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Sunday, 10 March 2019

es'hail-2 dish feed


Very much inspired by the fun back here, I figured it would be great to try and make a better single feed for the dish for both bands.

This seemed to be just the ticket.

Not this needs to be plumbing, not electronics!

I paid a visit to fellow ham and insane constructor Ian, G4EVK; who has some amazing model making equipment and a good plumbers blowtorch!

Here's some photos of the build:

I'm waiting for a "rocket" LNB that I hope will fit on the end of the waveguide (read 22mm pipe) using a compression fitting, I have also used the trick from here to check the 2.4GHz return loss - after a little bit of bending it's now looking spot on.

Yesterday I very nearly mowed the lawns, today we woke up to this:

Let it snow.....

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** UPDATE **

I have used the lens from a "rocket" LNB on the front of the feed and removed the feedhorn from an Octagon LNB (with a hacksaw) and connected it all together with a 22mm compression pipe connector and some waterproofing with some silicone. I have also modified the LNB to take an external 25MHz signal (as above):

I've used the same trick I used back here to measure the return loss on 2.4 GHz and its around 20dB; I have also lashed up the receiver on the 10GHz downlink and that is working just fine.

Now, how on earth can I weather proof this?

Miss Maggie and Miss Pepper Cat seem to be economising by using the same bed? Bonkers.

Local conditions....

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  1. I built the same feed system and tried three different Dielectric lenses. One like yours from a Rocket LNB and a pair that were machined by a friend. The rocket one had zero effect... didn't work, while a lend machined from NYLON6 made a considerabledifference, but the best of all was another lens machined from a scrap piece of unidentified green plastic rod. It was far and away the best performer making for an easily audible improvement in the downlink signal. I can't normally notice 1 S-Point (6Db) and this green lens made an easily audible difference. The recommended NYLON6 lens material is fine, but we reckon the green stuff (from burn tests etc) is PE Filled Green Nylon Rod. Take a look here... and best of luck! 73 Al. GM1SXX.

    1. Thanks! I'll get some of your recommended plastic and try.