[MLB-WIRELESS] Dick Smith NZ 500mW amp

[Dan Flett]

Hi Diddly Ho,

A little while back there was a heads-up and ensuing discussion on this
list about a 500mW 802.11b/g amplifier that Dick Smith New Zealand
sells.  Well I bought one.  This is the item in question:
http://www.dse.co.nz/cgi-bin/dse.storefront/40577b840d495de4273fc0a87f99
071e/Product/View/XH6825

I ordered it in early February and received a customer code from the
website but no email confirmation.  After a month I just assumed that
the order didn't go through.  Then on 10th March it arrived.  The
invoice is interesting as it appears I haven't been charged NZ GST on
the item, even though the "tax code" says that I have.  I paid NZ$264
for it, which is AUS$240.  I also bought a 7dBi magnetic mount antenna
for NZ$40.89 and postage was NZ$25.11.  The grand total was AUS$298
charged to my credit card.

The Amp has a RP-SMA connector on the antenna side and a standard-SMA
connector on the radio side.  Included is a SMA-to-RP-SMA RG-316 pigtail
so you can plug the amp into your AP.  The Amp runs on a 6V DC supply -
don't know what the current draw is though.  The manual claims a 17dB
increase in transmit gain and a 10dB increase in receive gain.
Interestingly, the Longreach 1 watt amp claims a 15dB increase in
transmit gain and a 16.5 increase in receive gain.

I've been putting the amp through it's paces, and have compared it to my
Longreach 1 watt amp.

I have a Superpass 8dBi omni on top of a 13 metre mast at my node - Node
GMR.  It was connected to a SVEC AP inside my house, and I used to have
the Longreach amp inline - in locally powered mode.  I shelled into Node
GES and ran Wavemon.  He has a 13.5 metre mast with a 25dB conifer on it
pointed at me.  We run on Channel 4.

Here are the Figures from Node GES
				SVEC/No Amp	SVEC/Longreach
SVEC/DSE-NZ
Link Quality		54/92		80/92			78/92
Signal Level (dBm)	-66		-53			-55
Noise Level (dBm)		-100		-100
-100
Signal-Noise Ratio (dB)	+34		+47			+45

I now use a Minitar as my AP, here are the figures:
Link Quality		78/92
Signal Level (dBm)	-53 (dips into -52)
Noise Level (dBm)		-100
Signal-Noise Ratio (dB)	+47 (dips into +48)

As a control I also ran my laptop in my office with an Enterasys card
(using the internal antenna) and ran Knoppix STD on it.  Here are the
wavemon figures:
				SVEC/No Amp	SVEC/Longreach
SVEC/DSE-NZ
Link Quality		20/92		28/92			27/92
Signal Level (dBm)	-75		-65			-66
Noise Level (dBm)		-93		-92
-91
Signal-Noise Ratio (dB)	+15		+27			+25

These figures from my office are a bit rubbery because I was sitting
right next to the laptop and there was a lot of fluctuation.  I did
stare at the screen for a long time however and wrote down the most
stable figures.

I don't have a SMA-N-type pigtail yet so I can't plug the amp into any
of my cards.  So I have yet to run wavemon on an interface that actually
has the amp plugged into it.  I plan on doing so soon so I can get a
good idea of the noise figure of the DSE amp.

Any other suggestions for testing?

I've put this post in the wiki as well, under
http://melbourne.wireless.org.au/wiki/?DickSmithAmplifier

Cheers,

Dan

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