Kostats touched on one important factor. No two stations are the same.
And while the problems are all in the same sets of families, the
specific cause and specific fix varies. It can take a lot of time to
determine what the source of a problem is and get it mitigated somehow.
There are lots of variables and the mixer-type of noise sources really
can make you crazy tracking them down because they can come from almost
anything electrical, electronic or metal in the environment up to quite
some distance from the antennas.
73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com
On 28-May-18 11:46 PM, kostas sv1dpi wrote:
I know it can be done without interference. In EP6T were I was a
member, we were working the 1st day with a hexbeam on 10, 15 and 20m!
Interference in k3 was less than an 1S unit! We used 4O3A triplexer
and high power band pass filters and w3nqn low power band pass.
In SZ1A (my club) we use dunestar low power band pass filters, stubs
after the amplifier and monobanders. Also the interference is accepted
except between 20 and 10m (not very usual situation and not bad but
more than we would like).
My experience from SZ1A says that your problem is a switching power
supply. Some years ago we had an ethernet switch. We tested the
switch's power supply and it was quiet during rx. But the interference
from 20 to 15 was S9! Same between 40 and 20m. Searching I found the
problem to be the switching power supply. It re-transmits the noise!
An easy search to find such a problem is to increase the power and
watch the problem. For example 5w - no problem, 50w - no problem, 100w
- no problem, 200w -S9 noise. This is not normal. If the problem was
because of bad filtering, the interference noise would be more linear.
For example 5w - no problem, 50w - S1, 100W S3, 200W S5 and goes on.
73 Kostas SV1DPI
Στις 29/5/2018 05:32, ο Timothy Coker via TowerTalk έγραψε:
Is anyone out there operating high power SO2R or Multi-Op without
interstation interference (besides being on or very near a harmonic)?
I read reviews of various antennas, new filters, etc of having
non-existant issues. However, in my limited experience it seems that
tribanders will have these issues even with the latest high power
triplexors and band pass filters. Even problems will arise at
multi-tower stations with monoband yagi stacks and/or different
direction facing yagi's.
Has anyone got the ability to say that they are trouble free on their
various band combinations?
For instance, at home I have lots of interference when receiving on
15m and while transmitting on 20m. Same goes when receiving on 20m
and transmitting on 40m. For me, it can be both direction and/or
antenna limited depending on what band combination and which
tribander that I take out of the stack.
I'm curious about the true confessions that other operators have
about what they are dealing with when transmitting on multiple bands
at once? Have some of the stations got this under control? If so is
it mainly the big property owning stations with many towers or have
guys on 1-2 tower setups quelled this also?
73,
Tim / N6WIN.
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