T90 dish and bandstacked LNB's?

[pendragon]

All the LNB's my distributor shipped me are of the stepped plate kind (the left ones in your picture). Been trying to find a DishPro PN: 151019-NS but find a distributor up here stocking them. (ideas?)

Almost all of my DP circular LNBFs were surplus from Superdish assemblies I bought on eBay to get bandstacked FSS LNBs (11.7-12.2 GHz) for my T90s. All had dielectric plates inside. I reversed a few for our DN subscription and only recently found a use for the rest - I published a thread on adapting their feeds to the FSS LNBs. I would have offered them, but I now only have a few left. There are usually plenty of cheap DP LNBFs on eBay, and perhaps you can get a seller to make sure they send the right type.

The case on mine is quite wide on the neck, basically wouldn't work on the T90's LNB holders without removing them from the case. Do the one ones on the right in your picture which you modify have a thinner neck or do you have to mount them outside their cases also?

I tossed the cases as they're mostly decorative, That leaves a neck that is much smaller than the T90 LNBF holders. I wrapped a thin strip of rubber around the necks of the feeds to get a tight fit.

 

[MetaMan]

No Modifiable LNBF is Distribution in Pacific Northwest

I gathered somewhere around 50 of the DishPro LNBFs (dual outputs) that were designed for one orbital location. Only one had an aluminum stepped plate and it looked much older than the rest. I never spent any time on it because it was very noisy. The stepped plate looks like it would require fairly delicate surgery to convert to reversed polarity.

See the attached photo for a comparison of these two types. The one on the left has the aluminum stepped plate while the one on the right has a plastic dielectric plate. Note the stepped plate LNBF is much thicker at the base, but inside the plastic shell this may not be apparent. However on mine there are two little screws mounting each F-connector for the stepped plate version, while the dielectric plate unit uses only a nut on the connector itself. As I have only one of the stepped plate models, I can't say whether these characteristics are definitive. However all my dielectric units are alike and are certainly easy to modify.

I've checking in with several distributors in the Pacific Northwest and none have the style shown in the right side of the picture. One pointed to another F-Connector difference. The blue dialectric being Dish Networks current standard to ID high frequency parts 2.2 GHz. The white dialectric indicates to them that this is an early DishPro LNBF. So I'm now going to look farther afield for the units you have suggested.
Any comments are appreciated.

 

[MetaMan]

Beating the Dead FSS Horse

Almost all of my DP circular LNBFs were surplus from Superdish assemblies I bought on eBay to get bandstacked FSS LNBs (11.7-12.2 GHz) for my T90s. All had dielectric plates inside. I reversed a few for our DN subscription and only recently found a use for the rest - I published a thread on adapting their feeds to the FSS LNBs.

Just wanting to clarify something. You have converted polarities of DishPro LNBF's (DBS type Circular Polarization but w/Band Stacking) not just the DishPro FSS LNBF's (FSS type with Linear Polarization but w/Band Stacking for picking up 105 or 121)???

I specifically need to flip the polarity of 3 DishPro LNBF's for use in the T90 to pickup 110, 119 & 129. This is for a Dish Network subscription not FSS Free-To-Air off Linear Birds, and no need for 118.75 at present.

 

[pendragon]

Just wanting to clarify something. You have converted polarities of DishPro LNBF's (DBS type Circular Polarization but w/Band Stacking) not just the DishPro FSS LNBF's (FSS type with Linear Polarization but w/Band Stacking for picking up 105 or 121)???

I specifically need to flip the polarity of 3 DishPro LNBF's for use in the T90 to pickup 110, 119 & 129. This is for a Dish Network subscription not FSS Free-To-Air off Linear Birds, and no need for 118.75 at present.

Yes, I've flipped the polarizations for the circular (12.2-12.7 GHz) DishPro LNBFs. The only reason I brought up the old Superdish LNBs (105 and 121) is that a lot of these show up on eBay and they often have 1-2 of the modifiable DishPro LNBfs thrown in. That's where I got most of mine.

 

[MetaMan]

I've gone farther and farther afield, a number of US distributors and dealers, Sadoun. Most recognize the part externally but say they have not had the old style for quite a while. It appears that the dielectric depolarizers are the older design and the new ones are all based on the cast wedge type. Ebay has only one DishPro currently for sale but it has only one LNBF and no easy way to verify its type.

I suspect Dish changed the designs as a cost savings exercise in manufacture even if their is a slight loss in gain.

The Sonora stackers unfortunately stack hi at 1550 to 2050 MHz not Dish's 1650-2150 MHz so these won't work properly with a DPP 44. I've talked with their chief engineer but creating an alternative stacker is not a high priority for them right now.

I thought I could turn the wedge DishPro LNBF 180 degrees and I think the physics of depolarization would work but likely to obstruct signal between the primary and secondary reflectors.

Any other ideas?