Multi band pocket size QRP

Dear radio friends!

This project started as usual: just because I want to have a “new” pocket size QRP when climbing the mountains. So design rules was: KISS (keep it simple stupid), lightweight, do not need extra cables, batteries only just an antenna. Built in memory CW keyer, low power consumption in RX mode.

5w power with 5W amplifier is a proven solution. The rx is built with 3 pole christal filter two SA612 so it is a minimal configuration with really good performance on a SOTA walking 😀

I’m not inventor of cold water so Analog Devices DDS is in use for VFO, an arduino pro mini is the brain of the radio. Mini oled display more than enough on the front panel so let’s do it. There was lot of wooden model and time to time the was smaller with SMD devices.

The keyer is a YACK with touch sense code in another smd attiny13. The PCB is 3cm X 3cm. Touch sensors are hex-nuts on the front panel.

Pictures from first breadboard model trough signal clean up to finished radio. Pictures are missing only with installed battery, but you can easily imagine it 😉

It is working on 7,10,14,18MHz frequencies.

Thanks for reading!


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SOTA CW keyer + decoder (mini portable)

Dear radio fiends!

My goal was to have a portable CW keyer with memories beacon and cw decoder function, because I’m not a good CW operator. Of course it must be lightweight and small ass possible.

The requirement can not accept a large (or small display) and strong mechanical paddles. I decided to implement a touch keyer. Because I built lot of K3NG Arduino keyer it was in my focus, I have lot of experience with YACK, but it is not empowered with a CW decoder. I want to keep the design simple as can (KISS).

I have chosen the K3NG with touch keyer, memory, serial CLI and CW decoder option. To have a display for CW decoding I connected a bluetooth serial module to Arduino serial pins. Then my Android mobile can be the display for CW decoding and input for cw sending. An addition feature of android app is the macro function so I can use the app macro and keyer predefined memories for sending.

The keyer sending with a SMD transistor, soldered into a small piece of breadboard. One led indicates the CW receiving (DSP filtered) and another one the CW sending.

It is small an lightweight are you agree?

Thanks for reading!


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Trap antenna again

Trap antenna again.

I start to create a new trap antenna for HA7AJ Attila. The requirement is to work on CW segment 3.5MHz, 7MHz, 10MHz, 14MHz, 18MHz. Maximum power is 400W.

I decided to work with coax traps with RG58 on 5cm PVC pipe to handle the power.

The plan is the following:

and here is the implementation before poliester resin coat:

After some fine tuning it is seems good on my analyser:

Next is the 10MHz plan:

fine tuning:

Then next is the 14MHz plan

After tuning it seems on my analyser

The last trap working on 18MHz

The plan:

After final tuning it is resonnant on designed frequency:

After a problem with resin coat I must redesign and rebuild the coax traps. The new design based on RG179U cable because it was on my desk. But the process is pretty same. At the moment there is no resin coat applied only hot melt glue fixing the coax winding.

Then an ugly balun created into the feed point.

SO it is installed on my tower and tuning process continue with antenna wire cut.

It looks pretty on my tower 😉

So after final tuning it is resonant on all required ham-band.

Usual test on WSPR only one night:

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microBITX / uBITX full extra desktop radio

Hello radio friends,

I’m decided to create a desktop version microBITX radio. Why it will be a full extra version? Because there will be an orange pi PC for remote control & digital mode operations in the box. It can be used for logging, control the antenna tuner and rotator, etcetera. Winkeyer 2.3 compatible keyer will be included also & a serial connected SWR meter.
My plan is to be enough room for improvement & features implemented in the future.
So first I fount an old digital voltmeter in my garage with a super large box. I’m in rebuilding the box as a “project box”.
Nextion display worked fine on my wooden model & I loved it, so keep in this version. Extra arduino with DSP code also worked well so it will be part of this version.
My plan is to change the final amplifier to kitandparts 5w amplifier. Of course not a kit, My built from scratch. .  This plan has not materialized so far but it is on my roadmap.
First step is clean up the interior and design a new front panel.

It was only a test with power switch, and nextion display.

Near to finish. The design created with libreoffice draw on my linux PC.

Let’s put power supply in it and power on. It seems like a radio, but not it is just illusion. 😉 the interior is most empty.

Radio Panels are designed with SMD devices, but full description will be published in another post. Designed with minicircuits DBM. Lot of modification implemented so it is a HA7MAC improved version.

Some arduinos are next. Radio control & SI5351 will be on top of the others. All soldered in to development boards.

So it is time to plan the internal layout.

After hard work the orange pi PC and smd panels start to work on RX mode.

Next step is to be alive with TX. The old wooden model PA unit inserted for testing and replaced with a new board after successful test.

The box closed but the screw isn’t in because I have plans for upgrade (SDR option, change the PA with better 5W PA, etcetera).

I keep you updated. Thanks for reading!

73 DX HA7MAC Gábor

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Újabb QRP végfok

A kitsandparts 5w vegfoka újraépíteve

Kimenő szűrők után már szép képet ad. 7 és 14 MHz-en

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Nem sátor, de jó

Harmatfedél, kitelepülős, csavargós napokra. Majd később kiderül mire kell és kinek.

És még nem is nehéz..

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Lakoauto problema,15.169734

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Antenna HA7AJ barátomnál

A 2m-es antenna is fent volt és megnéztem, az analizátorral is.

50MHz-es antenna megint.

Antenna analízis:

Festés és összeállitás első lépés


sapágyház…Lassan, de halad.Antenna forgató belűlről:Árbóc alapozás után, cső válogatás:Innen indúltunk.

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uBITX my buid module-by-module


First of all I start to document it while the build is ongoing so there will be lot of update (fine tuning) and modification.
This is the first version aka prototype. It is only for developmnet I plan to build one for into backpack, one into my campercar, etcetera.

It looks now:

I have been started with microcontroller part. My build based on a chinese clone of arduino pro mini. It is employ an LCD without backlight.

Next part is an SI5351 module also from china. There is two problem with my work: loud reflection of I2C communication in the speaker. Another proble is, some HF injection because the oscillator signal goes thrugh a simple wire. The possible improvement what I plan is to change the simple wire to coax cable and shorten the I2C cables and employ ferrite on it to reduce the noise.

The quick and dirty solution to drive the relays is an ULN2003 🙂

The RF comming through a 30MHz lowpass filter. I have designed one here with following details and measured good performance:

All are minicircuits ADE1 mixers, installed on a small PCB with impedance adapter:

Next one is broadband amplifier. I created small PCBs for it, the plan created in KICAD ( All component is smd 0603. I used toner transfer method for creation. I’m not 100% aware of the licensing so plans are not published here now.

The 45MHz filter is a simple two pole chrystal now, how it shows o the upper photo. I plan to check the performance of the original ( and final commercial version ( in the future. Characteristic of filter is the following

Next is again a ADE1 mixer, and broadband amp again.

12MHz crystal filter is the following. It is an ugly weekender style installation. Design is the original, but the transformer created on a binoculer ferrite. 6 turn bifibrillar. The outcome is self explain nice.

Next is the mixer again and the AF amplifier. There is the next peroblem because the IC is hot. I can imagine some oscillation is in the background because if I change the potentiometer to maximum then lot of distorsion. Middle level is ok. 😦 Need improvement also. Another portion is I have forgotten the CW-in so need to redesign.

Next step is the amplifier part and improvements.
Will be updated soon.

Thanks for reading!

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uBITX my build

So let’s go build a uBITX from scratch.

Now I have limited free time, only just share with you the happyness of first receive, but I promiss to you I will back with details and steps and full story.

Update after 24h reception on 40m band FT8 mode. It looks nice:

And the next day it is a little better

And better again 30th May 2018


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