Friday, February 23, 2018

Satellite Yagi crossed 2m, 70cm

Just for fun. Construction of an antenna for experimental satellite communication, 8el. (435 Mhz) x 4el. (145 Mhz) Satellite Yagi crossed.
No difficulty to built this antenna. Except the gamma match that requires a little more attention, but with the informations provided by Alex, XE1MEX, and Rob VK2GOM  (link below) it works very well. Adjustments are easy to adjust.
The bandwidth is very wide on both QRG's.
Without waiting .. Hi, 1st test after adjustments, heard S0-50  59, but duplexer must be checked..(easy to do it).

Almost ready.. ! Not very beautiful, need some improvements for the aesthetic, but the measurements are excellent, So now ... waiting for ISS or a satellites pass above..
I recommend this construction 73 ZS1II

*** 25 Feb 2018 ***Duplexer repaired. The antenna works wonderfully with the Alinco DJ500.  First contact from St Helena Bay locator JF87XF on AO-91 satellite with Tom, ZS1TA and heard many other ZS stations.
Must do fast, pass duration only 11mn...
Dipoles are alu pipe dia. 12mm, élements rod alu. dia 6mm, Boom square 20mm

Coax is 10DFB, perfect match in the alu pipe.
Inspired by:
 VK2GOM  Rob – international HAM magazine HAM-MAG April 2010  No 15
A 70cm/2m crossed satellite antenna

04 March 2018 -Simple portable Setup and homemade antenna work fine.
I prefer to use the tripod. It will also be necessary to connect a MP3 recorder because is it not practical to note the call signs, the QSO's, and to hold the antenna to track the Sat's.

Tuesday, January 30, 2018

23cm Interdigital filter

I'm on the way with 23cm station for the EME and the first small filter built in May 2013, did not satisfied me about performance, (1.25 dB loss).
So I decided to built a new one for 23cm band. After some searching on the internet, I found the following drawing of an interdigital filter from Daan PA4DAN.

As I get a lot of aluminum parts, After a quick look in the garage, I found exactly the main piece of aluminum that I needed. Inner section 54 x 28mm.
The rest of the pieces are easy to find.
Hop. Cutting, drilling, tapping and ... settings on the spectrum analyzer.
Surprise! In less than 15 minutes the result are visible on the pic ... beyond my expectations !!
1296.1 Mhz = 0.85 dB, and a very narrow bandwidth.
Look at the picture ...
A nail polish stamped at XYL to block the screws and finished!
I am really happy with this home made construction.

Results of the new one
First Filter
Results of first filter

Saturday, December 2, 2017

Small Gadget for my Lab

Too much wind today, impossible to work outside, so go to the workbench.

to built a small gadget quickly made for my little lab.
My multimeters measure at 10A DC Max, and nothing to go higher for the setting of my LDMOS amps. So, Hop! Go... search into the drawers of 4 displays (although I do not like the digital) and 2h later it's OK. et VOILA !

Thursday, July 6, 2017

Homemade. Mods of tower

Finally, after long months of research, I finally found a 12m small tower very light with 4 sections of 3m.. But must be modified.
Especially the reinforcement which was not strong enough to support a beam 11 el. HF and an el. 6m.
Redoing the arc welding after more than 30 years is not easy. But with a few tries, the helping hand came back!
As soon as the reinforcement is finished, with spacers and braces, I will try to install a sliding trolley along this tower.
More info soon !! I can not wait to be QRV ...
27 August 2017 two sections done

The Top Before
The Top Finished

Monday, August 15, 2016

Beam HF 5 bands interlaced

On the bench… Construction of a Beam HF 5 bands
Inspired by JK Antenna (JK NAVASSA-5) & Optibeam (OB11-5)
(Updated on time... More development & measurements later)

July 2016: 9 Elements, 5 Bands / Multiband Yagi 10, 12, 15, 17 & 20 meters on a 5,1m boom.

August 2016: I added 2 more el. as 11 Elements, 5 Bands / Multiband Yagi that interlaces 10, 12, 15, 17 & 20 meters on a 6m Boom.
73's de ZS1II
Balun 1:1   -   2 x FT-240-61 core
Modification U bolt, before and after !
Transmission Lines & Balun Assembly