Wednesday, November 10, 2021

 3D printed Collinear ant for 2m & 70cm (APRS & LoRa)

I am playing with the LoRa APRS for some time. It is quite a funny what a DX you can have with a few mW of RF power. I had some X30 and X50 antennas and I was thinking about something more powerful. Collinear antennas are a good choice and when my friend did drawing of dipole holders for me, I could just simply printed it. Building of antenna was a question of one Sunday. There is simly drawing. 
There are STL files for 2m and 70cm version. It is designed for 30mm main pipe and dipoles are made from 10mm (2m) and 8mm (70cm) Al Pipe.

There are dimensions of the dipoles. Final SWR was under 1:1,1 at 145 MHz and 1:1,2 at 434 MHz:

And examle of instalation at OK2ZAW-17 solar powered DiGi in the Eagle Mountains 1100m asl.

Monday, July 19, 2021

 NEW parts from my

There are some new parts which I made in last month. I do have much more at the table, but I am waiting for enclosures...

Small 3-way RX splitter / combiner board:

The splitter or combiner is a very useful device. It can provide equal voltages, equal current, or equal power to matched or unmatched loads. Like all passive splitters and combiners, this device is less than ideal. Isolation is maximum only when at least one port are properly terminated. In this case isolation between the three splitted/combinated ports is maximum when the main port is properly terminated. This HW is designed only for RX line. Both impedances 50 or 75 Ohm can be selected by the jumper.

Main functions:
- Broadband: 0.1 MHz to 60 MHz
- 3-way Splitter or Combiner
- Low loss
- In to Out is typ. -5,8 dB
- 50/75 ohm impedance - easy jumper switch

PCB size = 50 x 50,4.
Aluminium enclosure size W x H x L = 58 x 24 x 50.

- Impedance 50 or 75 Ohm
- Insert loss: around 1 dB
- Split 4,8 dB, together with IL around 5,8 dB
- Isolation more than 18 dB for middle port and more than 23 dB for 1 and 3
- SWR on splitted ports better than 1:1,15 on HF, resp. 1:1,25 on 6 m
- SWR on main port around 1:1,3 on HF, resp. 1:1,4 on 6 m

- Antennas combiner - 3 el broad side array
- RX signal divider
- 10 MHz signal splitter
- One antenna to three RX

4-way PTT splitter:

This is simply 4-way analog splitter. Designed for no-delay PTT switching. From one input to 4 outputs. You can split PTT signal to 4 independent devices.

Main functions:
- Universal (PTT) switch splitter
- Minimal delay
- Compatible with 5V PTT logic (OM-power)
- 4 x output FET switch - DC 50V 0,5A
- PTT LED indicator.
- RCA connectors.
- PCB size = 50 x 50,4 mm.

Available as:
Assembled board - tested
Assembled in aluminium enclosure (blue)

- Input PTT logic compatible with 5V and more
- Input PTT logic active when grounded
- Input PTT logic current typ. 40mA
- Output FET switch 50V 500mA for each port
- DC power supply 9V to 15V typ. 65mA

- PTT for more PA
- TRX PTT to another RX and TX devices
- PTT to interlock, PA etc.

Decoder BCD to DEC (1 from 8) not only for antenna switch:

This is simply but powerful decoder from BCD data to one of eight. You can use it everywhere you have less wires than you need. You need only 4 wires and control up to 8 outputs. You can supply external relays over the BCD data wires. There is universal output driver. You can drive outputs by switching to GND or + Vcc voltage. BCD inputs include RF and high voltage protection.

Main functions:
- BCD to DEC matrix table
- Outputs 0 to 7 or 1 to 8 (jumper)
- Universal OUTPUT: + or gnd
- No external voltage needed. Up to 0,5 A by BCD wires
- BCD input 9 to 13,8V
- RF and high voltage protections
- Both drivers (ULN and TBD) are included
- PCB size = 90 x 52

- Output current max. 500mA
- Voltage drop for TBD driver typ. 0,2V for +12V input and 0,6V for BCD wires power input
- Voltage drop for ULN driver typ. 0,8V for +12V input and 1,3V for BCD wires power input
- Input voltage > 13V is recommended for 12V relays
- Control voltage for BCD input is 9 to 14V
- Low loss in switching driver
- Universal output switching: to GND or + Vcc
- Output 0 for 0000 BCD or 8 for 0001 - easy by jumper
- Compatible with Ameritron MCS-10
- RF and high voltage input protections

- Universal decoder BCD to DEC
- Compatible with Ameritron switches
- When you miss wires to your tower :)
- Remote Control expander

Tuesday, May 25, 2021

 6 and 4m MSK144 and FT8 skimmer OK2ZAW/2

There is new Es season starting on VHF bands. I have seen interesting DK8NE 6m skimmer (link) for more modes. I do have Proxmox virtual server under the roof in 40m above the ground. Why not to run one more VM, add 4m dipole with filter and LNA for RTL-SDR (70MHz) and RSP1 (6m). There are some photos. You can find spots at:

3D printed insulator for 70MHz dipole


Thursday, May 20, 2021

 Outstanding opening on 6m to NA 19th May 2021

I had big luck to be on air during the afternoon 19th  May 2021. I were able to work NA until 1 am in the morning. Big surprise was John W7CD from WA. Quick QSO with strong signal. He played for more than 1,5 hours around -10 dB signal.

I totaly made 80 NA stations during evening!

It was very nice to meet some friends. First QSO to NA this year was with Pat W5VY. Thanks for email PAt :) 

Hello Jan,

I was great to work you on 6M FT8 today!  Your Four to One QRO switch was in-line….with very little attenuation!!

73, Pat, W5VY

Thanks also to Gary K9RX and Mark K4SO.

Tuesday, February 16, 2021

OL57ZW - in memory of our friend Zdeno-san OK2ZW - CQ WPX RTTY 2021

OL57ZW is special callsign dedicated to the memory and honouring Zdeno OK2ZW (ex.OK2PZW), who unexpectedly left us on 4th January 2021, at the age of only 57 years. For Zdeno, the radioamateur hobby was everything and his greatest passion. He was an excellent DX-man, HF and VHF contest operator, who achieved many excellent world results. He was active from Accra as 9G5ZW and Ankara as TA2ZW in the past. He was also participated in several DX expeditions, where he was a brilliant operator.  Zdeno took part in more than 10 contests with us from our OL7M club.

He was also active with contest teams OL2R and OK5W.

He was our great friend and buddy, whose departure hit us hard. Please, recollect all the great memories you had with Zdeno. We will surely do the same thing...


Call: OL57ZW
Station: OL7M

Class: M/S HP
QTH: Policko
Operating Time (hrs): 48
Location: Northern Europe

Summary:   Compare Scores
Band QSOs
80: 564
40: 1306
20: 1065
Total: 2935 Prefixes 1087 Total Score 12,258,099

Thanks for QSOs - All stations will automatically receive a special QSL via the bureau.

R.I.P. Zdeno

Pavel OK1MU on behalf OL7M gang

Photos by Olda OK1YM: