTY Contest - by far the granddaddy of all RTTY contests with wall to wall RTTY signals on the bands.

I've had a dabble, and here is my log as a map:

Fun. egh?

It's a 4 hour sprint!

Well,

Last night was the BARTG 75 baud RTTY September sprint contest.

It's only a 4 hour test so even my boredom levels coped well with this one. 75 baud RTTY is quite odd really as I suspect I spend as much time thinking about what just happened as I save by the transmissions being faster. Net result is just more confusion on my part!

Anyhow, I have entered my meagre efforts into the contest, here's my log as a map:

Meanwhile, Chopsy has a new hidey hole:

And Pepper has found a transformer to perch on:

Fun, egh?

The Continuation of the Transverting Conundrum

Well,

I've been fiddling some more with my experimental 4M Transverter project.

I've built the RX converter:

This is fairly simple in that it takes the 70MHz signals from the antenna, amplifies them and then mixes them with the 60MHz local oscillator we developed last time:

http://g0mgx.blogspot.co.uk/2014/09/to-transvert-or-not-to-transvert.html

and results in a 10MHz signal at the output. I've done some initial tests on this down converter and it seems to work as expected.

The transmit side is still work in progress:

On the right you can see part of a traditional doubly balanced mixer - I've used BAT85 diodes this time for a change.

The mixer mixes the 10MHz drive signal with the 60MHz local oscillator to make the 70MHz (plus all the harmonics and also the difference). This is fed through a band pass filter, which sweeps like this:

and then amplified and passed through another filter. The second filter is also a band pass at the moment, but I expect I will swap it for an identical low pass filter I made for the RX side - the second band pass filter is no way near as good as the first for some reason.

I then need to make a linear amplifier to increase the output to about 10W to drive my linear.

Good, egh?

To Transvert or not to Transvert

Well,

Been thinking more about my antics on 2M & 4M Meteor Scatter:

http://g0mgx.blogspot.co.uk/2014/06/cq-on-them-there-meteor-trails.html

And wondering how my TS-990 would perform with transverters for 2M and 4M.

There are many designs out there for transverters, one of the best I have found are here:

www.g4ddk.com

Sam does a transverter for 2M and 4M; I have decided to join his waiting list....

In the meantime, you may recall we had a bash at some 4M kit a while ago, so I thought I would build on that experience and have a go at making a 4M transverter myself:

http://g0mgx.blogspot.co.uk/2012/06/even-more-4m-or-70mhz.html

So here is what we have so far, the "traditional" approach would be to build an oscillator for 42MHz and then mix it with 28MHz IF. Well, I don't have such a crystal so I have started with a 20MHz crystal oscillator and a frequency tripler to give me a LO of 60MHz. This mixed with a 10MHz (30M) IF will get us to 70MHz.

Here's the LO:

It's output looks like this:

and its harmonics like this:

So I need to feed this through a low pass filter, which inits simplest of forms, looks like this:

The one I have made above sweeps like this:

So this is looking like a reasonable start.

I need to make the down converter next, this will be made with some dual gate mosfets - I've ordered some BS981s which should perform well at these frequencies. Hopefully they will drop through the letterbox any day soon.

Cat's not been helping much at all today:

Good egh?