Lots of useful info - thanks to all! I think it would also be useful to
tell you about my RF situation here in the Land of Goshen to get the
best advice.
1. I live less than two miles from 3 transmitters:
-- WCMR 1270 AM. They are 5kW day, 1kW night. Bearing: NNW
-- WFRN 104.7 FM. 50kW. Same site as WCMR.
-- WSSM 97.7 FM. 6kW. Bearing: NNE
I usually have to switch on attenuation for the ELAD via software (and
for any other radio, really) when using my SE-NW longwire, which is
about 150 feet long. The rest are OK without attenuation. That's a lot
of RF flying about though. Growing up, we used to hear WCMR in all kinds
of odd situations - sometimes just an improperly-grounded audio circuit
would pick them up. I swear I heard their audio once coming from the
heater vents from the furnace...
2. There's a local RF noise source from somewhere - I think it's the
neighbor across the road, using some kind of battery charger on the RV
parked in their drive. We've talked briefly before, but I really need to
take the time to get with him and identify the problem, and offer to
help replace equipment or whatever it takes. It's pretty bad. Sometimes
it even covers up the Detroit Tigers game on Kalamazoo's WKZO on 590,
which upsets both myself and my brother, who lives next door. :^)
Whatever the interference is, gets sent out the power lines from the
neighbor's house, to the power pole. That section of power line is above
ground, so it radiates the noise locally to whatever will receive it.
What receives it best is MY power line coming to the house from the same
pole, which is also above ground. So I've got "dirty" power coming into
the house, as well as power lines transmitting it to the surrounding
area. To get away from all that noise, I have to have the antenna about
100 feet away from the house, on the opposite side from the road.
Anything closer gets saturated with noise.
Best solution is to identify the noise and eliminate it. The neighbors
are nice people - I think I can get him to help narrow it down. Perhaps
another solution would be to see if the power company will bury the
power lines for both of us. It would involve going under the road though
- the pole is on my side of the road.
As I get older, I'm finding myself more willing to spend the money for
"plug n play" solutions, but still, it's fun tinkering and rolling your
own. Just a matter of time for me mostly right now - there are some
other big time-consuming projects I need to address.
Thanks for all the feedback! (If this were an audio forum, that would've
been a pun...)
Mark
On 2016-10-07 11:25 am, Neil Kazaross wrote:
Unless one has some parts and wants to tinker, by far the easiest
solution
is go with a FLG100 from Wellbrook and a Vactrol from Colin. Both plug
and
play with cables and BNC connectors.
73 KAZ
On Fri, Oct 7, 2016 at 9:52 AM, Nick Hall-Patch <[email protected]> wrote:
Thanks Mark. I do think that your points about twisted pair are
correct,
and it would be intriguing to see if using twisted pair with the
FLG100
would make any further difference to the noise pickup. My suspicion
is
not, but it's only a suspicion. One of the things one seems to be
paying
for with the FLG100, as with the ALA100, is eliminating the concerns
about
noise being conveyed on the coax shield, which is what a balanced pair
will
do for you as well, at lower cost.
The difference for me has been the "out of the box" nature of the
FLG100
solution. There are costs and costs, and time has been a big one of
them
in my years as a DXer. And once the FLG100 is up, there's been no
tinkering with connections.
One thing that has made twisted pair not "out of the box" for me has
been
the lack of remotely weatherproof connectors at a price that is not
at
least a down payment on a FLG100 (and yes, the BNC on the coax is not
totally weatherproof, but a few inches of rubber tape is pretty
close).
If you have something that works well with CAT5 (banana plugs don't
count;
I've been troubleshooting with you, remember), then I am all ears.
I
think we discussed feed-through glands at one time. Is that what you
have
in mind?
best wishes,
Nick
At 11:58 07-10-16, you wrote:
I do love the way the varied interests in this hobby are propagated
through this club from member to member and I'm grateful for the
knowledge
and experience that's so freely shared.
One baby elephant in the room is Mark's antenna "ambience." If his
QTH
there in the Land O' Goshen is in a field of electrical interference
(and
perhaps significant local RF?), the noise gathered by the lead-in may
be an
issue best resolved not by common-mode choking but by "balancing" the
feed-lines.
I've bored folks to death by espousing the balanced twisted-pair
approach, in the form of Category cable (Cat 5, Cat5e etc) with an
impedance around 110 ohms. IMHO such a BALANCED transmission line
pretty
much eliminates stray pickup without the need for common-mode
choking.
Cat-5 sells for around $45/1000 feet...although if the budget allows,
I'd
go for STRANDED Cat-5.
As I type this I'm watching the Perseus on a D-Kaz facing mostly west
and
watching Seattle rolling in, here in North-Central Minnesota. Using
a 9:1
transformer and Cat-5 with a DXE RPA-1 in the shack and watching a
noise
floor of -111 dbm in 5 kHz, after the amplifier's 15 db gain.
An absolute YES to the Vactrol approach for the null component. The
design for that circuit somewhat obviates the potential for stray
common-mode pickup, so coax may work FB, but again...twisted-pair is
so
easy to implement.
As to mounting the RF amplifier at the antenna: I've tried the FLG
and
the DXE, planting them both at the antenna and in the shack. Like
Don
Moman, I can't really find any significant improvement...though in
theory
antenna-mounting of the amplifier is the better approach; weathering
issues
notwithstanding. (You would however, need a balancing transformer
after
the amplifier if you fed twisted-pair.)
A winterized installation at my site would include twisted-pair
lead-ins,
a 9:1 transformer and a Vactrol control, mounted in weatherproof
boxes and
the amplifier in the nice warm shack. Amazon fans have found all
sizes of
weatherproof boxes and wire feed-throughs:
At Amazon's greedy query, type in: "Cable Connect Waterproof Plastic
Case
Junction Box" and "Plastic Waterproof Cable Connectors"
Decent transformers (if you don't have strong RF nearby)
http://www.minicircuits.com/pdfs/T9-1.pdf
Now for the famous YMMV <g> Have fun Mark; continue to share your
experiences!
Mark Durenberger, CPBE
-----Original Message----- From: Mark Pettifor
Thanks for the advice guys - much appreciated!
I should also publicly thank Tim Tromp for getting me interested in
the
DKAZ to begin with.
Mark
On 2016-10-06 10:02 pm, Nick Hall-Patch wrote:
Agreed. They do cost a fair amount (mind you the exchange rate
with
the pound isn't bad right now), but are solidly built and work very
well.
Money well spent.
Nick
At 22:17 06-10-16, you wrote:
I very strongly recommend the Wellbrook FLG100LN, They go right at
the
antenna and replace your xfmr. Now what is picked up by the antenna
is
amped 22 dB whereas what is picked up by the coax is not amped at
all.
I have two of these and they've survived IL weather for over 3
years.
73
KAZ Barrington IL
On Thu, Oct 6, 2016 at 4:29 PM, Mark Pettifor <[email protected]>
wrote:
> For those of you who have DKAZ antennas, which preamp do you use? Do
> you
> find it makes much difference whether you put it at the antenna or in
> the
> shack?
>
> I need to "finish" construction on mine. Right now, I have two 470-ohm
> resistors alligator-clipped together for the null end, and a
hand-wound
> transformer (my first ever) on a core made of unknown material, to go
> from
> 940 to 50 into a 50-ohm feedline.... RG-8X, 150 feet. That is also
> alligator-clipped together. It was for testing, ya know? :^)
>
> It's been pretty good as is, but I want to get it ready to survive the
> winter.
>
> BTW, it's amazing the amount of noise just a short length of RG-8X
100%
> shielded coax will pick up. I have it mostly on the ground, but have a
> small part of the run overhead for now (30 feet?) so I don't mow over
> it.
> Thanks!
>
> Mark Pettifor
> Near Goshen, INdx.com
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Nick Hall-Patch
Victoria, BC
Canada
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