modified BSC-621 update

[truckracer]

I recently modified my BSC-621 since I felt lke it had less than stellar KU performance. I tuned and tuned my 10 foot dish using a pansat 9200 HD FTA receiver.

I always had a theory that the internal scalar ring on the ku lnbf was creating too much signal rejection. C band was good but ku never seemed great. I checked dish alignment, skew, focal point , etc.

I looked down the lnbf to make sure that ku was lined up with the c-band H and V probes. That checked out good.

Here is what I did:
I used aluminum foil duct tape to neatly cover the internal ku scalar ring located in the bottom of the feedhorn. I used an exacto knife to cut out the center hole so the ku signal could get into the ku portion of the lnbf.

I neatly trimmed it on the edges. No foil tape can hang over the edges because that scalar is a tight fit into the c-band lnbf part of the unit.

After re- assembly I tuned the lnbf and KU was much improved.

From a scientific standpoint this MAY have helped or maybe I just got it all better aligned. I am not for sure but I have great KU band signals now.


That foil tape may be a problem when the weather gets hot, since this is an experiment I will have to think of a permanent solution later.

 

[tvropro]

Scaler rings are designed to choke off out of focus energy. There may be an incompatibility between your dish and that feed 's design which is why this mod worked. If it gives you desired results it's all worth it. Experimentation is half the fun

 

[truckracer]

bsc-621

It is supposed to work with prime focus dishes. I could not understand why they used a second ring inside for ku since the dish already has the primary ring that holds the lnbf in place.

I know that the traditional C-band polorotors don't have any additional scalars. Just the one primary ring that holds the unit on the struts.

I am basing my theory on this. I will play more with it later today.
I am thinking the additional ring is choking more signal unneccesarily.