Kako razlikovati BNC konektor za 50 i 75 oma?

Skraćena veza: https://pedja.supurovic.net/veza/8930

BNC konektor je jedan od retkih koji se izrađuje u verziji za impedansu od 50 oma i impedansu od 75 oma. Za neke primene vrlo je važno koristiti odgovarajući konektor. Kada kupujete konektor lako je, kupite onaj koji vam treba, ali šta ako imate konektor kome ne znate karakteristike?

Pogledajte kako je napravljen. Konektor od 50 oma sadrži prsten od izolujućeg materijala dok 75-omski konektor to nema.

 […]
[ ... vidi ceo članak ... ]

Napravi sam: hranilica za kolica za bebe

Skraćena veza: https://pedja.supurovic.net/veza/8879

Pripremajući se za letovanje pojavio se problem. Bebu Jakšu je još uvek najlakše hraniti u njegovoj stolici za hranjenje, ali ona je preglomazna da bismo mogli da je nosimo sa sobom.

Mama Jelena je došla na ideju da sklopiva kolica koja svakako nosimo pretvorimo u hranilicu uz jedan dodatak – poslužavnik. Naravno, tata je morao da bude izvođač radova.

Sve što vam je potrebno za ovaj projekat je jedan plastični poslužavnih odgovarajuće veličine i tri do četiri držača za vodovodne cevi iisto toliko zavrtnja sa maticama. Zavrtnji treba da budu sa ravnom i što tanjom glavom.

Poslužavnik ćete lako naći u bilo kojoj radnji koja prodaje posuđe a držače u radnjama koja prodaju opremu za vodovodne instalacije. […]
[ ... vidi ceo članak ... ]

Dunax GPN-4B antenna construction details

Skraćena veza: https://pedja.supurovic.net/veza/8733

After few years of sitting on top of my apartment building I decided to bring my Dunax GPN-4B antenna down for repair as top capacitive hat was broken. I found out that there actually no technical details about fixing it. So I went through some work of gathering such information.

First I found out that manufacturer is out of business. Antenna is not in production any more and manufacturer site is down. I asked help from fellow hams, some sent me some info they had, some sent me contact info for manufacturer.I also used my own antenna to take measurements, so finally I got quite complete details that I believe could help other fellow hams trying to repair their own antennas but also ones that want to build similar antenna. […]
[ ... vidi ceo članak ... ]

Build grid dip meter adapter coil for antenna analyzer

Skraćena veza: https://pedja.supurovic.net/veza/8706

Antenna analyzer like MFJ-259, MFJ-225, MiniVNA and similar may be used as simple grid dip meter for measuring coils, traps and capacitors. All you need is grid dip meter adapter coil which you may buy (costs for MFJ adapter set is about 30 USD) or make it by yourself for few USD.

If you want to build on your own here are dimensions of original coils sold by MFJ.

Small coil for short wave frequencies: coil diameter 15mm, coil length 15mm, 30 turns of 0.5 mm copper wire wound on PVC tube. Coil inductance should be about 3.6μH. […]
[ ... vidi ceo članak ... ]

Baofeng LiIon charger modification

My idea was to be able to use this to charge Baofeng radio in various power conditions including in my car and this voltage was a problem. I noticed comments that charger should not be connected to higher voltage than 10 Volts. So I modded charger to fit higher voltage. baofeng-charger-mod

Remote Controlled Antenna Switch

Skraćena veza: https://pedja.supurovic.net/veza/7497

As I live in apartment building I have apparent problem with setting up ham radio antenna. The obvious place to set up antenna was the roof as it  is easily accessible. Due to small space and me not wanting to make mess of a wires, I decided to use compromise vertical multiband. A friend had spare DunaX-GPN4B (40, 20, 15 and 10m) so it was obvious choice. I had to put down about 30m of coax cable to my apartment, and soon I was in the air.

Not for long I found out that I do miss 80 meter band a lot. […]
[ ... vidi ceo članak ... ]