Just Sharing This AV-Comm Polariser + Zinwell lnbf

[WHATAGOAL1]

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

 

[moonbase]

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

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]

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.

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.

 

[John]

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

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 ?.

 

[moonbase]

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

.


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

Rgds

 

[s-band]

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 ?.

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.

 

[John]

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

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 ?.

 

[s-band]

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 ?.

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.

 

[Manikm909]

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....

wish i could use the zinwell - damn 5G interference here!