Category Archives: NE1RD

Small Wonder Labs Retro-75 Kit Arrives and Project Start

The Retro-75 Board Kit has arrived this week. It came in two parts, everything but one component which arrived separately a few days latter (there was a note in the first package).

I’ve a satellite antenna project with my son Victor KC9NWB and a frequency reference for my shack to finish, both “on the bench” to complete first, putting the Retro-75 into a May build.

That will give me time to layout & source an enclosure, the second crystal socket & switch I will install and have those items on hand for the build.

My initial post on the Retro-75 is at: Going Retro on 75m AM – Small Wonder Labs Kit

I’m planning to shoot pictures and write something about all three projects as they go along.

73

Steve
K9ZW

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Diana Eng KC2UHB reports from Mass QRP Convention

Diana Eng KC2UHB does a short video report on Masscon – the QRP Convention spearheaded by Scot NE1RD

More at Make Magazine’s Blog: http://blog.makezine.com/archive/2010/03/massachusetts_qrp_convention.html

(You may remember Diana KC2UHB from A Visual Demo of How a Yagi Antenna Works – MAKE Magazine )

Masscon has posted a whole bunch of post-event items at: http://www.masscon.org/

73

Steve
K9ZW

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Going Retro on 75m AM – Small Wonder Labs Kit

Small Wonder Labs Retro-75 AM Transceiver

Small Wonder Labs Retro-75 AM Transceiver

Based on write-ups and recommendations from Scott NE1RD and Jeff KE9V, I took at look at Dave K1SWL’s newest offering “The ‘Retro-75’ 75/80 Meter AM Transceiver board kit.”

Although AM has long been supplanted by more effective modes of communication, AM activity is largely channelized into ‘watering hole’ frequencies2. It’s therefore pretty easy to find activity on the air. Here in the Northeast, 3885 kHz is the ‘hot spot’, and 3880 kHz is similarly used on the West coast.

Receiver:

The receiver front end is entirely conventional. …. Rather than wrestle with more stages of filtering or the use of ceramic filters, I reverted to a tried-and-true crystal filter. ……

The IF amplifier uses the so-called ‘cascode’ configuration…..

The following stage is a peak detector which serves to recover the modulation envelope from the received signal. Q3 is an ‘infinite-impedance detector’- a JFET biased near cutoff. I’d always wanted to say I’d used one- the phrase has a nice ‘Hitchhiker’s Guide’ ring to it…..

….

The audio output waveform is also peak-detected … and applied back …. as a form of Automatic Gain Control (AGC). Without it, nearby ‘Big Gun’ stations are easily capable of saturating this amplifier stage, yielding harsh-sounding clipped audio. …. With this feedback path in place, even the strongest of stations sounds fairly clean in the receiver.

Transmitter:

The RF strip consists of a crystal-controlled Colpitts oscillator, a FET-driver IC, and a MOSFET Power Amplifier stage. The PA stage runs class-C to keep the transmitter efficiency reasonably high. Generating an amplitude-modulated output is done using one of the oldest tricks in the book: the transmitter’s supply voltage is varied by superimposing audio on it through … an inexpensive 48Ω:3.2Ω audio output transformer. ….

In theory, this method is simplicity itself….. The transmitter runs about 2W of carrier power and 6-7W peak output. I ran key-down tests of up to a half-hour duration- they showed minimal transformer warming.

….

Receiver ‘Test’ function:

One of the impediments to building an L-C oscillator (here used as the receiver LO) is that component tolerances make the resulting operating frequency somewhat uncertain. CW/SSB projects can usually count on a borrowed signal from a ‘big rig’ in the shack to locate and adjust the local oscillator to frequency. With AM, though, there’s no ‘beat note’, and you’ll probably hear an ‘in-shack’ AM signal everywhere you tune. The circuit block labeled ‘Test’ provides a built-in frequency adjustment tool. …. (Quotes taken from Dave K1SWL’s Kit Instructions)

The Small Wonder Labs Retro-75 AM Transceiver Board Kit is so new it isn’t even linked from Small Wonder Labs Homepage and can be found at Small Wonder Labs Retro-75 AM Transceiver Web Page

It is listed in the ordering section of the main Small Wonders Lab Website.

I received a nice note from Dave K1SWL thanking me for my order. And I have to admit I am enthused to see it arrive; even more to do the build & get it on the air!

73

Steve
K9ZW

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CaribbeanBUDDIES 2010 – Activate St Lucia Island (J6) from Feb. 2-10

Our Friend Scott NE1RD provided a copy of the group DXpedition’s Press Release for CaribbeanBuddies 2010. Scott NE1RD again is a DXpedition member, and I hope to work him while he on-island this trip!

http://dx-hamspirit.com/2009/11/caribbean-buddies-dxpeditions/
http://sites.google.com/site/caribbeanbuddies/home
http://caribbeanbuddies.blogspot.com/

Caribbean Buddies off to St Lucia (J6) for 2010


Members of the Caribbean Buddies 2010 team will mount a DXpedition to St. Lucia (J6) February 2-10, 2010. Nine operators from eight states will have fixed operations from a cliff-top villa and portable operations from various points on the island using CW, SSB, and digital modes. The team consists of the following operators: Chris Drummond (W6HFP), Budd Drummond (W3FF), B. Scott Andersen (NE1RD), Dan Gagnon (WZ1P), Steve Galchutt (WG0AT), Mike Greenwood (KC4VG), Guy Hamblen (N7UN), Paul Van Dyke (KB9AVO), and Weymouth Walker (K8EAB). Licensing is not yet complete but each operator is expected to receive their owncall sign. QSL via LoTW, eQSL, or mail to operator’s home call (SASE required). See the DXpedition daily “journal” blog at http://caribbeanbuddies.blogspot.com/ or the 2010 Dxpedition website at http://sites.google.com/site/caribbeanbuddies/ for new announcements.

73

Steve
K9ZW

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After Contest University at Dayton Hamvention

An exceptionally good day at Contest University. Much more on CU when the hotel internet comes back on! Had a great chat with Scott NE1RD and he was kind enough to give me a copy of his Rockmite building book. Again more when I get to a keyboard. Raining very hard here in Dayton and hoping by morning it stops.
73

Steve
K9ZW