10m band loop

A magnetic loop can be a very effective HF antenna, especially when the very sharp tuning is not an issue. They can be very efficient but there is a trade between bandwidth and efficiency. They are ideal for modes that do not need frequent retuning such as PSK31, JT65 or WSPR. Ideally the inductor should be made of copper pipe or thick coax and the capacitors need to be low loss and high voltage types. Tuning is usually very sharp. Having said all this. quite decent results have been obtained with loops made of quite thin wire.

See https://sites.google.com/site/g3xbmqrp3/antennas/magloop .

A very successful antenna for VLF, LF and MF receive only is an E-field probe. Ideally these should be mounted outside the house with some experiments to find the quietest spot. Size is not important and these are much smaller than many antennas for much higher frequencies.  The picture shows an example EFP. This is the complete antenna – no wires or loops etc are needed in addition. They can be made by just about anyone, so there is nothing stopping you having fun on 136,472 or even VLF RX.   Some people have built these inside a short length of uPVC pipe. The important thing is they are very small and work well on the lower bands.

I have also used EFPs as mag mounts on the car when looking for my signal on 136kHz QRSS3. These are very compact antennas. PA0RDT has created a good design that many people are using.

See https://sites.google.com/site/g3xbmqrp3/antennas/efp .

I see Elecraft has launched a deluxe version of its K3 transceiver. The K3 was already a pretty good rig and the S version will be even better, but sadly far too expensive. I guess Elecraft is right that this will be many times less expensive than similarly spec’d transceivers, but to me this is still far too much for an amateur radio rig. Don’t forget that lots of the features cost more – like the mic and 2m!

At half the price maybe, but certainly out of the question here in the UK when shipping, import duty and VAT have to be added. I am able to get lots of fun from our hobby spending just a small fraction of the cost. There will always be people who will pay these prices and buy a tower and a big beam.  Sorry, but this is not for me. I wish Elecraft well but feel they will need to slash prices soon to compete with the Chinese. An alternative is for Elecraft kits to be shipped from China. Sorry, but this may be the only way they will be able to compete in the future.

My 99-cent Amazon Dash Button arrived today and I was excited to get a look at it. The little device feels very sturdy. Unfortunately, my wife told me she had no interest in ordering laundry detergent by pressing a button, so I had to figure out what to do with it.

I decided to open it up and do a teardown. For science, of course.

The FCC ID is 2ACBE-0610. Documents in the FCC filing appears to confirm that this is indeed an 802.11b/g/n device (not Bluetooth, as initially thought).

It has a large white button with a red/green LED.

FCC ID: 2ACBE-610 / Model JK76PL

Removing the back of the case reveals a Li-ion AAA battery

Can anyone identify the wireless radio chip?
Other interesting components?

Whether or not you find it useful to order your laundry detergent at the touch of a button, this has to be one of the least expensive 802.11 devices ever produced.

I wonder what the actual component costs are? I think it’s safe to say more than the 99 cents that I paid for it.

Update 5/12/15:

It looks like Matthew Witheiler @ Bit of Cents has figured it out:

At the heart of the Dash is a USI (Avnet) 850101. The 850101 is a combination wireless module (Broadcom BCM43362) and micro controller (ST Microelectronics STM32F205). This makes the Dash capable of connecting to 802.11 b/g/n networks with its 120MHz ARM Cortex-M3 processor. It also happens to be exactly the same chip used inside the $19 Spark Photon.

A couple of friends and I did a trip to Kearsarge Mountain today. We had a fantastic time and made a couple of dozen nice contacts. Dave K1SWL, Tim W3ATB and I met at Kearsarge. The view was fantastic.

Dave brought his KX3 and put up a simple vertical wire 28 feet long. He sat at a picnic table directly under the wire and had a short counterpoise. The internal tuner managed the setup just fine. Dave made a dozen DX contacts mostly on 15 meters. I don’t have his log.

Tim brought his HB-1B and wanted to test out a 30 meter dipole he made. He plans to use it during an upcoming trip to Antigua. The antenna had a great SWR. After the test he switched to 20 meters and used his Par End Fed as a horizontal up about 25 feet. He made three stateside QSOs and was thrilled with the results.

I set up with a west facing view. I placed an inverted L up about 25 feet and across about 40 feet. I tuned the wire with the internal tuner on the KX3. I was hoping to make some SSB contacts in the military cross-band exercise and I had a mic out for awhile. But I abandoned that effort and went back to CW. Here’s my log:

9 May-15 1555 24.891 US5WE CW 599 599
9 May-15 1558 21.012 EA2NN CW 599 599
9 May-15 1600 21.026 SN7Q CW 599 599
9 May-15 1652 14.021 K3ZO CW 599 599
9 May-15 1655 18.087 AO150A CW 599 599
9 May-15 1657 21.021 HA3NU CW 599 599
9 May-15 1700 21.016 M0BEW CW 599 599
9 May-15 1701 24.891 US5WE CW 599 599
9 May-15 1705 18.082 R120K CW 599 599
9 May-15 1706 18.087 AO150A CW 599 599

I wasn’t paying attention and realized back home that I had several dupes.

We operated about an hour and a half and had a nice picnic lunch before heading down the mountain. Working DX was a lot easier today than battling the black flies. They were pretty thick and we were all glad to have a nice breeze and some bug spray handy. The little park area midway up the mountain makes a perfect place for operating on a beautiful day.