LinkBack Thread Tools Search this Thread Display Modes
Prev Previous Post   Next Post Next
  #22   Report Post  
Old April 24th 15, 01:22 PM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Nov 2012
Posts: 989
Default A Top Band 1/4 wave vertical?

On 4/23/2015 10:38 PM, Jeff Liebermann wrote:
On Thu, 23 Apr 2015 19:25:21 -0700, Jeff Liebermann
wrote:

On Thu, 23 Apr 2015 18:32:56 -0700, Jeff Liebermann
wrote:

Helium previously costs about $8/liter but is now running about
$20/liter thanks to the helium shortage. That's $14,600 for 730
liters. Are you sure you want to do this?


Hmmm... that can't be right. The problem is that I'm getting prices
for helium that are all over the map. For example:
http://www.reuters.com/article/2013/09/19/us-helium-shortage-analysis-idUSBRE98I0AN20130919
"... spot price of liquid helium has jumped to $25-$30 per
liter from $8 last year."

http://www.crainsnewyork.com/article/20140126/FINANCE/301269974/helium-shortage-deflates-party-city
"prices have doubled since 2006, to $6.13 per-cubic meter,
according to the latest figures from the U.S. Geological Survey."
1 cubic-meter = 1000 liters, so that is $0.00613/liter which seems
rather low.

http://minerals.usgs.gov/minerals/pubs/commodity/helium/mcs-2014-heliu.pdf
"The estimated price range for private industry’s Grade-A gaseous
helium was about $7.21 per cubic meter ($200 per thousand cubic
feet), with some producers posting surcharges to this price.
1 cubic-meter = 1000 liters, so that is $0.00721/liter, which agrees
with the previous article, mostly because the price came from the same
source.

Ok, let's try party helium:
http://www.sfparty.com/products.php?product=Helium%3A-Balloon-Time-Disposable-Helium-Tank-Purchase
$55 for 14.9 cubic-ft.
14.9 ft^3 = 422 liters
$55 / 422 liters = $0.13/liter

Does anyone have the real price of helium?


Never mind. I see the problem. There's a big difference between
medical grade helium used to cool MRI machines, and the helium sold at
party stores for filling balloons.
http://www.bbc.com/news/uk-19676639
The party store helium is recycled from the MRI gas and is mixed (i.e.
diluted) with air.
"The helium we use is not pure," he said. "It's recycled from the
gas which is used in the medical industry, and mixed with air.
We call it balloon gas rather than helium for that reason."
Mythbusters found this out the hard way when they tried to lift a 3
year old with a large number of helium balloons.
http://www.discovery.com/tv-shows/mythbusters/videos/balloon-girl-minimyth/
They needed over double the number of balloons needed to lift the kid
mostly because they used party balloon gas instead of the pure stuff.
That also explains the price difference.


You are also confusing gaseous helium and liquid helium. Not much in
common.

--

Rick
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Which is better: 5/8 wave vertical or J pole? David Antenna 29 November 20th 10 03:50 PM
20m 1/4 wave portable vertical K7ITM Antenna 1 April 24th 08 08:13 PM
New program - 1/2-wave vertical Reg Edwards Antenna 6 May 13th 05 04:29 PM
5/8 wave 6m vertical [email protected] Antenna 7 February 15th 05 03:02 PM
1/4 wave vertical vs. loaded vertical Dave Antenna 6 May 26th 04 01:28 AM


All times are GMT +1. The time now is 04:35 PM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017