Knucker not Receiving

[G6MNJ]

Built a Knucker over the past week for use with Portsdown 4.

Set first voltage regulator set to 5v output but I am concerned PCB has +4v on it - which is it?

All other volts are as expected 1.1 3.3 and 3.3v

The low esr 407uF caps are as requested. Checked all components installed ok.

The display screen shows the receiver is scanning but despite a large local DVBT signal it seems deaf to it.

Is there a setup/check routine anywhere I can run through please?

73 Paul G6MNJ

[g0mjw]

Hi Paul

The switcher should be set as low as you can get away with and the regulators still regulate. 4V is a good target. Any more means more heat dissipated.

When you say strong local signal, how are you generating it? From the Portsdown Lime, the Pluto ?

Mike

[G6MNJ]

Output is from a Pluto then through amps to around 10W into antenna

I will drop the volts to 4v then

Paul

[g0mjw]

If it is 10W you might be over-driving the RX. I suppose you don't know at this point if the TX signal is invalid or if the RX isn't working or both. I would check the spectrum is what you expect first and if it looks OK try with something relatively wide first, e.g. 500kHz with QPSK and 1/2 FEC. Also take out the PA and connect the Pluto to the RX via a suitably large attenuator, e.g. 60 dB or so.

Mike

PS - and make sure you use the correct input

[G6MNJ]

OK +10dB from PLuto through 50dB attenuator to lower socket of Knucker

I now get

Signal locked
437.000 Mhz 500kHz
Const QPSK FFT 2k
Guard 1/32
SSI 100
SQI 0
SNR 0.00
Per 0.02

[G6MNJ]

correction sqi 29

[g0mjw]

That's better. Drop the Pluto power another 10 dB?

[G6MNJ]

what do these numbers mean?

SSI signal strength Indicator
SQI signal quality Indicator
I know snr
but per?

I have now have received a signal, but the tuner seems extremely deaf to me with an antenna floating above the board with -5dB rx report SNR 0.5!

[G8GKQ]

It's all the the CQ-TV article. CQ-TV 271, page 16.

Dave

[radiogareth]

Generally anything BUT deaf, as the are designed for direct connection to a terrestrial antenna rather than a LNB with its vast excess of gain.
Slow to lock compared to DVBS/S2 yes, but it gets there.
Good luck.
Gareth