More Coax, SWR, Dummy Loads and Technicians pool questions.

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George Thomas, W5JDX, is co-host of AmateurLogic.TV, an original amateur radio video program hosted by George Thomas (W5JDX), Tommy Martin (N5ZNO), Peter Berrett (VK3PB), and Emile Diodene (KE5QKR). Contact him at [email protected].

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If your currently on the BITX40  bandwagon of putting a kit together, or you have just  recently ordered one. You will have soon noticed the kit doesn't come supplied with a speaker, what does one expect for such a good price! But for UK builders that don't like spending their hard earned cash. I have found an abundant source of small 8 ohm speakers from the highstreet discounter Poundworld.

Two speakers including cases for One Pound!!

The speakers are marketed for use with portable stereos, MP3 players, etc. A simple test to see if they were any good, I connected them to a reliable audio source and found although not HI-FI, they are perfectly adequate for use in the BITX Kit, or other QRP constructional projects. 




They come packed in either Black or Silver.


Once unscrewed the back of the case, the speaker simply drops out to reveal a 5.5cm 2" unit.





A quick test on the multimeter revealed the value of 7.6 ohm:



Recently while out shopping I have visited 4 different Poundworld's, one as far North as Southport. All carried a plentyful supply of stock in their electrical area. I am sorry I cannot help my readers from overseas, but the unit is obviously made in China so try your Dollar shops.


Good hunting!

















Steve, G1KQH, is a regular contributor to AmateurRadio.com and writes from England. Contact him at [email protected].

If your currently on the BITX40  bandwagon of putting a kit together, or you have just  recently ordered one. You will have soon noticed the kit doesn't come supplied with a speaker, what does one expect for such a good price! But for UK builders that don't like spending their hard earned cash. I have found an abundant source of small 8 ohm speakers from the highstreet discounter Poundworld. 

Two speakers including cases for One Pound!!

The speakers are marketed for use with portable stereos, MP3 players, etc. A simple test to see if they were any good, I connected them to a reliable audio source and found although not HI-FI, they were perfectly adequate for use in the BITX Kit, or other QRP constructional projects. 




They come packed in either Black or Silver.


Once unscrewed the back of the case, the speaker simply drops out to reveal a 55cm 2" unit.





A quick test on the multimeter revealed the value of 7.6 ohm:


 
Recently while out shopping I have visited 4 different Poundworld's, one as far North as Southport. All carried a plentyful supply of stock in their electrical area. I am sorry I cannot help my readers from overseas, but the unit is obviously made in China so try your Dollar shops.


Good hunting!

















Steve, G1KQH, is a regular contributor to AmateurRadio.com and writes from England. Contact him at [email protected].

Ultimate 3S with 5-band relay module in front, variable LM2596 power supply (with voltmeter) for the power amplifier behind left, a variable LM2596 supply set for 5 Volts for the Ultimate 3S in the middle, and the antenna switch to the right in the back.

WSPR – The system for Weak Signal Propagation Reporter makes it easy to compare antennas if your transmitter can instantly switch antennas. The system shown here can send on antenna 1 for almost two minutes and then switch immediately to antenna 2 for the next transmission.

The Ultimate 3S already has software that supports that and application note 3 from QRPLabs (Controlling additional relays using the Ultimate3S “Aux”) describes how. I built mine following that note and the experience from EA1CDV.

The circuit is controlled from pin D7 and consists of a transistor, a relay, a resistor and an electrolytic capacitor. In addition I have two LEDs that indicate which antenna which is in use. In the first picture the green LED in the back right under the BNC antenna connector shows that antenna 1 is connected.

In the next picture, the whole layout is shown a little better. In this case LED 2 is lit, the faint yellow one. It sits right under the additional SMA antenna connector in the top left-hand corner that I had to fit.

I have used this setup for a few days now on 7, 10, 14, and 18 MHz with some crossed doublet antennas (somewhat like this setup, but not in the same location). I change the frequency between antennas, e.g. 50 Hz below the center frequency of the band for antenna 1 and 50 Hz above for antenna 2 in order to simplify discrimination between the transmissions.

The short 13 m antenna transmits best East-West, and the longer 26 m antenna North-South. The directivity is in general confirmed by the WSPR reports I see. Sometimes the difference can be more than 10 dB in SNR, but more often it is closer to 5 dB. But it also happens that only one of the transmissions is detected. This should make for some interesting analysis in the coming months.

The post “Comparing two antennas with WSPR” first appeared on the LA3ZA Radio & Electronics Blog.

Sverre Holm, LA3ZA, is a regular contributor to AmateurRadio.com and writes from Norway. Contact him at [email protected].

Ultimate 3S with 5-band relay module in front, variable LM2596 power supply (with voltmeter) for the power amplifier behind left, a variable LM2596 supply set for 5 Volts for the Ultimate 3S in the middle, and the antenna switch to the right in the back.

WSPR – The system for Weak Signal Propagation Reporter makes it easy to compare antennas if your transmitter can easily switch antennas. The system shown here can send on antenna 1 for almost two minutes and then switch immediately to antenna 2 for the next transmission.

The Ultimate 3S already has software that supports that and application note 3 from QRPLabs (Controlling additional relays using the Ultimate3S “Aux”) describes how. I built mine following that note and the experience from EA1CDV.

The circuit is controlled from pin D7 and consists of a transistor, a relay, a resistor and an electrolytic capacitor. In addition I have two LEDs that indicate which antenna which is in use. In the first picture the green LED in the back right under the BNC antenna connector shows that antenna 1 is connected.

In the next picture, the whole layout is shown a little better. In this case LED 2 is lit, the faint yellow one. It sits right under the additional SMA antenna connector in the top left-hand corner that I had to fit.

I have used this setup for a few days now on 7, 10, 14, and 18 MHz with some crossed doublet antennas (somewhat like this setup, but not in the same location). I change the frequency between antennas, e.g. 50 Hz below the center frequency of the band for antenna 1 and 50 Hz above for antenna 2 in order to simplify discrimination between the transmissions.

The short 13 m antenna transmits best East-West, and the longer 26 m antenna North-South. The directivity is in general confirmed by the WSPR reports I see. Sometimes the difference can be more than 10 dB in SNR, but more often it is closer to 5 dB. But it also happens that only one of the transmissions is detected. This should make for some interesting analysis in the coming months.

The post “Comparing two antennas with WSPR” first appeared on the LA3ZA Radio & Electronics Blog.

Sverre Holm, LA3ZA, is a regular contributor to AmateurRadio.com and writes from Norway. Contact him at [email protected].

Judy and I went cross-country skiing down at the Pemigewasset River near Profile Falls. I brought the KX3 and made 18 QSOs (in the CWT sprint) including France, Italy and Germany. It was a bit over 50F.

What a fantastic day to be out. We went east from the road about a half a mile toward the river. Here it opens up into a large field. At the far edge are some picnic tables and the river.

I tossed my 30 foot wire over a pine branch and pulled the wire up over the picnic table. In the sun, it must have been over 70F, because I took off my coat and gloves and I was still hot.

I started out on 20 meters. The CWT sprint had been running for a half hour. Except for the sprint, the band seemed dead. I had no trouble making contacts. After making a dozen contacts on 20 meters, I switched to 40 meters and made another six. Here’s my log. I’ve changed the format to reflect a more normal log rather than using the CWT exchange format.

22 Feb-17 1930 14.026 N5ZO CW 599 599 CA Marko
22 Feb-17 1932 14.027 K0AD CW 599 599 MN Al
22 Feb-17 1933 14.035 F6HKA CW 599 599 France Bert
22 Feb-17 1935 14.036 DL2CC CW 599 599 Germany Frank
22 Feb-17 1936 14.040 KM0O CW 599 599 MN Tony
22 Feb-17 1938 14.032 N4ZZ CW 599 599 TN Don
22 Feb-17 1940 14.030 AC4CA CW 599 599 TX John
22 Feb-17 1942 14.029 WJ9B CW 599 599 NC Will
22 Feb-17 1943 14.030 IT9MUO CW 599 599 Italy Alf
22 Feb-17 1944 14.033 N4IQ CW 599 599 SC Bill
22 Feb-17 1947 14.035 K9UIY CW 599 599 Ill Vic
22 Feb-17 1950 7030 NA8V CW 599 599 MI Greg
22 Feb-17 1951 7031 K4HQK CW 599 599 VA John
22 Feb-17 1952 7036 K3WW CW 599 599 PA Chas
22 Feb-17 1953 7037 CG3KI CW 599 599 ON Rich
22 Feb-17 1954 7039 N3RS CW 599 599 PA Sig
22 Feb-17 1956 7039 VE3KP CW 599 599 ON Ken
22 Feb-17 1957 14.035 K4BAI CW 599 599 GA John

With this I packed up and headed back to the car. It’s been a long winter with plenty of snow during the last month. What a thrill to be outdoors again with a rig.

Jim Cluett, W1PID, is a regular contributor to AmateurRadio.com and writes from New Hampshire, USA. Contact him at [email protected].