GEOSATpro Can no longer receive RTV on 87 and 137 W - HBCD modulation No Signal !

TvMind

SatelliteGuys Family
Original poster
Sep 26, 2011
61
5
Montreal
I've lost all dvb-S2 signals on 87 W (those listed on Lyngsat/ Mike Kohl). The signal quality is zero and the info says "HBCD" modulation/ By source (resolution).
Both on 87 and 137 W. DVB-S signals are fine i.e 360 North and Alaska nets. I checked the signal , DVB-s that is, on a second unit and they are decoded fine. I did the usual reloading of firmware and reboot procedure but nothing helps. Another "clue" is that the RTV feeds have erratic signal quality - by that I mean they bounce back and forth between 35-70 on the Quality meter (one of these days somebody is going to have to explain to me the difference between signal and quality). The DVB-S signals are solid, don't waver on the same satellite. Again this is an issue with RTV only, other DVB-S2 signals i.e NHK Japan on PAS 9 is solid 70 (Q). Has anybody else experienced this problem ? It also seems to improve as the unit warms up so I suspect a thermal problem somewhere. A possible related question is the weak 83 W (AMC-9) RTV ku signals.. I peaked my 10' this summer -spent two months meticulously getting everything as best I can. The only other change I made was getting a newer Corotor II plus Wideband (Int'l) with the dielectric plate integrated in the feedhorn. Now I know this adds some loss 1 db from what I've read , but it seems that I lost 3db or more.
New ribbon cable, new lnbs' (NJR ku 950 khz LO stabilty <---- could this be the cause of the 'wavering DVB-S2 RTV signals ?). Also Metv is gone from Anik , same issue "no signal and modulation says HBCD, by source resolution". Also the ku reception is now very fussy on the motor actuator, one or 2 units and the signal disappears. I have a feeling it's this 'fussy' new Corotor. I was going to buy a regular, non-international one but this one was on special - but I never imagined it would cause such troubles as it has. Oh one more thing, I did a blind scan on 137 W and received RTV alternate set there, (not listed on Lyngsat btw) so I am lucky. I'd like to get back my strong ku signals on 83 W so that I could record the older DVB-S signals on the Pioneer DVR. I know I could setup a separate dish fro ku, but I used to have them fine on my SAMI 10' footer for years.

I have a sneaking suspicion that RTV symbol rates or something is causing this GEosat to freak out. Can anyone else chime in here and share their experience ?
Btw I added coaxial composite video and stereo audio jacks to the back of the unit - and no no I didn't mess things up inside - I'll post pics if anyone is interested. I also added a copper grounded plate underneath and moved the unit far away from the set, that helped a bit with the RFI interference but I'm still not satisfied. Yes I will come out of the dark ages and get HD tv but liek I said I'm only doing this for classic tv (480i).

cheers,

TvMind
 
Merci monsieur. But please read the rest of that wordy thread above concerning the Corotor II Plus Wideband 'fussiness' and weak Ku signals.
 
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TvMind, I'm getting the RTV on my Micro but it's not a steady signal due to tree limbs. By next month I should get then to stay in. Do you have another receiver to try and see if you get different results? I usually swap the Micro with another receiver I have to compare results..
 
This may be a dumb answer/comment --- dielectric plate ... in the feedhorn.... it that not for circular signals??

Yes it is, and it cuts down the signal quality by 1/2 or more. So, that's just enough to make receiving S2 signals problematic. S2 is hard enough to receive when everything is perfect, much less using a feed that's not even made for regular American FTA sats. That plate can be removed, even if it's one of the ones built in I've heard of people tearing it out.
 
Yes it is, and it cuts down the signal quality by 1/2 or more.

According to Chaparral the loss is closer to 1 db, not half or 3 db as you mention. Now I'm not crazy enough to 'tear' out the dielectic slab without damaging the antenna probe.
RTV on ku is weak, and it's SD not HD (S2). How much loss does the feedhorn cap contribute ? I'll pop it off and see. I've seen some commercial installations that leave them off despite the bug warnings.
 
Hi Blind,

Thanks for chiming in here. No limbs or obstructions here for that satellite. No I don't have another HD box to try. I was really keen about the new Traxis but everybody (dealers) are telling me to stay away...hmm. No the 'bouncing signal' is a Geosat DVB-S2 issue, the standard DVB signals say on 137 W (Alaska nets) are all solid ! So disappointed with this HD stuff, especially since it's totally unnecessary (480interlaced) for classic tv shows.
 
According to Chaparral the loss is closer to 1 db, not half or 3 db as you mention. Now I'm not crazy enough to 'tear' out the dielectic slab without damaging the antenna probe.
RTV on ku is weak, and it's SD not HD (S2). How much loss does the feedhorn cap contribute ? I'll pop it off and see. I've seen some commercial installations that leave them off despite the bug warnings.

Ok, I think you misunderstood me. I don't believe Chaparral in this case, because a dielectric plate inserted in a feedhorn to convert to circular signals is going to lose 3 db minimum, because it cuts 1/2 the signal level. That's just how they work, and you can't beat physics no matter what you think. A 3db loss is about the same as using a 7~ foot dish, instead of a 10 foot dish.

Maybe they can calculate a 1db loss in a perfect world, with a 20 foot dish where there's so much gain to start with or something, but it's false advertising to say there's only a 1db loss in every situation. Even so, 1 db equals a 26% signal loss in a perfect world.

If you still insist on trying for circular signals, Google "c band waveguide polarizer".
 
No absolutely, you can't argue with physics. So has anybody tried this, removing the dielectric I mean without damaging anything ?
I only went for this international feedhorn because it was on special and was practically new, if I knew it was going to cause such a significant loss and all the added grief I would plonked down the extra dineros and bought a regular Corotor II Plus.

Thanks Primestar for your sensible comments here.
 

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