By adjusting the polarization I was able to go from 5.1 to 9.8 on the
EBNo's. I just can't imagine why it would start acting up after this
many years of running fine.
Thanks for everyone's help.
Bill Tidwell
Jerry Mathis wrote:
On 7/13/06, Steve Runck <steverunck@kfnw.org> wrote:
So things were humming along fine, and then all of a sudden you started
losing signal? If so, I wouldn't throw the TI angle out too quickly
but,
of
course, a spectrum analyzer would remove a lot of the guesswork. I will
say
that in this day of multiple potential sources of interference, I
consider
a
TI filter to be standard equipment on my satellite dishes.
Steve Runck
Staff Engineer
KFNW AM-FM, Fargo, ND
701-282-5910, Ext. 235
steverunck@kfnw.org
Audio Streams at <http://www.kfnw.org>
> -----Original Message-----
> From: BILL TIDWELL [mailto:bill@waft.org]
> Sent: Wednesday, July 12, 2006 11:01 PM
> To: CRTech
> Subject: [CRTech] satellite ebno woes
>
>
> I'm currently pulling my hair out over a satellite problem.
> I have an
> ABR202 receiver on Galaxy 4 (I think) and the EBNo is down to
> 6 and the
> sync light is flashing and getting dropouts about 4/minute.
> I checked
> alignment, replaced the receiver, changed the LNB, and made sure the
> cable was OK. No bugs or water and it has a pretty clear shot with a
> 3.7 meter dish. The last thing I'm going to try is an
> attenuator, but I
> kinda doubt it will work. Symptoms haven't changed with any of the
> above. The new LNB is a 20 degree, 60 db gain, 5 khz stable
> osc. I set
> the M0 setting down to 2.0 so the unit is more tolerant of
> low EbNo's
> before dropout, but I need to find the real problem. Someone
> I talked
> to didn't think much of my TI hypothesis. Is it spectrum
> analyzer time?
>
> Bill Tidwell
> WAFT
>
> playing engineer for WAYR in Brunswick Ga. at this time.
>
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Two things I have found will make a radical difference in your Eb Nos:
1. Are you using an old Chapparel motorized feedhorn? Dump that sucker
and
get a single port single polarity (assuming you're not using the dish for
multiple feeds) feedhorn and put that on the dish. You might have to get
creative with the mechanical mounting, and you might need the adapter
plate
they sell separately to mount the feedhorn.
2. When you install the new feedhorn (and if you don't, then check
this with
the existing feedhorn), check the focal point adjustment. This is a
commonly
overlooked adjustment. I don't have the formula in front of me to
calculate
it, but I or someone can post it if you need it. If you have the dish
maker's specs, they should list it. When you have the distance,
measure from
the bottom of the dish (the bottom of the "bowl", that is) to about 1/4"
INSIDE the feedhorn. Again, you may have to get creative with the
mechanical
mounting of the feedhorn to get this properly set.
I suspect this may be your problem. With the focal point improperly
set, you
are picking up both adjacent satellite signals, and you're probably
getting
interference from an adjacent satellite.
By following the steps above, I increased the Eb on a signal we use
from 10
to 14. YMMV.
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