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 & digi 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 ampifier to kitandparts 5w amlifier. Of course not a kit, My built from scratch.
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. 😉

Radio Panels are designed with SMD devices, but full description will be published in another post.

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.

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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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ubitx végfok módosítás RD16HHF1

Az ötlet onnan jött, hogy az eredeti IRF510-es FET-el nagyon nagy volt az eltérés az alsó és a felső sávokon kijövő teljesítményben.
A meghajtás változtatása nem hozott látványos eredményt ezért kicseréltem a FEteket első körben RD16HHF1-re. (előtte volt RD06HHF1-is. A gyakori cserék miatt sorkapcsot forrasztottam be és abba mennek a FET-ek.)Ez javított a helyzeten, de kellett még pár apróság (nem a nyugalmi áram beállítására gondolok, azon már túl voltam) a két fet között lévő trafóval kezdtem “játszani”. Mivel gyakori “vas” cserékre és menetszám változtatásokra gondoltam ezért beraktam egy IC foglalatot amibe egy másikat lehet beledugni az előre elkészített trafóval.
A tapasztalatok alapján egy “balun” anyag lett a nyertes, min 2:3 menttel hozta a legjobb eredményt. Így a felső sávokon szinte mindenütt 5W közelében van a kimenő és az alsó sávokon 11W közelében. Tudom, hogy többet is ki lehetne hozni az RD16HHF1-bó, de aki ismer az tudja, hogy ennél többel nagyon ritkán szoktam rádiózni.

Fénykép a próbaeszközról. Természetesen a végén be fogom forrasztani a helyére a trafót és a fet-eket is.
Íme a teszt állapot.

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Kvarc válogatás ubitx szűrőhöz.

Válogassunk kvarcot.

Csináltam egy oszcillátort és megnéztem a kimenetét az RTL spektrumanalizátoron.
A működéshez 125MHz-el felkonvertálom a jeleket.

És a kimente:

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