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I had a lot of good response from some bread board based projects in the past.  so, here is a neat little AM transmitter I stumbled on Instructables.

It’s simple enough that you may already have most of the spare parts, yet detailed enough to allow you a little room for modification.  I like building transmitters like these and sending audio to my old broadcast radios or even amateur receivers like my old Hallicrafters gear.

Want to really freak people out?  Build one of these and hook it up to an MP3 player or portable CD Player (not like we have a massive use for these) and use it to stream old time radio.  Tons of resources online.  it just seems right to listen to classic radio on…… a classic radio.  I have an old American Bosh console with great woodwork, classic styling and such.  Hooked it up to my MP3 player and listened to the entire broadcast day of CBS on “D Day”.  Really kewl!  The Shadow hasn’t sounded this cool in quite some time.

Here is a link to the AM transmitter in the photo:

http://www.instructables.com/id/Easy-AM-Transmitter/

Here is a slightly different approach.  Lets say you have found a great condition cabinet at a tag sale, but the parts inside are truly destroyed.  I, don’t like modifying a restorable gem.  But…….  If you want, you could take an MP3 player, load it up with your favorite shows and have a great tabletop discussion piece.  You can get MP3 players REALLy cheap even at a drug store for ten bucks or so and load quite a bit of audio.

Here is the link for the MP3 player in a classic radio project:

http://www.instructables.com/id/Vintage-Tube-Radio-Restoration-MP3-Upgrade/

Don’t think I left you guys out with some neat radios from the 70′s and such.  Especially those radios that came out around the time of the great Sci-fi flicks.  Ohhhh, I wish I had one of those vintage Welltrons!!!!!!!!

Below is a neat FM transmitter project.  I like this because it gives you a different dimension into the different modes and won’t cost a lot of money to truly learn a lot.  This title is called “How to build the simplest FM transmitter”:

http://anarchy.translocal.jp/radio/micro/howtosimplestTX.html

Tailgate action as K4UPG buys a MFJ 207

Wahoo! It is that time of year again. I am counting down the days to one of my favorite ham radio activities… Orlando Hamcation is coming on Feb 11-13.

After reading the editorial in the new issue of World Radio Online a cord was struck that resonated with this here ham. I realized that I have a common disease. The article says, “Seems there are a lot of radio amateurs suffering from IDGOTAES.” OH NO… I have it. Throughout the month of December and most all of January, I’ve been sidetracked with other priorities and without realizing it have become afflicted with IDGOTAES. ( “I Don’t Get On the Air Enough Syndrome” )  This is a bad one and only can be cured by some serious outdoor QRP activity if you are a true portable QRP op like me.

Praise the Lord, there’s some good opportunities to get on the air coming up and one cannot find a better place to stock up on goodies than the vendors, swap tables and tailgate are  of HAMCATION. So kick off the winter snow-bound blues and git on down here and enjoy with me.

Feeding frenzy at the vendor area of Hamcation!

Tailgate area is HUGE!

We’ll be holding an unofficial gathering of QRP types on Saturday Feb 12, 2011 at Hamcation. Let’s meet up at noon at the QRP ARCI booth and swap stories and get to know one another. Look for the wild eyed guy in the bright yellow cap that says K4UPG on it and his very distinctively white haired partner Jim K4AHO won’t be far away! Be there and let’s get over this dreaded disease together as we plan some Central Florida QRP Group outings for the rest of the year.  QNI? Ya hear?

72,

Kelly K4UPG PB #173

Calling all Central Florida QRP Ops… there’s a small group of us in Orlando that like to gather together on the 2nd Saturday of the month for some breakfast, show n tell, and portable ops in a nearby park.

Antenna Tweakers

Operating site

K3RLL in action with KX-1

We just had a nice time of antenna tweaking and operating down by Lake Sylvan. There’s still room for more of you, so mark your calendars and plan to join us on the 10th of December 2010. Leave me a comment if you’d like me to send an email reminder to join us, or if you’d like to get on our list for future outings. Snowbirds are welcome too!

72,

Kelly K4UPG PB #173

With W1AW practically in my back yard, I get to play with some expensive toys.  I volunteer there from time to time….. and really get to play with some toys!  One thing I’ve learned (and try to teach new hams in my classes) is….. spend more time listening than transmitting!

So, on all my non homebrewed rigs, I have spent tons of time learning how to use, or installing filters and figuring out not only how they work, but how they truly help me on the air.  Software defined radio has also shown me some really neat things that can be done just playing with bandwidth and CW (especially trying to work a DXpedition!).

To that end, I finally got to play with a few switched capacitive audio filters that really had me thinking, why do I not have one!

Today I’m going to show you a few projects that can get you going.  First, the image on the right is from the NEQRP Club and their NESCAF project.  The theory of operation, I’ll quote from their website: http://newenglandqrp.org/nescaf

The integrated circuit at the heart of the NESCaf is made up of two CMOS active filters. These filters are extremely configurable (low pass, band pass, notch etc).

We have chosen to set up both filters as Butterworth band pass filters and to cascade the filters. Butterworth filters have the characteristic of constant amplitude in the band pass region, while the cutoff knee is not be as sharp as if the filter were configured as a Chebychev. We considered this an acceptable tradeoff, wanting constant volume out regardless of the bandwidth or center frequency setting of the filter.

There are two on-board trimmer pots. One is used to “calibrate” the center frequency pot. This allows you to adjust the frequency at which the center detent occurs. If you are using a rig with a transmit offset and sidetone of say, 700 Hz, you can use this trimmer to make that the center-detent frequency. The other on-board trimmer adjusts the audio level into the filters output amp. Using this pot, you can set the overall gain of the filter. This can be used to set the filter for unity gain, if desired. This way, the filter could be switched in and out, and still maintain a comparable volume level in the headphones.

Pretty neat!  This is a relatively simple kit that the club has been offering for quite awhile.  Out of stock now, but will be available again soon and priced really inexpensively – under $35.00.  If you want, all the information is available int he schematic and documentation if you want to “roll your own”.

There are some commercial offerings as well, many we have seen advertised like the one from Idiom Press (http://www.idiompress.com/scaf-1.html).  This one works VERY well, and comes as a complete kit with an enclosure.  There is some good information on the Idiom Press site that shows the response curve as well as why the filter doesn’t use DSP.  This kit is a bit more, but has an extremely high quality/professional looking enclosure and sells for $89.95.  I can’t afford one now, but when I can, I plan to build one and post details here with audio files (there is an audio file that can be played on their website to demonstrate the audio characteristics).

Here is a great video of NG9D’s build of the SCAF-1:

But, I don’t want to make this just a CW project…… how about AM?

Stewart (“Stu”) Personick, AB2EZ is a ham that wanted to work a bit on his transmitted and received audio.  He took the SCAF-1 and modified it in true ham spirit.  From his online writeup of the project:

My original objective was to demonstrate, to the AM community, the use of a switched capacitor filter for “brick-wall” bandlimiting of the output of an AM audio chain… in order to limit the bandwidth of the r.f. output signal produced by a vintage high-level-modulated vacuum tube transmitter, or a modern FET-based “Class E” transmitter.

What’s really neat, is this is a relatively easy mod to build in and expand the already excellent capabilities of a great kit/filter!  You can find full details of this modification at:  http://mysite.verizon.net/sdp2/id14.html I think the Idiom Press site has copied this info on their site as well.

A little more research on the topic led me to “An Adjustable Audio Filter System for the Receiver” by Lloyd Butler VK5BR (Originally Published in Amateur Radio, March 1995).

This is also a “roll your own” project, but gives some detail on the use of the filter in CW, RTTY, voice and other narrow bands.  This article was originally published 15 years ago and is still VERY relevant today.

I took a look at the schematic and it’s not entirely too difficult to build this in an evening or two and looks like a very useful and educational shack accessory.

You can find the article and schematic at: http://www.qsl.net/vk5br/SwCapFilter.htm

Hopefully this will whet your appetite and make you want to fire up your soldering iron and build a useful filter for your operating needs.  I know after using a few of these filters I’m left to wonder, “how did I NOT learn about switched capacitive audio filters!”.

Recently I began a project for a wire vertical antenna and it called for a 20 ft fiberglass or non-conducting pole/mast of some sort. Not to worry as I have a trusty 20 ft Jackite pole in a nice green color. I put the antenna together but the vertical wire was too long and so there was considerable slack wire swinging in the breeze. After some head scratching, I measured my 20 ft Jackite and found it was only 18 ft long!!! YIKES! Did it shrink?

Did it shrink? Nope, it is all good to go!

Thanks to the internet, I was able to send an email to Jackite products and ask if that was normal. In a short time, I received a very nice response from the Jackite vp and an offer that was over the top and way more than I was expecting. It was more than I could accept as I’ve been quite happy with the product otherwise. Turns out that it was a small quality control issue that I can tweak and correct personally.

I get no monetary or other gain out of this, but did want to give credit where credit is due. This level of customer support is often lacking in today’s busy world. I am glad to give a shout out to this company and its products! They do the job and the company stands behind them with good service. Outstanding job Jackite!

72,

Kelly K4UPG PB #173

For readers local to my home area you may be interested in this exciting and free event in Ottawa this weekend. Full details can be found on the Artengine website. The essential details are:

Dates and times: Nov. 6th and Nov 7th, 12pm to 6pm.

Location: Arts Court 2 Daly Ave. Ottawa, ON K1N 6E2

If you are not sure what makers do or what goes on at a Maker Faire take a look at this video of the 2010 Kansas City Mini Maker Faire

Yep, it is confirmed now for sure. Compulsive Antenna Disorder has haunted me since I was first licensed and ran a coax fed 80 meter dipole on multiple bands without a tuner.  The first time the symptoms were noticed by my family and friends was when I got a couple OO tickets for out of band harmonics. Hmmmm… what’s up with that? So a bit of reading and the antenna tweaking began and that’s when it all started.

Soon thereafter I tried to load up a nifty pin from my Junior Prom Boutonnière that reminded me of a triple stacked halo for 1296 Mc (MHz for the newer ones amongst us).  Then it was the handheld yagis for 432 Mc that we used with some military surplus gear that used dynamos so we could chase tornadoes. (We thought if it bounced off the moon, it should bounce off of a tornado!) The saucer sled that became a parabolic for listening to satellite telemetry and on it goes… Compulsive Antenna Disorder has had a firm grip on me for some time now.

Am I dreaming? Thanks wiki images!

As a QRP operator, I am always looking for more antenna power. I know that somewhere out there simply MUST be a silver bullet, that magic QRM and pileup busting antenna that makes my 2 watts output sound like a full gallon.

I can say one thing for sure, I know a lot of non-silver bullet antennas, as I have a box full of them.

But they still make a few QSO’s at times and I’m having fun along with a bit of frustration and disappointment as I deal with my CAD affliction.

I’m told that much like telegraph key collectivitis there is no known cure or relief. I share in your grief brothers and sisters…

72,

Kelly K4UPG PB #173