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A little while back there was a heads-up and ensuing discussion on
the Melbourne Wireless mailing 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/406579bb02b2526c273fc0a87f990748/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
(which I now strongly suspect to be a 5dBi 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 [2] connector on the antenna side and a
standard-SMA [3] connector on the radio side. Included is a
SMA-to-RP-SMA RG-316 pigtail [4] 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. Refer to PowerAndGainToDecibels [5].
I've been putting the amp through it's paces, and have compared it to
my Longreach [6] 1 watt amp.
I have a Superpass [7] 8dBi omni on top of a 13 metre mast at my node
- Node GMR [8]. It was connected to a SVEC [9] AP inside my house, and
I used to have the Longreach amp inline - in locally powered mode. I
shelled into Node GES [10] and ran Wavemon [11]. 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 with the DSE Amp
inline:
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 [12] 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 [13]-to-N-type [14] pigtail [15] 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? -- DanFlett [16] 170304
Update: 03/09/2006 On the subject of these Dick Smith Amps.
I (another mw member), bought one an amp that looks (and its specs)
are exactly as the dse one.
There obtainable for around $130-$160 from citytechnology.com.au and
have a brand name of micro-beam
Links:
------
[1] http://www.dse.co.nz/isroot/dse/images/products/XH6825~LGE.JPG
[2] http://melbournewireless.org.au/?RPSMAConnector
[3] http://melbournewireless.org.au/?SMAConnector
[4] http://melbournewireless.org.au/?Pigtail
[5] http://melbournewireless.org.au/?PowerAndGainToDecibels
[6] http://www.interway.com.au
[7] http://www.superpass.com
[8] http://melbournewireless.org.au/?NodeGMR
[9] http://melbournewireless.org.au/?SVECWLAP
[10] http://melbournewireless.org.au/?NodeGES
[11] http://melbournewireless.org.au/?Wavemon
[12] http://www.knoppix-std.org
[13] http://melbournewireless.org.au/?SMAConnector
[14] http://melbournewireless.org.au/?NConnector
[15] http://melbournewireless.org.au/?Pigtail
[16] http://melbournewireless.org.au/?DanFlett
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