Aluminum Foil 20 Cm Antenna For 10 M Operation

July 2, 2022 by Chris Lott 11 Comments

[David], DL1DN, is an Amateur Radio enthusiast with a penchant for low-power (QRP) portable operations. Recently he was out and about, and found that 10 m propagation was wide open. Not discouraged by having forgotten his antenna, he kludges up a makeshift one using a 20 cm length of aluminum foil (see video demonstration below the break). [David] wasn’t completely unprepared, as he did have the loading coil for his portable 20 m antenna, but was missing the telescoping whip. He calculated the whip length should be around 20 cm for 10 m operation, and crinkles up a sheet of foil the approximate length. He tunes it to length by rolling the tip to shorten the “whip” until he gets an SWR minimum.

Schematic of [David]’s QRP Portable Whip Antenna

[David] describes this style of portable antenna in another video, using a more conventional telescoping whip as the radiating element. The loading coil is built from common PVC pipe and insulated wire. While these aren’t necessarily the most efficient antennas, they can do the trick when portability is a major concern. For a different approach, here’s a QRP Hackaday.io portable antenna project using a magnetic loop antenna. But for the ultimate in QRP, check out this transmitter we wrote about in 2013 that uses only voice power to operate.

What are some unusual items you’ve used as makeshift antennas? Let us know in the comments below. Thanks to [mister35mm] for submitting this to our tip line.

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PSSST! Here’s A Novel SSB Radio Design With Only Seven Transistors

November 20, 2021 by Ryan Flowers 41 Comments

When [Pete Juliano] sat down to design a sideband transceiver for the 20 Meter (14 MHz) ham radio band, he eschewed the popular circuits that make up so many designs. He forged ahead, building a novel design that he calls Pete’s Simple Seven SSB Transceiver, or PSSST for short.

What makes the PSSST so simple is not only its construction, but the low component count. The same circuit using four 2N2222A’s is used on both transmit and receive. On transmit, an extra three components step in to amplify the microphone input and build output power, which is 2.5-4 Watts, depending on the final output transistor used. The best part is that all of the transistors can be had for under $10 USD! [Pete] shows where radio components such as the RF mixers and the crystal filter can be purchased, saving a new constructor a lot of headaches. The VFO and IF frequencies are both provided by the venerable si5351a with an Arduino at the helm.

Many simple transceivers are designed to demonstrate a minimum viable radio, with performance not really a goal. On the other hand, the PSSST was modeled stage-by-stage in LTSpice, ensuring great transmit audio and nice receiver performance. Be sure to check out the demonstration below the break!

[Pete] has painstakingly documented the entire project on his website, and the code for the VFO is available by request via email. We appreciate this contribution to the homebrew ham radio community, and we’re sure this will provide many nights of solder smoking enjoyment for radio amateurs around the world.

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Amateur Radio Transmits 1000 Miles On Voice Power

November 26, 2013 by Adam Fabio 50 Comments

Many of us tried the old “Two tin cans connected by a string” experiment as kids. [Michael Rainey, AA1TJ] never quite forgot it. Back in 2009, he built “El Silbo”, a ham radio transmitter powered entirely by his voice. El Silbo is a Double Side Band (DSB) transmitter for 75 meters. While voice is used to excite the transmitter, it doesn’t actually transmit voice. El Silbo is a CW affair, so you should bone up on your Morse Code a bit before building one. Like many QRP transmitters El Silbo’s circuit is rather simple. A junk box loudspeaker is installed at the bottom of the can to convert voice power to electrical power. The signal is passed through a step up transformer, and used to excite a 75m crystal. Two NPN transistors (in this case MPS6521) pass the signal on through a second transformer. The signal is then routed through an LC network to the antenna.

Back in 2009, [Michael] brought El Silbo to the Maine coast in an attempt to make a transatlantic contact. This isn’t as far-fetched as it sounds – [Michael] has “crossed the pond” on less power. While the attempt wasn’t successful, [Michael] has made connections as far as 1486km, or 923 miles. That’s quite a distance for simply yelling into a tin can! One of [Michael’s] favorite El Silbo stories is a 109KM conversation (QSO) he had with W1PID. [Michael] found that the signal was so good, he didn’t have to yell at all. He reduced power by dropping to his normal speaking voice for the “dits and dahs”. The two were able to converse for 17 minutes with [Michael] only using his speaking voice for power. We think this is an amazing achievement, and once more proof that you don’t need a multi-thousand dollar shack to make contacts as a ham.

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