LeroyPatrol (25-02-19),Mr 672A (25-02-19),mtv (24-02-19),tristen (25-02-19)
I recently bought a replacement c band lnb from Strong (SRT L928) to replace an ageing Zinwell destroyed by lightning:
This is a new model which replaces the SRT L926 and appears similar in all respects but one, a lower noise figure of 15K compared to 17K for the earlier model.
At first I was disappointed with its performance compared to the Zinwell but then the penny dropped - - -
I had installed it with its supplied scalar ring, replacing the AV COMM scalar rings which were originally supplied with the dish centuries ago - well, almost!
The AV COMM had accommodated all subsequent LNB's I have used over the years, including the late unlamented Zinwell. They all fitted well, with some requiring sleeves to accommodate slightly different external LNB diameters. The remarkable thing was that they all had near identical internal diameters and therefore presented no step edges to act as microwave deflectors.
A quick check revealed this was also the case with the new Strong, and in no time the old AV COMM scalars were back in their familiar place - and the fainter channels now boomed in!
I have no real explanation as to why this is the case, but assume the much larger diameter of the AV COMM, coupled with deeper baffle rings is more suited to large dishes.
In conclusion, the SRT L928 is an excellent LNB, but it is (in my application) handicapped with very ordinary scalar rings.
4.6m C band dish, numerous Strong boxes, GTsat V8 Nova and even an old BMAC somewhere ---
LeroyPatrol (25-02-19),Mr 672A (25-02-19),mtv (24-02-19),tristen (25-02-19)
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having been there and wondered i got out the old books and to my surprise it worked out to be the simpliest of answers mathematics , AVCOM have worked things out on maths ie 300 over the frequency in meghz equals length not as the chug copy for minimum product required to get a result the depth is a rejection of unwanted freqs into the lnb and more of the correct freqs means a better piccy
jbeatty (25-02-19)
These LNB's are made by Shenzhen Gospel available in various brands label including Strong's. They use Phase Lock Loop oscillator meaning the frequency won't drift. The longer throat also helps with reception. They come in Narrow Band 3.7 to 4.2 which helps with the European buqet (3700) on Asia 5. and also available in Wide 3.4 to 4.2 for Vinsat and Chinasat 10.. The only let down is the supplied thin scalar ring, which disadvantage the LNB performance, so best to discard the scalar ring and use your old thiker ring.
Last edited by B52; 25-02-19 at 02:32 PM.
LeroyPatrol (25-02-19),Supermega (05-03-19)
Yep. Quite a difference between the old and the new. Note how the Strong internal diameter matches the AV COMM scalars perfectly.
I wrapped some all weather tape around the Strong LNB to centralise it. It's a tight push fit so no other fastening required. this simple "sleeving" has worked well for other LNB's in the past:
Not that i'm a good photographer by any means but my shadow gives an idea of scale. Dish is pointing at Measat 3 (my westernmost sat)
4.6m C band dish, numerous Strong boxes, GTsat V8 Nova and even an old BMAC somewhere ---
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