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HAM SIGNAL

Thoughts,observations,experiments, and ramblings in Amateur Radio by N1DAY and KC4SIT.

LIGHTBULB QSO PARTY - CLICK HERE

The 50' coax rule has been eliminated. Click above button for updated rules.

Updated Lightbulb Antenna Schematic

09/08/2018

I recently drew thus updated schematic to show changes made after switching over to the Satco S2431 lightbulb. This schematic shows the roller inductor and associated housing that allows easier tuning on the 20M band. Looks a bit like an RPG, doesn't it?
Bulb Size Matters

09/02/2018

Finally I took delivery on a Satco S2431supersized bulb. The bulb is over 12" long and has what I estimate to be about a 72" filament inside. The first two that were shipped to me did not make the trip through the postal service system and arrived with broken stems. The bulb reminds me of a partially inflated football. Satco S2431 installed and ready for work As expected, the new bulb required new tuning taps on the antenna loading coil due to the added length of the filament which
Modeling the Light Bulb Antenna

08/29/2018

I was thinking about modeling of the light bulb antenna today and lamenting the lack of a bulb selection feature in the various NEC applications. However, using a short wire as a replacement for the bulb confirmed recent findings from field strength measurements with and without the bulb inserted into the antenna. See here for details: https://hamsignal.com/blog/yet-more-lightbulb-antenna-experiments To explain how I think the lightbulb antenna is working, let's start off by reviewing
Yet more lightbulb antenna experiments

08/26/2018

I have to admit, this whole lightbulb antenna thing has me continuing to scramble for why it works like it does. Today, I spent the better part of the day with my field strength meter taking a bunch of measurements at various distances with and without the bulb installed in an attempt to better understand this antenna. What I discovered was something pretty interesting that seems to be more pronounced on 40M than on 30M and 20M. From the tap point on the coil up to the top of the coil, and
More tests on the lightbulb antenna and impact of the bulb on propagation

08/25/2018

I continue to receive emails asking about what is causing the whole lightbulb antenna thing to work. Some hams commenting on the antenna are adamant that I am contacting other stations at distance due to the radials, coax and coils and not because of the lightbulb. As I too was quite surprised to be making distant contacts on such a small antenna, more research was in order. In addition to conducting the radiation tests on various parts of the antenna with my field strength meter, which can
Light Bulb Propagation Performance

08/23/2018

It has been several days now since I started transmitting with my lightbulb antenna. This morning I made a map of where I have been making FT8 contacts. I find it interesting that the antenna seems to be performing a bit better on 30M and 40M when I thought 20M would be the band that would really shine. The map does not show contacts made to Cuba and Germany. I think the map will evolve over time because at this point, there is a bias toward more local stations as that is where I have been
First Transatlantic and Bulb to Bulb Contact on FT8.

08/21/2018

August 19- 20, 2018 were historical days here at Upward Signal Research atop the Eastern Continental Divide as KC4SIT and N1DAY continue their research into lightbulb antennas. On August 19, we completed our first Bulb to Bulb QSO using FT8. The distance between stations was a mere 8 miles, but that is OK for now as there are not too many bulb operators out there. First Bulb to Bulb FT-8 QSO KC4SIT was using the original prototype bulb antenna #1 and N1DAY was using the second
Dummy Load or Antenna?

08/19/2018

Now this is a good question. Historically, the lightbulb has been well documented in its use as a dummy load. However, every article I read on the lightbulb dummy load makes mention of contacting someone several to a hundred or so miles away while transmitting into it. For me, that strongly suggests that at least some of the RF that is going into a lightbulb doesn't get converted to heat or light as some RF has to be emitted from the lightbulb in order for the qso to occur. Right? In my
New and Improved Lightbulb Antenna

08/18/2018

Work continues at a brisk pace here at N1DAY to build a better lightbulb antenna. As some readers know, I am now committed to having the LightBulb QSO Party. You can read about it by clicking on this URL: https://hamsignal.com/blog/the-lightbulb-qso-party and get some FAQs on the original light bulb experiments by clicking on this URL: https://hamsignal.com/blog/light-bulb-antenna-basics-and-faq I advise everyone to consider the new design detailed below as it is a much better performer