VK Logger Ham Radio Forum Archive

Getting ready for the test/tune day 23rd of Feb http://www.redclifferadioclub.org.au/2- ... e-day-2014.

One homebrew 24GHz horn, an ad on this forum resulted in nothing, and the items on sale on eBay seemed a bit expensive when shipping is included - so I made one.
And the full complement of VK4ES cavity backed dipole feeds.

Just some relays to add , a filter , metalwork and the Arduino

next week maybe

VK4TI wrote:Just some relays to add , a filter , metalwork and the Arduino
next week maybe

Hmm, I got one of them hiding here
What will the Arduino be used for?

73,

VK6XLR wrote:Hmm, I got one of them hiding here
What will the Arduino be used for?

sequencer , vswr protection and some other things

VK4TI wrote:

VK6XLR wrote:Hmm, I got one of them hiding here
What will the Arduino be used for?

sequencer , vswr protection and some other things

Excellent. Will be nice to see how you'll do that.

This arrived overnight from element14. The price appears to have dropped.

Mmm pie.



Most likely just end up as a weather station / internet connection instead of the netbook. But I'm also going to try the wspr beacon thingy.

Slowly catching up on the back log of projects here!

This is a 23cm 150W Power Amplifier from Bert Modderman, PE1RKI.
It comes fully assembled and tested in a milled box, and for about the same price as dicking around assembling something similar yourself.



150W on 23cm doesn't get any easier than this!
It's amazing how many people actually have 23cm, and for some odd reason, they only come out of the word work on activity and field days.

Learn more about the PE1RKI amplifier module, and follow the progress of this project at vk4ghz.com

Last item for the http://www.redclifferadioclub.org.au/9- ... e-day-2014

24GHz (QRP) mounted in box and on new tripod and freshly manufactured horn antenna. Should be a bit easier to point than the 600mm monster I tried on my first outing

Sometimes it's good to get stuck in to the old technology.

VK3FJEN wrote:Sometimes it's good to get stuck in to the old technology.

Nice!
I'm guessing Lou purchased all those parts, brand spanking new at the time?

AH! old timer humor eh?

Just getting some needle and thread to stitch my sides back up after laughing so hard.

13.8vDC 60Amp SMPS using two ex-server PSU's.... now for the front panel!




Scott
VK4CZ

Sent from my iPhone using Tapatalk - now Free

Noice kit, Scott

VK4CZ wrote:13.8vDC 60Amp SMPS using two ex-server PSU's.... now for the front panel!

Scott
VK4CZ

I am guessing to drive the 70Cm power amps?

Peter, vk5pj

VK5PJ wrote:

VK4CZ wrote:13.8vDC 60Amp SMPS using two ex-server PSU's.... now for the front panel!

Scott
VK4CZ

I am guessing to drive the 70Cm power amps?

Peter, vk5pj

No Peter... just as a 'spare' in the shack, and may replace my 30 year old DSE 13.8vDC 20Amp Powermaster kit PSUs!

(BTW the 70cm SSPA has 2 x 28vDC Meanwell SMPS's)


Scott
VK4CZ

Sent from my iPhone using Tapatalk - now Free

I made these about 9 months ago... for 3400, 5760 and 10368MHz.
Who said that "you can't make anything when you live in a small unit?"

Nice work, Bruce.

Have you measured the match on each feed? I ask because both David VK3QM and I made apparently identical 3.4GHz cavity backed dipole feeds to Andy VK3ES's design. Whilst the two feeds appeared truly identical, David's exhibited 22dB of return loss, whereas mine is only 7dB. Nothing I do will improve it, either. I tried lengthening and shortening the dipole element, made a sliding skirt for the cavity wall, etc. all to no avail. I'm especially interested in your 5.7GHz feed.

Chas
VK3PY

Nice work Bruce,

I have the same experience with these things as Chas, the 2403MHz version has best return loss at 2300MHz (pity we lost that spectrum ).

How do you adjust them for best return loss? I too tried adjusting the dipole arms and covering the slot.

We haven't lost 2300-2302 MHz (yet). Don't give up before the fat lady sings

G'day All
The dish that I am using conveniently came with a hornfeed for 2.4GHz WiFi, so there I had a reasonable estimate of the focal length.
So far the transverters that I have made are reasonably low power (100-200mW), or even less.
So I fitted an isolator in the output of each Tx amplifier (Isolators are cheap with good Return Loss), and tuned the horn feeds for maximum signal strength on receive from a weak signal sources. Given that the Isolators have a Return Loss of 20-30dB... the one on the left in the photo has 30dB R/L at 10368MHz, and the other has approx. 20-26dB R/L from 2.4-5.0GHz, and that the horn feed should have >10dB R/L, plus the loss in cabling and coax relay, the amount of my transmitted signal getting back to my transmit amplifier is in the uW range!
Also if I take into account the open circuit loss across the coaxial relay, then any Tx signal reaching the input of the receiver is small as well!
I did try measuring R/L at one time with a calibrated Directional Coupler (20dB), reversing the coupler and measuring the low-level output, but with the low levels of signal which I was using, and the extra cabling to connect the directional coupler, it didn't seem worth the trouble, especially at 10GHz.