FB QRP Homebrew From India

I always liked the descriptions of the ingenious homebrew stations used by Indian radio amateurs. This morning I came across VU2LID's site and found this:

A typical Indian QRP station will use a modified AM broadcast (BC) receiver, for the receiving part. The transmitter will usually have a final RF power amplifier using BD139 (or some power MOSFET like IRF530), driven by a Variable Frequency Oscillator (VFO) and chain of buffer/driver amplifiers (2-3 stage). Most of the stations use Amplitude Modulation (AM). Commonly available medium power Hi-Fi audio amplifier modiles using integrated circuits (like the TBA810), driving a modulation transformer forms the AM modulator part.


The above drawing was done by OM Bhasi, VU2UCY (SK)

From Sicily: An SSB Transceiver using only 5 tubes!

It's 5:30 am. I'm in the shack with a cup of coffee. The only sounds are birdsongs from the window and an Italian 80 meter SSB QSO from my Drake 2-B. Life is good.

And it got better when I found the rig pictured above. It is the work of Andrea IW9HJV and Johnny IW9ARO, two obvious victims of "The Knack" from Sicily.

It is a beautiful 20 meter SSB transceiver. And it uses just 5 tubes. While it doesn't have the bi-directionality of the BITX-20 (you can't really do that with tubes) it does share the BITX-20's simplicity and elegance of design.

The web site of Andrea and Johnny is another work of art. Check it out!
http://www.webalice.it/hotwater/RTX5x20.htm
Bravo Andrea! Bravo Johnny! Bravissimo!

Calibrating my W7ZOI/W7PUA Power Meter

In the course of testing my 20 meter DSB rig, I discovered that the chart I prepared for my

W7ZOI / W7PUA power meter had some problems. In my first effort to get some calibration points, I used a simple diode and cap peak reading signal probe to measure voltage across 50 ohms, but I may have neglected to convert from peak to RMS before calculating the power. That would certainly mess up the chart!

This morning I used my old Heathkit SG-8 signal generator and my HAMEG (20 Mhz) 'scope to get a couple of points for my graph of the response curve (line) for my meter.

I drew the new line, then used my trusty HW-8 at 1 watt to see if my chart was accurate. It was right on the money!

I look forward to happily measuring milliwatts with this very FB piece of test gear. See the June 2001 issue of QST for more details. Thanks to Wes and Bob for the great project. And thanks to Thomas in Norway for sending me the AD8307 chip.

Farhan on Schematic Drawing Software

I'm really in the dark ages on this subject -- I usually just draw something by hand and then scan it. Others (like JF1OZL) have good results with this technique. I don't. So I was glad to see this suggestion from Farhan on software that can be used to draw professional-looking schematics:

"i have used something called schemat.zip available freely on the
internet. it consists of a bitmap file with all the symbols that we
use in ham radio. i open it in ms paint, start a new copy of ms paint
and start selecting the symbols from the first ms paint window and
pasting it into the fresh ms paint window. Remember to UNSELECT
OPTIONS->DRAW OPAQUE. Sorry for the caps, but it is important. You can
use the line tool to draw the 'wires' connecting individual
components. holding the shift key down while drawing lines forces the
lines to come out perfectly horizontal or vertical."

Thanks Farhan!

SolderSmoke 83 -- Special Report from OZARKCON

SolderSmoke Podcast 83 has been uploaded. Topics covered:

Shortwave listening from the island of Ischia.
Chicago's old "Surplus Row."
New antenna yields trans-Atlantic DX!
SPRAT's minimalist MPF-102 rig.
SDR vs. HDR.
Dan's Small Parts.
LB Cebik SK.
AA1TJ's Zener Diode rigs discussed on Radio Havana Cuba.
Beacon project.
Design first, build later!
SPECIAL REPORT FROM OZARKCON!
MAILBAG: Scopes and distortion, Spectrum Analysers, new kits, 30K lemons, FDIM


You can find this episode of SolderSmoke, and all previous episodes at:
http://www.soldersmoke.com

73 from Rome

Amazing Brazilian Homebrew.. with DSB Maritaca

Every once in a while I do a Google search on "QRP DSB." This morning the search yielded a real gem: Miguel PY2OHH has a site that reminds me of JF1OZL's legendary HB pages.

There are many projects on Miguel's site, but it looks to me as if the most well-known and widely reproduced is his "Maritaca" 40 meter DSB transceiver. Miguel's page has photos of versions of his rig built by other Brazilian hams, and YouTube carries videos of several of these projects.

Miguel has been kind enough to translate into English the descriptions of many of his projects, but even on those that are not yet translated, we can all see what he has done through the universal language of the schematic diagram.

Check it out: http://py2ohh.w2c.com.br/ FB Miguel! Muito obrigado!

Dan's Small Parts Temporarily Closed

Dan's web site reports that there was a bad accident, and that his business is temporarily closed, but that "Dan will be back." Let's all wish Dan the best of luck. Many of us depend on him to keep our junk boxes well-stocked. I was just getting ready to send him an order.

80 in the morning, LTSpice, QRP Blog

I am an early riser -- I am in the shack with coffee cup in hand each day by 0515. At sunspot minimum, that's just not the best time to be on the air. But 80 meters has come to my rescue. I've discovered that I'm not the only ham in Europe who gets up early. The CW guys are there first; phone ops seem to sleep in a bit. With my HW-8 and end-fed wire, I work a few stations each morning. (Today I worked TK7C on Corsica. ) Later on I listen to some AM enthusiasts who meet on 3705 kHz. And there is some great Italian tech talk (mostly about old tube rigs) on 3643 kHz. I plan on building an 80 meter DSB transceiver. (I've joked with Michael, AA1TJ, that on this project I plan to design first that THEN build.)

I've the LTSpice Yahoo Group for some guidance on how to model bifilar and trifilar toroidal transformers in LTSpice. I'm not sure I'm doing this right.

Found a great QRP Blog this morning: http://www.theqrper.blogspot.com/

Alan Yates: Electronics Wizard!

I first met up with Alan in 2002 when I spotted his web site describing a "Trivial Electric Motor."
My son Billy and I built one and sent Alan a report.

Alan clearly has "The Knack." Check out his site: http://www.vk2zay.net/category.php/13

Items recently mentioned on SolderSmoke

Here's Nick WA5BDU's FB site. I really liked his discussion of the design and construction of his 60 meter SSB transmitter: http://kennnick.googlepages.com/home

Here's Stan 9H1LO's 10 meter beacon page:
http://www.9h1lo.net/beacon.php

Here is the "Homebrew QRP is Good 4 U" site of KC6WDK
http://www.qsl.net/wb5ude/kc6wdk/index.html

Here's the transatlantic balloon project: http://www.spiritofknoxville.com/