giovedì 26 dicembre 2019

Testing on the air the "Shorty Multy"

I tested for a month (from 22/11/2019 to 22/12/2019) the "Shorty Multy" on the air, to verify the possibility of making QSO with this short antenna, first of all in 40 meters. It was easy to do it, and the answer was generally the first time. On 40 meters i was QRO (10 watt); on the other bands i was QRP with less than 5 watt ( usually 3 or 2 or , 1,8 watt).

73 de IZ3AYQ

domenica 22 dicembre 2019


My new antenna used with good results on 40m, 20m, and 15m. Here is the schema.

The antenna in the origin was an OCF (off center feed dipole), of 21 meters; this is a simulation of the OCF (not linear loaded):

The OCF was too long for my balcony, so i tried a new configuration: now it is a 23,4 OCF dipole, linear loaded. The center of the cable is attached to the vertical part, that is the aluminium tube.
I use it with my micro Bitx, with 10 Watt on 40 m, 3 watt on 20 m and 1,8 watt on 15 meters with very good result (in 20 m and 15 meters i work QRP, with less of 5 watt !!!). I use a Kenwood AT-130 antenna tuner to tune it.

In the next post i will report my testing.

73 de IZ3AYQ

domenica 15 dicembre 2019


QRPx: collegamenti radio con potenza inferiore ai 100 mW. Difficile ma possibile! Molti appassionati abbassano la potenza fino a livelli di 80 mW, 50 mW, fino a 10 mW o 1 mW per collegamenti sfidanti.
Ancora meglio, costruiscono in modo minimale un trasmettitore con pochissimi componenti e bassa potenza, come quello che segue, denominato "Vanguard", di Oleg Borodin, RX3G (ex RV3GM):

Oleg lo usa con una Yagi 3 elementi, ma essendo la potenza di circa 80 mW, anche supponendo 6 dB di guadagno, che equivarrebbero a 320 mW sul radiatore isotropico (circa 4 dB di guadagno sul dipolo), è una grande sfida fare questi collegamenti.

La pagina del Club 72 è molto interessante, perchè questi circuiti sono usati e non sono solo un esercizio di semplicità:

Link al Club 72

Ci sono anche altri trasmettitori analoghi, ne documento qualcuno:

Ed aggiungo il famoso MMM (Michigan Mighty Mite):

73 de IZ3AYQ

martedì 3 dicembre 2019

Simple audio amplifier

Simple audio amplifier with TDA2003

This audio amplifier can be easily used with rigs like Pixie, or Microbitx to reach the audio output power of about 10W. Very easy to do, you can find kits for about 1 or 2 euro in the Internet. Vcc can reach 18 V.

 73 de IZ3AYQ

domenica 17 novembre 2019

Testing an Off Center Feed Dipole

I tested my new Off Center Feed Dipole, for restricted space:

- in a balcony on 5 meters and on a tree; 
- total lenght 21 meters, but folded and linear loaded.

It is a strange Antenna, but resonate easily (with a tuner) on 10 m, 15 m, 17 m, 20 m, 30m, 40 m and 60 m; with some SWR on 80 m, but with bad result on 80 m. 
In 20 m and 15 meters we have a good result; in 40 meters only a sufficient result, but you can be on the air, if you have problems of restricted space.

Tested with:

- 4 watt in 20 meters
- 10 watt in 40 meters

73 de IZ3AYQ

giovedì 3 ottobre 2019

The 1watt game

Objective: a short QRPP CW game on the 20 m band. All radio amateurs and SWL's are cordialy invited.

Date: 20 october, 09 to 12 utc
Band: 20 m,  14060 +/- 10 kHz
Power: max 1 watt
Operation: only CW
Exchange: rst + maidenhead locator (eg: 559 jn21la) - additional informations like power, rtx, antenna... is welcome.
Score: the distance in km between 2 locators (eg. 2360 km for 2360 points)
Total score:  sum of all qso point.
Log: email your score to
Add the text: me, (your call), i declare that i managed a total of xxx qso, my best result is xxx points.
Log deadline: 1 nov. 2019
Nominees: award for the winner, the best dx, funiest location (if outdoor), original home brew, lowest power.

73 de IZ3AYQ

mercoledì 18 settembre 2019

3 more QRP tx

Qrp transceiver 20 m by G0KJK
(Put 1000 ohm in series with the red led)

73 de iz3ayq