David, looking at that link and plots you sent, that radio will not meet
community and other band user spectral purity expectations.
At UHF, It needs to be better than -70dBc in an SSB Bandwidth immediate
adjacent
At 1MHz away, -110dBc in an SSB BW...
and proportionally better at lower frequencies....
-40dBc in band you will make alot of other radio amateurs unhappy...
Here is a worked example from your 144.5 plot.
+10dBm - 40 = -30dBc in SSB BW
Now, how about an SSB users 10km away line of site (-95dB), say 0dBi to
0dBi,
you put -30 - 95 = -125dBm noise in his receiver, an effect desense of
about 18dB.
and that is only with +10dBm TX power.
g
On 10/08/2020 7:52 am, David Rowe wrote:
With the addition of a LPF I believe it meets the spectral purity
requirements of the Amateur LCD on 2M:
http://www.rowetel.com/?p=7207
and on HF:
http://www.rowetel.com/?p=6317
- David
On 10/8/20 6:50 am, glen english wrote:
except that the Pi transmitter has unacceptable spectral purity.
On 9/08/2020 7:18 pm, Adrian Musceac wrote:
Thanks David for the news.
One question: how high can the Pi transmitter go in frequency?
Our 70 cm band is pretty crowded, but the 23 cm band and 2305-2400 MHz
bands are underutilized and we want to make use of them. The Pi/RTL
system is a good candidate because of price.
Adrian
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Glen English
RF Communications and Electronics Engineer
CORTEX RF
&
Pacific Media Technologies Pty Ltd
ABN 40 075 532 008
PO Box 5231 Lyneham ACT 2602, Australia.
au mobile : +61 (0)418 975077
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