........https://www.qrz.com/db/F6EUQ............................https://www.qrz.com/db/VE2EK .................https://www.qrz.com/db/9Q1EK.................... https://www.qrz.com/db/ZS1II

Wednesday, September 8, 2021

ZS1ii DXCC QO-100

   03 July 2019 to 17 October 2021


DXCC = 111 countries

TNX to all


Pile up on QO-100 with Marija  YU3AWA

1st tests with 80cm offset dish + helix + LNB, Pwr SSB = 10W
Experimentations in DATV mode
 1) Dish 1,8m on test + poty feed + LNB, DATV Pwr = 10W

2) Dish 1,8m + Poty feed + Down converter Kuhne, DATV Pwr = 70W
Tests with Down converter KUHNE put in box
Tests with Power Amplifier from F4VSG @ 70w Output
No excess temperature, remains warm ( Abt 38 deg C) after 10 minutes tune.
and good linearity  
The measurements provided by F4VSG are compliant. I found the same values. Excellent Power amplifier.


Thursday, September 2, 2021

BG7TBL Noise source Modification


                                   Version 2016-03-06 Named ''Nose source''.

The PCB circuit received is clean and of good quality.

I will not go back over the various opinions, tests, modifications already made in the past. I'll just experiment with a new approach to modify it.

 Because there is a heat problem which seems to be a recurring one with this noise source.
 After a short amount of time, I can see this heat problem., The three amplifier semiconductor packages and resistors become very hot and will have a limited life span due to excessive heat.

** And more
• Don't like 24V Zener diode powered by the MC34063A (despite R11 to limit the voltage)
• Don't like MMIC's powered by 12Vdc unregulated (despite R8 / 9/10 to limit the voltage which can vary at the input).
• Output noise of the Zener source is very high
• Output after three stages of MMIC too high.
• Power density of noise is not flat towards high frequencies.
• MC34063A output is not as well filtered
• 12V DC input is not regulated.

•    Then, some modifications will be made for tests.
- Powered in 12 VDC with New system on 5 Vdc power supply (regulator 5V) for MMIC'S (5v) and new zener diode.

- Input DC connector removed
- I don't use the converter 12 / 38v MC34063A (output is not as well filtered).
- L2 removed
- Zener diode replacement by a 5V and also tests with a BFR34A / BFR93 transistor
- New DC power supply with 7805 TO-220 for 3 X MMIC SBB5089Z = +5 V and zener diode.
- Addition of 10dB attenuator on output. (replacing of the 3 DB)
- R11 must be adjusted value 1 to 3k (depending diode/RF transistor).
- Installed in metal case.
- Waiting for SMD Ferrite Bead  inductor to replace L3/L4/L5
The diagram below is worth less words… !!!

1st remark: At 1.5 Ghz, the curve is flatter, but the signal at higher frequencies decreases slightly. Still very usable for the quality and low price for an amateur.

 (Later, some pics and probably other experiments ....)

** Update 11/09/2021
Even being in a metal case, there are self-oscillations, especially around 2.4 GHz !! it's embarassing for the WI-FI or 13cm band.
To dampen the oscillations or try to eliminate them, I added above the PCB, under the metal cover and on the 4 sides, an RF EMI ABSORBING SHEET.
The noise spectrum is even flatter and elimination of oscillations towards 2.4 Ghz.
I also replaced the L3 / L4 / L5 chokes with SMD Ferrite Bead inductors.
There is still too much signal even after changing the attenuator from 3 to 10 dB.
Before trying to remove the last MMIC, I added a 10dB on the SMA output. 

(Original Schematic  is from Alyx, Dodgy Engineering  Rockville, MD)

Wednesday, June 9, 2021

New toys in the lab

 Some essentials accessories have entered in the lab after good auctions. Used but with Calibrated Certificate.
Now, enough equipment (Maybe !!!!) for my measurements.
Wattmeter Slugs - HP437B - Sensors: HP 8484A  HP8482H - HP 435B + Accy's

Wattmeter slugs



Friday, December 25, 2020

QO-100 13cm Inter Digital Filter

 I have a  NMRF 2450MHz Band-pass Filter Central frequency: 2450 MHz for WiFi.
and I found loss:
2.400 Ghz = 5.2dB , 2.409 Ghz = 4.7dB.

I have also couple of WI-FI around me near 2.450 Ghz and this BPF is is not effective..
So I'm not satisfied with the BPF NMRF 2450, I tried to made a new one on 2,4 Ghz for QO-100.

Several months ago I built 23cm Inter digital filter  for 1296.2Mhz with succes (0,85dB loss)
But with my homemade new 13cm BPF,  I have about 2.7dB Loss between 2.400 to 2.409. Not really satisfied again, I have to start experimenting again.

(Inspired by DD1US, DL3NQ and VK3UM  Inter Digital Filter Design) 



Thursday, December 24, 2020

#3 DATV QO-100 project

Heavy damage to my dish due to violent and strong winds on the hill.

The dish suffering, it needs repairs and reinforcement after the lull. 

Today, Repairing. Use of large washers and galvanized wire ties. It seems to be solid! we'll see next time!

I took the opportunity to check that the feed Poty / LNB are in the axis and in the center of the dish. Results, Hey No, not on the center. So I use the old method used many years ago. A pipe installed and blocked on the feed attachment. Perfect now! Next Wednesday, re-installation of the dish.

Gain and Beamwitdh of my prime focus 

 Distance from my house in St Helena Bay, South Africa to Es'hail-2 is 35,780.55 km.



               Some countries contacted in CW/SSB from May 2019 to August 2021