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Sunday, 27 September 2015

More Testing - Starter for 10GHz


You may recall a while ago I started a microwave project called "A Starter for 10GHz" and I did some basic testing of the RX here. Today I have been to visit Peter, G3PHO and his amazing emporium of test gear; together we have tested the TX side of the project successfully.

I've done a few other things since I came back from visiting Peter - the first being to devise a way to get my DC to 1.5GHz spectrum analyser to display 10GHz signals following some excellent inspiration from Peter.

Here's a picture of a eBay purchased LNB:

This device is very high specification and uses a PLL local oscillator, here's the spec (in German) from the box:

So basically it's designed to receive 10.7 GHz to 12.75GHz with a local oscillator of 9.75GHz. If you inject a tone to the DC supply you switch to the 10.6 GHz local oscillator also available, but we don't want that for our purpose.

Now, I've made a very simple Bias-T to send some DC up the coax feed to the LNB:

and used this to connect the LNB to the input of my Spectrum Analyser:

Very much inspired by the ARRL $25 10GHz Signal Generator I purchased a couple of the HB 100 units from eBay for a few $s. I have added a voltage regulator plus a couple of caps:

This is switched on and running on the bench as is BTThing I told you about back here. BTThing is set to 2592 MHz making the 4th harmonic at 10.368 GHz.

The Spectrum Analyser screen looks like this:

The smaller peak to the right is BTThing. Doing the maths, we have:

Which is pretty damn close to the 4th harmonic calculation of 10.368 GHz.

Using a similar technique:

We can deduce that the HB100 $25 ARRL signal generator is on 10.345 GHz.

Local conditions. All good egh?

1 comment:

  1. Hello !
    Take a look here !
    I hope you can youse Google to translate ;-)
    73's Peter de PA1SDB