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

giovedì 22 agosto 2019

Club 72

Un club interessante: Club 72

 Credevo di essere già arrivato al limite della potenza utilizzabile per effettuare QSO con il CW: circa 1 watt (non stò parlando dei modi digitali, come FT8 ed altri). Ed invece ho scoperto che alcuni OM utilizzano potenze ancora inferiori, fino a qualche milliWatt.

Esiste un Club in cui si perseguono queste attività: il Club 72, fondato da Oleg Borodin, RX3G.
Il link è il seguente:

Sito del Club 72 

Qui ho imparato alcune sigle nuove, oltre a quelle conosciute del QRP e QRPp:

QRP:   potenza < 5 Watt
QRPp: potenza < 1 Watt
QRPx: potenza < 100 mW 
QRPu: potenza < 10 mW

Altre informazioni si possono trovare su QRP Vestnik ("Messaggero del QRP"), la rivista pubblicata sul sito del Club72.

venerdì 17 maggio 2019

QRPp: slowing down the power again

QRPp: using only 1 watt

Working conditions: 
Rig: microBITX
Ant: Off center feed dipole, 20 meters long, folded and linearly loaded (on a tree). 
Ant tuner: Kenwood AT-130
Power: 1,25 watt (1250 milliwatt)

QSO during last year of very soft activity on 21 MHz (almost some minutes during the weekends; never in the evening or during the night).

 I use the microBITX from about one year. On 15 meters, the power given is of about 1 watt (1250 milliwatt).  I thought the output power was of 5 watt, but when i measured the output power i realized that it was of only 1 watt (1,25 for the precision).
So, my QSO are almost QRPp. 
During the last year the band was often closed, so i worked mostly on 40 and on 20 meters. We are during the minimum of the solar cicle, and so this is what we can expect. But last week i extracted the data from my database, and elaborated them. The strange thing is that generally when i had the QSO, it was not difficult, may be for the low noise of the band.
My favorite mode is CW, but also USB is valid, during contests.

73 de IZ3AYQ

sabato 16 febbraio 2019

The 1 watt game

I. OBJECTIVE: A short QRPP CW game on the 20 meterband. All radio amateurs and SWL's are cordially invited.
II. DATE : 31 March 2019 from 0900 to 1200 UTC.
III. BAND: 20 meter band only. 14.060 MHz +- 10 kHz.
IV. POWER: maximum 1 watt.
1. CALL: CQ 1W
2. EXCHANGE: RST report plus Maidenhead Locator. ie. 559 JO21LA. Additional info like power, RTX, antenna,... is welcome.
Calculate the distance of each QSO.
ie. QSO between locator grids JO21LA and KO92SP is 2360km. This QSO counts for 2360 points.
TOTAL SCORE: Sum of all QSO points.
Email your score to
Add the text: Me, (your call) , I declare that I managed a total of XXX QSOs, my total result is XXX points.
Please add your best DX (call and locator)station-info: locator, power, RTX, antenna. Pictures of your set-up are appreciated.
VIII. GAME REFEREE: Peter Kempenaers (ON6KZ/OO7Z). The Game Referee has the right to request full log in case of any doubt.
IX. DEADLINE: 14 april.
X: Nominees: award for the winner, the best DX, funiest location (if outdoor), original homebrew, lowest power QSO.
XI: Helpful links:
Determine your Maidenhead locator:
Calculate the distance between 2 Maidenhead locators:

73 de IZ3AYQ