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Sunday, 30 September 2012

Artificial Ground - You What?

Well,

My chum Vince, G0ORC has been having a spot of bother in his shack. We have concluded that this may be down to RF problems and as his shack is upstairs, there is little point in trying to create an RF earth as by the time the cable gets to the radio the impedence will likely be too high to be of use.

I found this whilst rummaging on the interweb:

http://www.remeeus.eu/english/hamradio/artificial_ground.htm

And it looked like exactly the kind of thing he needed. As I have quite a collection of bits here, I had a rummage and started to make this for him:



The hardest part by far was mounting the tuning capacitor such that it's issolated from the chasis and effectively floating within the circuit.

The inductor was very scientific and involved some detailed calculations; I just found an old silicone tube and wound some wire round it:


We have configured this inside the shack of G0ORC and initial reports are suggesting that this is enabling current to flow out of the shack into a counterpoise that we have constructed.

As a starter for 10 Artificial Ground experiment goes, seems to work OK.

Fun, egh?
 

How Much Power?

Well,

Myself and my chum Vince, G0ORC headed off to the National Hamfest last Friday, following a lot of consideration I was thinking of changing the Linear Amplifier that I have here for HF work. I have been using a Ameritron 600 watt Mosfet linear, with great success, however I was wanting to be able to run UK legal limit RTTY without pushing things to far.

ML&S had a very intersting linear amplifier at the show which just took my fancy, another great re-shuffle in the shack and it's in:


The linear is manufactured by a company called ALPIN:

http://www.alpinamplifier.com

And contains a single 4CX800A tube capable of 1300W SSB and 1000W continuous CW or RTTY work. The amplifier looks (both inside and out) to be a close copy of the ACOM 1000:

http://www.hfpower.com/

I am told that Alpin are ex-employees of ACOM or something like that (I don't actually believe a word of this).

Anyhow, the amp certainly looks the business:


and it's very easy to tune, I have created a chart of the "starter" settings for my setup and you simply rotate the "load" control as instructed on the LCD display and then peak the "tune" control for maximum smoke (RF out).

There is a good review of the amplifier here from RadCom:

http://www.alpinamplifier.com/images/RadCom%20Review.pdf

The review seemed to say the right kind of things....

I've had a dabble in the CQ WW RTTY contest this weekend and have been delighted with my station performance. This is a map output from my log from this weekend, most of the contacts have been on 10M:


you can see that I have worked far and wide and the RTTY station here at G0MGX is clearly working well!

Cat's not been helping much as normal:


Good though, egh?

Monday, 10 September 2012

Your are, you're completely Loopy!!

Well,

Following some interesting reading on Top Band RX antennas, here:

http://www.qsl.net/kc2tx/

I decided I might like to have a go at making one of those.... the main reason being that my experiments with my sloper from here:

http://g0mgx.blogspot.co.uk/2012/08/top-band-what-happens-there-then.html

especially when using it on WSPR, I seem to find that I am being heard by far more stations than are hearing me.... so perhaps a different antenna for receive may help...

So here is this ridiculous concoction:


and as you can see, perhaps not quite as rigid as it needs to be....


but anyhow, it was strapped to a wooden support and connected to the wireless.... result.... local MW broadcast stations significantly weaker on this loop then the sloper, but more interestingly the noise was higher on this antenna than the other.... a total disaster!

So I decided to solder another earth cable onto the existing slopers earthy side and plant some more copper in the garden:


We will have to wait and see if this improves the RX performance...

Here is an interesting image of me in concentration mode:


Cat's weren't much help as normal:


Here the Geddy cat is asleep on my laptop keyboard - not very handy!


Good though, egh?