GeoSat Pro 90 Dish Vs DMSI HotDish90

[sattech64]

I have both of these dishes and for some reason, I can't get my GSP to come anywhere close to the performance of the HD90. I have the GSP on a fixed dish setup currently but I have tried it on the same pipe as the HD90 (motorized) is located. I have tried numerous LNB's as well as every configuration of the assembly I can find. Are there any known pitfalls to the dish such as a step I'm missing during assembly or setup? I know the GSP is slightly smaller than the HD 90 but not by enough to cause the problems I am running into. I am using it currently pointed at SES2 and there is quite a bit of Q change between the two dishes, for example making the difference of LPB locking on the HD and not on the GSP.

Thanks ahead of time for any suggestions

WT

[el bandido]

Where did the Geosat dish come from, and who put it together? There should be little if any signal difference between those two dishes. It may or may not help to post a clear picture(s) of the front of both dishes that shows the lnb and its supports.

[sattech64]

The dish came from Hypermegasat and I assembled it. I was thinking the same that the difference between the two should be very little. I'll have to take photos of the install later for reference. I don't see any way to make much of a mistake assembling the unit but thought I would check none the less :)

Wt

[Terryl]

The overall RF gain on the GeoSat dish is 39.6 dBi at center frequency, and what I have seen the overall gain on the HD90 (what I can find) is 40.32 dBi, .72 dB difference, this is not much, but every bit helps.

Receive beamwidth for the GeoSat is 1.8 degrees, but I cant find the same spec for the HD90, 1.8 degrees is a small receive aperture, this means you would have to right dead on to both the satellite and the LNB mounting to get the max signal out of that dish.

[el bandido]

The overall RF gain on the GeoSat dish is 39.6 dBi at center frequency, and what I have seen the overall gain on the HD90 (what I can find) is 40.32 dBi, .72 dB difference, this is not much, but every bit helps.

Receive beamwidth for the GeoSat is 1.8 degrees, but I cant find the same spec for the HD90, 1.8 degrees is a small receive aperture, this means you would have to right dead on to both the satellite and the LNB mounting to get the max signal out of that dish.

What is the name of the laboratory that tested and calculated the gain for these two dishes?

[MikeB]

I'd be willing to bet that if you checked it, the GSP dish is "popped" out of shape. I've got a couple, and they are REALLY good dishes.

[eastof111]

Mine arrived slightly modded by the delivery driver and it still works as well as my Hotdish.

17177

[sattech64]

The overall RF gain on the GeoSat dish is 39.6 dBi at center frequency, and what I have seen the overall gain on the HD90 (what I can find) is 40.32 dBi, .72 dB difference, this is not much, but every bit helps.

Receive beamwidth for the GeoSat is 1.8 degrees, but I cant find the same spec for the HD90, 1.8 degrees is a small receive aperture, this means you would have to right dead on to both the satellite and the LNB mounting to get the max signal out of that dish.


You are exactly right on being spot on! Very tedious adjustment get a lock and if you breathe you lose it.

[sattech64]

I have checked the dish with the string test and they all meet perfectly in the center. I have a strange feeling that something is whacky on the feed arm. The pole is plumb and the dish has been tried on different confirmed working mounts with no difference. I lined up a different LNB day before yesterday and 7.6 Db C/N was the best I could scrounge on the CNN carrier on SES2 according to my Super Buddy meter and for kicks tried it with my FS1 and it was within 1 Db of the SB

For what it's worth I have attached some photos for reference.


Thanks to everyone for the ideas!

[el bandido]

What is the name of a city that is close to your location?

[sattech64]

I’m located just about nowhere lol. Abington va roughly 30 miles. Bristol Va/Tn is roughly 40 miles. I’m located in Whitetop Va You might locate that on a map. I can give you coordinates if you need

[el bandido]

Just curious of the lnb skew, which looks correct for 87w at your location.
The pictures are dark, but there probably isn't much to see anyway. If the lnb arm is not set at the correct distance from the dish, then there will be signal problems.
There should be two side mounts or side arms that hold the lnb mounting arm straight on the dish. There should be a bolt that runs through the lnb arm and joins the two side arms to the lnb mounting arm. You may try removing this bolt which disconnects the side arms, then slowly move the lnb arm towards the dish and away from the dish. Do this very slow and watch the signal meter while you are doing this. If the lnb is mounted correctly, the signal will not increase when the side arms are disconnected and the lnb is moved.

Check for correct dish alignment by slightly raising, then lowering the top, bottom, and both sides of the dish. Watch the signal meter while doing this. The signal will drop each time the dish is moved in any direction if it is aligned correctly.

[Terryl]

What is the name of the laboratory that tested and calculated the gain for these two dishes?

Many to choose from, [Only registered and activated users can see links]

We had to do performance checks on all our RF systems, then the system is taken to an independent lab and have them verify the test data, then all that data was sent to the FCC labs where they issue a go no-go for sales and installation.(FCC ID tag is issued if needed)

[el bandido]

Which lab(s) tested the two 90cm dishes in this thread? Most likely, the answer is None! GeoSat and HotDish just write in whatever spec they want knowing it will not be cheap to check it.

[sattech64]

Sorry for the dark photos. I knew if I didn’t get them last night I would be doing it in today’s monsoon. I have it peaked for all it’s got in it right now but I will remove the support bolts and give that a try. I have a feeling it’s in that area. I noticed the OS Mio 4K was showing 7.6 db c/n tonight on LPB and with low cloud ceiling and rain. Cutting it pretty close 😀. Thanks for the suggestions and as soon as this dreary monsoon weather breaks I will work on them

[MikeB]

I think it's possible to install the side-arms flipped the wrong way, which would torque the lnb arm into the wrong position. Double-check that possibility. Also, that lnb holder you are using doesn't look original to me. Did you get the dish brand new, or did you ever change that holder?

[sattech64]

Yes the dish was purchased new. I think the feed arm issue is probably where it lies also. Thanks for the idea! As soon as it warms up a bit here I'm going to have a look at that today. Finally some sunshine for a change LOL

Thanks again!

[sattech64]

Today turned out sunny and warm so I was able to work with this problem child a bit.
I disassembled the support arms and moved the feed arm up and down and to both sides. I was able to gain a db or so with this so I shimmed things to stay at this orientation. The biggest change came when I swapped the older Avenger DRO LNB for a GeoSat Pro S1Pll LNB. That move gained a little over 2 DB on 11960 and close to three DB on 12076 and 11760. I haven't tried moving it to any other birds yet but given it does this well on SES2 it should perform close to this benchmark on any other location that I have decent LOS. LOIF frequency error was less than 100Khz for the SL1 but I forgot to check the Avenger DRO. Just for grins, I checked polarization with my SA, and my best quality was almost 2 degrees higher than the spec at 7.3 degrees. Until I check this against the HD90 I'm inclined to believe it's as good as it gets with this one. The one thing I did forget to do was move the LNB around the focal point by hand to see if any noticeable change could be detected but the feed arm support test should have been very close to what that would have shown.

Thanks to everyone who took the time to participate in this "project" Hopefully I can repay the favor in the future

Thanks
Wt