Just Sharing This AV-Comm Polariser + Zinwell lnbf

[s-band]

I did it to play with some old Dexcel LNAs and to improve the stability of the wide band modified Tit. The down-converter chip is on the verge of instability unless it has very good in/out isolation or a well matched input filter (which I removed for the wide band modified tit). The plan was to use a dual probe front end (e.g. Zinwell), take its output to a wider band filter to cover 3.6-4.8G and use this BDC. By separating the stages in different boxes, the chance of instability is reduced a bit. It may work over the whole range without switching the LO if used with the TBS6983.

Assuming the device at the base of the Y in the Zinwell is an amplifier, that's where I'd take the LNA output. However, I doubt it will be tuned well enough to cover the whole band. So, in blocks:
LNA > Filter > Attenuator? > Down-Converter It'll be low on the priority list though.

 

[John]

@s-band ... that Zinwell IC is a ZNBG3211.
Pic to follow

 

[John]

@s-band ... that Zinwell IC is a ZNBG3211.
Pic to follow

Zinwell innards Pics

 

[Channel Hopper]

As should any red blooded male.

 

[John]

..... these Cband lnbf's are a bit different on waveguide / probe design

 

[moonbase]

Hi,

Just received my AV-COMM barrel, flat scalar and Ziwell LNBF this morning (pics attached) and have a couple of questions if anyone can please assist?

When the flat scalar is fitted to the AV-COMM barrel with maximum barrel protruding from the scalar I have approx 2mm of barrel protruding. Is this sufficient protrusion to be able to optimise the signal re the barrel aperture being at the focal point of the dish and the scalar reducing background noise? I have some alternative wider collar C Band flat scalars that I can use if I need to get the barrel protruding further out from the scalar but I thought I would try the scalar that came with the barrel first.

On the Zinwell LNBF there is a numerical scale, presumably to be used for adjustment of the f/d to match the dish if the LNBF was placed directly in a scalar? Do we ignore this numerical scale on the Zinwell LNBF and just shove it home to the hilt with a dab of KY lube until the blue LNBF cap rests againts the internal collar in the AV-COMM barrel?

I need to get my spare Precision 1.5m rigged up and have a play with this lot ASAP.


Rgds

 

[John]

Hi,

Just received my AV-COMM barrel, flat scalar and Ziwell LNBF this morning (pics attached) and have a couple of questions if anyone can please assist?

When the flat scalar is fitted to the AV-COMM barrel with maximum barrel protruding from the scalar I have approx 2mm of barrel protruding. Is this sufficient protrusion to be able to optimise the signal re the barrel aperture being at the focal point of the dish and the scalar reducing background noise? I have some alternative wider collar C Band flat scalars that I can use if I need to get the barrel protruding further out from the scalar but I thought I would try the scalar that came with the barrel first.

On the Zinwell LNBF there is a numerical scale, presumably to be used for adjustment of the f/d to match the dish if the LNBF was placed directly in a scalar? Do we ignore this numerical scale on the Zinwell LNBF and just shove it home to the hilt with a dab of KY lube until the blue LNBF cap rests againts the internal collar in the AV-COMM barrel?

I need to get my spare Precision 1.5m rigged up and have a play with this lot ASAP.


Rgds

...Giggle giggle, apply the KY jelly and insert right up to the hilt, remember to remove any protection from the end of your equipment. Use a weather proofing cap at the scalar end of the polariser tube.

 

[Captain Jack]

What position should the barrel be in relation to the probes for circular and linear?

 

[John]

Hi,

Just received my AV-COMM barrel, flat scalar and Ziwell LNBF this morning (pics attached) and have a couple of questions if anyone can please assist?

When the flat scalar is fitted to the AV-COMM barrel with maximum barrel protruding from the scalar I have approx 2mm of barrel protruding. Is this sufficient protrusion to be able to optimise the signal re the barrel aperture being at the focal point of the dish and the scalar reducing background noise? I have some alternative wider collar C Band flat scalars that I can use if I need to get the barrel protruding further out from the scalar but I thought I would try the scalar that came with the barrel first.

On the Zinwell LNBF there is a numerical scale, presumably to be used for adjustment of the f/d to match the dish if the LNBF was placed directly in a scalar? Do we ignore this numerical scale on the Zinwell LNBF and just shove it home to the hilt with a dab of KY lube until the blue LNBF cap rests againts the internal collar in the AV-COMM barrel?

I need to get my spare Precision 1.5m rigged up and have a play with this lot ASAP.


Rgds

... Like this you mean, ideally you don't want to be using the adjustable scalar for attaching the dish feed arms on to. Adapt another scalar ring to do that..that will sit behind the front adjustable one. With front scalar removed, peak for max signal strength. Re-fit front scalar ring and adjust it's position on the barrel for best S/N which could also involve moving the barrel/scalar assembly together.
There could well be a need to skim further back along the barrel to achieve this, only trying will tell.

 

[John]

What position should the barrel be in relation to the probes for circular and linear?

Looking into the barrel the steps should be located vertically with the AV-Comm embossed letters running down the side of the barrel.
For Circular operation the lnbf F connector should be facing vertically downwards with the probes at 10 to and 10 past the hour. The skew mod allows you to fine tune this.
For Linear H/V use the barrel stops where it is but the lnbf is rotated to the more conventional position.... ie @12oclock & 1/4 past so to speak.

 

[Captain Jack]

Thank you!

 

[battenfan]

OT: These UFO hunters prefer adjusting their the scalar rings to a little less noise rather than maximizing gain.
Care and Feeding of a SETI Dish

 

[moonbase]

...Giggle giggle, apply the KY jelly and insert right up to the hilt, remember to remove any protection from the end of your equipment. Use a weather proofing cap at the scalar end of the polariser tube.

John,

Are you saying we remove the blue cap that came with the Zinwell LNBF and insert the Zinwell into the AV-COMM barrel without the cap? Then add a weatherproof cap at the scalar end of the AV-COMM barrel?


Thx

 

[John]

Thank you!

... Mr scopus has left me an answerphone message whilst iv'e been out walking the dog .... he's got his up and running and is very impressed with the results

 

[John]

John,

Are you saying we remove the blue cap that came with the Zinwell LNBF and insert the Zinwell into the AV-COMM barrel without the cap? Then add a weatherproof cap at the scalar end of the AV-COMM barrel?


Thx

Yes sir

 

[John]

OT: These UFO hunters prefer adjusting their the scalar rings to a little less noise rather than maximizing gain.
Care and Feeding of a SETI Dish

Yep thats correct, tune for focal point G spot to get you max sig strength .... then fit scalar and adjust for best C/N with very fine tuning of possibly moving both components to obtain best C/N.
Well thats the way i do it

 

[otokoc]

i am tested avcomm polarizer with 5 pieces c-band lnb on my 8ft mesh dish.
To my best ranking for gain:
1. avcomm+esx241(modifeid)
2.avcomm+zinwell zcf-d21b
3.avcomm+PSI (modified)
4.avcomm+bsc421
5.avcomm+titanuim

 

[moonbase]

... Like this you mean, ideally you don't want to be using the adjustable scalar for attaching the dish feed arms on to. Adapt another scalar ring to do that..that will sit behind the front adjustable one...

I can either use a second scalar as the fixing point to the dish feed support arms or I can use the Precision fixing head that attaches to the feed support arms then insert the AV-COMM barrel/Zinwell/Flat Scalar into this. I have attached a picture of the Precision feed support arm fixing head unit.

Rgds

 

[scopus]

Here are some pictures of mine...Oh Behave....I used a blue cap off another LNB as this fits the barrel alot better...

 

[moonbase]

Here are some pictures of mine...

You were quick out of the starting stalls in getting that up and running. I have got the horn and the KY, all I need now is the time to get it setup and begin testing.


Rgds