I think the QST article being referred to in this thread is one that I
remember rather clearly. I kept the issue for a long time but it got away
from me somewhere along the line. It was a lightening direction finder
using a display much like a radar PPI. It used two crossed untuned loops
and a vertical. All three signals were amplified using tubes and one of the
loops was fed to the horizontal deflection plates of a CRT and the other
loop's signal was fed to the vertical plates. The signal from the vertical
was fed to the control grid of the CRT. The project was essentially an XY
scope built from the ground up. He suggested figuring out the polarity of
things by waiting for close lightening that was visible and correlating
sightings with the display on the CRT. You wouldn't use a general purpose
scope because the fair weather condition would burn a spot in the center of
the screen. One more thing. He wound the loops in hula hoops he had cut
open. I still have two hula hoops awaiting the project. The bandwidth of
his amplifiers was low audio to about 100 kHz. I suspect that in today's
radio environment some tuned traps would be necessary to notch out some of
the strong signals in that frequency range. You now have all the
information I have and I am sure I could build one if only I could find the
time.
Regards.
Max. K 4 O DS.
Email: m...@maxsmusicplace.com
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----- Original Message -----
From: "paul swed" <paulsw...@gmail.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts@febo.com>
Sent: Friday, June 27, 2014 8:10 AM
Subject: Re: [time-nuts] Loran, GPS, Lightning, Timing
I have never seen an article using exotic special tubes. I understand that
benefit but common tubes do a fine job. I still believe it was a QST
article. Maybe 73 magazine. It was a long time ago. When I started using
the 12AU7s again for the vlf pre-amp they were $1 or so 7 years ago. Now
audiophiles have driven them into the silly range especially on the
websites. I scrounged 4 at really good prices $2 recently. But the
audiophiles were on the hunt as I noticed.
Bottom line a tube frontend is easy to build for this application. Even if
we want to make it seem hard. Its simply not the front end. Its the other
parts of the solution that should be the focus. How to make a sub $$
solution. The European solution is several hundred Euros. $$$$
Regards
Paul
WB8TSL
On Thu, Jun 26, 2014 at 10:50 PM, Brian Lloyd <br...@lloyd.com> wrote:
On Thu, Jun 26, 2014 at 9:08 PM, DaveH <i...@blackmountainforge.com>
wrote:
> The tube was probably the FP-54
>
> http://frank.pocnet.net/sheets/141/f/FP54.pdf
>
> No luck on finding the article - it is not in the Handbook of Projects
for
> the Amateur Scientist by C.L. Stong
>
>
>
http://www.sciencemadness.org/library/books/projects_for_the_amateur_scienti
> st.pdf
>
> I thought it might be as I remember there was a project to detect
> sferics
> but this one used plain 12AU7s and 6AU6s
>
When I was a kid this may have been my favorite book. I did build the MRS
when I was 12. Sucker actually worked too! I was amazed. I have built
several things from this and used many of the projects with modern
electronics as projects for my students in middle school.
--
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
br...@lloyd.com
+1.916.877.5067
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