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Messages - tline

1
My EFHW 40 meter picks up 80 meter pretty decent, however it definitely is not resonant there.  Thinking swr more a factor for tx than rx.
2
Antennas / Re: Antenna Camouflage
January 05, 2020, 11:10:34 pm
My mistake.
EFHW-4010 63 feet, not 36.

My NanoNVA shows it resonant sweet spots at 40, 20, 15, and U.S. CB range. 
Would like to try it at 10 meters on a local net, but it's SWR starts going up again above the CB range. With a 100 watt rig, it would probably work okay locally.

One of the local 10 meter net guys lives in the house the Doren Brothers lived in. They made radios before WWI, then again in the 1920's. He's got an iron antenna tower built in like 1916 in the back yard.

http://w8ajt.hamarc.net/index.php/hamarc-hamilton-history.html
http://w8ajt.hamarc.net/images/PDF-files/doronbrosradiostation.pdf
http://w8ajt.hamarc.net/images/PDF-files/radiophotosection1.pdf
http://w8ajt.hamarc.net/images/PDF-files/radiophotosection2.pdf


I want to visit the Voice of America Museum which pretty close next to the old WLW transmitter.
They had some crazy big antenna arrays.  People could pick up broadcasts in their gutters, plumbing, and bedsprings.  WLW ran like 500,000 watts out there during the war.  in the 1980's they said the VOA arrays could stall a car engine but who knows.  They fired up the equipment on New Years eve 1999/2000 (it was water cooled with a pond and fountain in the yard) and then turned it off just for fun.  Guy in town helped build the big WLW AM tower out there. After they built it, they had to chop 8 feet off the top so the signal wouldn't overshoot Cleveland. 
http://www.voamuseum.org/the-museum/what-to-see/

i digress...




 
3
CB / Re: Is it wise to buy a CB
January 02, 2020, 04:31:18 pm

I hooked my cb up to an end fed 40 and was happily surprised when it seemed to work pretty good.


Quote from: gil on December 26, 2019, 09:05:46 amIt certainly isn't what it used to be... A half-wave end-fed wire with a 49:1 transformer would be the best antenna for CB IMHO. Height is your friend for local comms...
Gil.
4
Antennas / Antenna Camouflage
December 27, 2019, 12:13:42 pm
Was thinking about using a Spiderbeam mast in an urban environment.  Little white houses, small yards, big old trees.  Was wondering if a Spiderbeam mast could take a coat of paint, and still be able to extend and fold back together okay.  And what colors of paint, glossy or flat etc, would make it less visible among the little white houses, grey roofs, big green trees, and a blue or grey sky.

Any ideas on using a 36 ft end fed half wave on this type of structure would be appreciated as well.  Am trying from the side to a back tree and back to the house in a funky horizontal V shape now.  Hesistant to lay it directly on the roof to get more height, but concerned the swr would suffer.  Experimentation has been slow due to weather, dragging a ladder about, and the roof it not safe to walk up, although I can reach the peaks with a ladder. 

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5
CB / Re: Is it wise to buy a CB
December 22, 2019, 07:38:59 pm
Got my CB for 10$ at a yard sale. Only way it felt worth it. Had to fix a cold solder crack and it works fine.
A few truckers still use them but I avoid the interstate and the few locals who use it are in their own world but not offensive.
The "SUPERBOWL" is on channel 6 (US) and is interesting urban guys using illegal power chattering non stop without anyone else talking to them.
Not the friendly helpful tool it once was. Takes a high antenna to be useful at only 4 watts legal anyway.
6
Antennas / Re: antenna theory - fundamentals
December 16, 2019, 07:17:07 pm
Antennas are like guitar strings.

Antennas radiate magnetic fields like a guitar string vibrates and pushes sound pressure waves away from the length of the string.
7
For my journey back into 2-way radio I give great credit to the low cost and highly educational nature of software defined radio.
All one needs is a $25 dollar USB SDR receiver for your pc, and a piece of scrap wire. My favorite software is free and learning was totally at my own control.
Dongle used: RTL-SDR
Software: SdrSharp (sdr#)
Other software works too, but sdrsharp has worked best for me.
Even after getting my ham ticket, I still make great use of my SDR setup to visually see what's on the air.