Just Sharing This AV-Comm Polariser + Zinwell lnbf

strange yesterday, it was bitterly cold yesterday, but i went outside for 10 minutes and put zinwell on, no tuning, just swapped with c1, absentmindly i put the flat scaler on.
Surprised when I scanned the signal was just as good as with the conical on my offset dish
So hoping for a few extra transponders when it warms up and I can mess with it
 
WHATAGOAL1 said:
strange yesterday, it was bitterly cold yesterday, but i went outside for 10 minutes and put zinwell on, no tuning, just swapped with c1, absentmindly i put the flat scaler on.
Surprised when I scanned the signal was just as good as with the conical on my offset dish
So hoping for a few extra transponders when it warms up and I can mess with it
Click to expand...


I have found that fine tuning the position of a C Band LNB to be quite "fuzzy", the max signal is available over quite a few millimetres of focal length, much more range than Ku Band. Same for the position of the scalar on the LNB barrel. By comparison, the Ku Band signal drops away sharply once the LNB deviates from the sweet spot for focal length. As far as I am aware it is a characteristic of the wavelength, C Band is a lot more tolerant compared to Ku Band.

Rgds
 
s-band said:
When I was playing with the Fortec 2.4, I had no success with the Zinwell LNB and couldn't work out why. I ran a few noise figure & gain tests with the Zinwell compared against a Tit, Norsat & Chaparral. The NF was better than the Tit but not as good as the Norsat or Chaparral. However, there was something a bit strange that I put down to local interference. So the next step was to check the phase noise. Hardly needed, I could see the problem feet away. The LO appears to be injection locking an oscillation in the front end or vice versa. Curiously, the local oscillator can be stopped altogether with some input terminations. It does it on V & H.

The attached shows the IF output with a strong input signal and the 5150ish muck that comes out of the input guide. It's ******. Not surprising that no TV transponders would lock whilst I could still see something from the beacons.
Click to expand...

The new LNB arrived, thanks, John and to AV-comm. A quick check shows it's not unstable. It is still a bit frisky but only in the same way as Tits. The noise bandwidth is not much wider than the specified range so I'm not sure how much luck I will have using the duff one as a wide band LNA. It depends what is restricting it.
new_zinwell_1425_std.webp
 
s-band said:
The new LNB arrived, thanks, John and to AV-comm. A quick check shows it's not unstable. It is still a bit frisky but only in the same way as Tits. The noise bandwidth is not much wider than the specified range so I'm not sure how much luck I will have using the duff one as a wide band LNA. It depends what is restricting it.
View attachment 104669
Click to expand...


Glad that's turned up G, did you get tickled for a bit of import tax ??, hope not but they have us over a barrel don't they. (no pun intended)

Any chance of a side by side spec pic of the other duff unit to compare the two when you have a minute ?.
 
s-band said:
The new LNB arrived, thanks, John and to AV-comm. A quick check shows it's not unstable. It is still a bit frisky but only in the same way as Tits. The noise bandwidth is not much wider than the specified range so I'm not sure how much luck I will have using the duff one as a wide band LNA. It depends what is restricting it.
View attachment 104669
Click to expand...
.


Pleased that you got it sorted, they do seem to try to provide good customer service at AV-COMM

Rgds
 
John said:
Glad that's turned up G, did you get tickled for a bit of import tax ??, hope not but they have us over a barrel don't they. (no pun intended)

Any chance of a side by side spec pic of the other duff unit to compare the two when you have a minute ?.
Click to expand...
No tax, below limit and/or declared as returned goods
The good one has a piece of absorber on the 2nd stage. I tried adding some to the duff one, it didn't do much. The duff one has a low frequency oscillation which I don't have time or inclination to track down that's what stops it working for most things. The mixer/oscillator design is not very nice. Changes in match on the input alter the LO frequency and it is possible to stop the oscillator if a mis-match is presented to the input (sticking a finger up it in a critical position). This applies to good and bad. However, that doesn't stop it working under normal conditions.
The pics show the clean LO on the good one and the comb on the bad. The photo has the good one on the left.

z_good_std.webp z_duff_std.webp zinwell_good-bad_429_std.webp
 
s-band said:
No tax, below limit and/or declared as returned goods
The good one has a piece of absorber on the 2nd stage. I tried adding some to the duff one, it didn't do much. The duff one has a low frequency oscillation which I don't have time or inclination to track down that's what stops it working for most things. The mixer/oscillator design is not very nice. Changes in match on the input alter the LO frequency and it is possible to stop the oscillator if a mis-match is presented to the input (sticking a finger up it in a critical position). This applies to good and bad. However, that doesn't stop it working under normal conditions.
The pics show the clean LO on the good one and the comb on the bad. The photo has the good one on the left.

View attachment 104671 View attachment 104670 View attachment 104672
Click to expand...


Hmm, see what you mean. Just digressing ....... ordered/paid for that 8000RI on the 8th and according to tracking it's already at Heathrow, can't be right-can it ?.
 
John said:
Hmm, see what you mean. Just digressing ....... ordered/paid for that 8000RI on the 8th and according to tracking it's already at Heathrow, can't be right-can it ?.
Click to expand...
I had a go using it as an LNA. Only looking at gain it was within 3dB 3.4-3.9, dropping by 10dB at 4.2 and by 18dB at 4.8. Could be the way I coupled in to it but I think it's real. That doesn't take into account noise performance and it may be fine over the normal band even with that droop in gain if the noise is good. The probes may be the problem at 4.8. I'm not going to spend any more time on it now. I may try it again when I get the tin dish out again.
Next day to UK airport is believable. My ADL got from Aus to UK in 2 days then spent 5 days in customs, over a weekend, then another couple to pay and get here.
 
Captain Jack said:
This AV Comm + Zinwell LNB combination is impressive. I have removed the LNB rotator for now and stuck the C band LNB on top of the Ku, so essentially it's not at focus (using my declination jack for adjustment). Even so, I am getting some very impressive signals even on a crappy, cloudy day across the board. BBC Africa on 1W is pushing over 9dB and AFN TP is 7.7dB (F15 readings).

This is without any sort of fine tuning - just stuck the LNB into the barrel and barrel on the dish...

View attachment 98288

One thing that's annoying is that the LNB cover is costing me around 0.5dB, which is a lot considering how every tenth of a dB counts here. Any suggestions on a more "transparent" cover? Apart from cling film....

View attachment 98289

Now just need that skew control....
Click to expand...
wish i could use the zinwell - damn 5G interference here!
 
Does the LNB receive circular polarization without a Dielectric Plate?
I need something alternative for the dielectric plate
 
hazem909 said:
Does the LNB receive circular polarization without a Dielectric Plate?
I need something alternative for the dielectric plate
Click to expand...

>Does the LNB receive circular polarization without a Dielectric Plate? < , - Short answer Yes, but it will be 'seeing' both L & R polarities at the same time and at reduced levels and, short answer again, is not ideal.
>I need something alternative for the dielectric plate < , - Short answer again, there are alternative options other than the simple 'plate' but you are entering into the world of 'modifying / fabrication' of the Cband lnb system to some degree - if done correctly there is some improvement to be had over the simple 'plate' .
There are a few examples of modifications to be found on the forum by a few forum members over the years , ..... a certain amount of fabrication skill is usually required though.
 
hazem909 said:
Does the LNB receive circular polarization without a Dielectric Plate?
I need something alternative for the dielectric plate
Click to expand...
A dielectric plate is not the only fix to receive circular signals, as the waves can be depolarised with both mechanical and electronic means. Many nposts on this forum so go search.

Which frequencies are of interest to you ?
 
I have a problem with the angle adjustment of the dielectric plate, which prevents me from receiving frequencies/Feeds on Eutelsat 10E. There's a protrusion of the plate outside the LNB nozzle, preventing me from covering it.

As a result, it's affected by humidity and rain. Therefore, I'm looking for an electronic solution, not a manual one.
 
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