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

Wednesday, January 14, 2015

Navy radio room clock

Nostalgia? I made my own replica, copy of an old Navy radio room clock...
Just for the pleasure of seeing again a Navy radio room clock like that in my Ham shack.
 Marine distress frequencies:
Red:  3 and 9 positions indicate that there must be a radio silence on the frequency of 500 KHz, 15-18 and 45-48 minutes
Green:  12 and 6 positions indicate that there must be a radio silence on the frequency 2182 kHz 0-3 and 30-33 minutes.
                                                                             Was something like this
Added new kienzle quartz clock movement
Made a new ``laminated `` dial clock

                                                                        Painting and that it!