18v for LNB

The place for discussion about the 4-channel WinterHill DATV Receiver
G0DDX
Posts: 14
Joined: Tue Oct 10, 2017 8:38 am

18v for LNB

Post by G0DDX » Wed May 12, 2021 11:13 pm

I'm nearly there with my Winterhill. Just got to finish the lnb boards.

Now my question is:
Is there an 18V onboard voltage generated, and if so, how do you switch it in? OR... do I have to feed the whole thing with 18V similar to the Minitiouner?

I don't want to wreck it having got this far!

Geoff
G0DDX
De Geoff
G0DDX

G4EWJ
Posts: 1358
Joined: Wed Feb 17, 2010 10:11 am

Re: 18v for LNB

Post by G4EWJ » Thu May 13, 2021 1:56 am

Hi Geoff,

Definitely don't supply it with 18v. 15v is the maximum. 12v-15v is fine.

The LNB boards have an RT5047 chip, which is effectively a switched mode regulator. It can be set to to 0v, 13v or 18v output. It can also put a 22kHz 'tone' on the output voltage, to change the local oscillator in the LNB (not needed for QO-100).

Both LNB boards are controlled by PIC_A, which is in turn controlled by the Raspberry Pi. The receive commands sent to the Raspberry Pi by QuickTune and the Receive Commander (whpcrxcom) can be configured to send the required voltage setting.

There are also commands in the winterhill.ini file to turn on voltage generator X, so that the beacon will be received at startup on RX1 and RX3 to do the auto frequency calibration. The voltage generators are disabled at startup by default, so you will need to edit winterhill.ini to turn on voltage generator X when WinterHill starts.

The usual four receiver QO-100 configuration is to feed voltage generator X out of NIM_A TOP by setting the LNB jumper matrix accordingly. NIM_A TOP and NIM_B top are connected to the LNB via a splitter.

Brian

g0mjw
Posts: 2325
Joined: Sat Sep 20, 2014 9:15 am

Re: 18v for LNB

Post by g0mjw » Thu May 13, 2021 8:40 am

G0DDX wrote:
Wed May 12, 2021 11:13 pm
I'm nearly there with my Winterhill. Just got to finish the lnb boards.

Now my question is:
Is there an 18V onboard voltage generated, and if so, how do you switch it in? OR... do I have to feed the whole thing with 18V similar to the Minitiouner?

I don't want to wreck it having got this far!

Geoff
G0DDX
You don't need the LNB boards at all. Don't let that hold you up. They are optional extras. You can wire 12V directly to an LNB if you need to and rotate it for the correct polarisation if that is required. Max 200mW or say goodbye to the RF choke inside the NIM

The 12/18V is generated by a switching supply on the board. That is actually what the board is, a controllable LNB supply. It is switched on and off with the software control.

Never put 18V into the Winterhill.

Mike

g0mjw
Posts: 2325
Joined: Sat Sep 20, 2014 9:15 am

Re: 18v for LNB

Post by g0mjw » Thu May 13, 2021 9:04 am

G4EWJ wrote:
Thu May 13, 2021 1:56 am
Hi Geoff,

Definitely don't supply it with 18v. 15v is the maximum. 12v-15v is fine.
Yes and just to note it will run off a bit less than 12v. The intent was to use a standard shack 13.8V supply.

The first regulator is not there for regulation, it is there for protection. It is a low drop out linear regulator that prevents more than 12V getting to the following switching regulators. It is there for exactly the purpose of avoiding damage if people accidentally (or deliberately) supply the winterhill from too high a voltage. Starting a car with the gear still connected is a good example of the sort of unexpected catastrophe we hoped to avoid. So was the concept of putting in 18V to supply an LNB or using one of those unregulated plugin "Wall Wart" PSUs. The regulator is a better solution than a Zener diode used as a fuse blowing smoke generator. The limit on input voltage now becomes that of the regulator and how much power it can dissipate. The brave ham who never makes a mistake can bypass the protection.

The three switching supplies have a maximum input of 14V and a minimum of 2V above the output, so in this case work from around 7V as the PI requires 5V.

In practice this means if you supply more than that it will work. If you are using the LM317 which is in the current limiting configuration to power the LNB, it drops 1.2V so its output will be the input minus 1.2V, so not ideal as most LNBs seem to need 9V or more. The LNB supply boards should still be able to generate 12V and 18V. This means when out portable you can power it off a lead acid 12V battery, even if it drops below 12V. It might not start the car afterwards though if that's a requirement.

Mike

G7JTT
Posts: 338
Joined: Fri Jun 10, 2016 5:05 pm

Re: 18v for LNB

Post by G7JTT » Thu May 13, 2021 10:31 am

I use one of these to get my 12/18v from a 5v supply via a bias T so I can't damage the NIM.

https://www.ebay.co.uk/itm/193540864083

I have it wired up for 12v then switch in a 11k resistor to give me the 18v. The switching is just a 3 way switch off-12v-18v.

73 John G7JTT

G0DDX
Posts: 14
Joined: Tue Oct 10, 2017 8:38 am

Re: 18v for LNB

Post by G0DDX » Thu May 13, 2021 3:00 pm

Sorry for the Dumb question! I always say its better to look dumb by asking daft Q's, than to have to put up with the delay, embarrassment, and hand in the pocket for your wallet because you didn't ask a daft question.

All is well, and I can only say thanks to everyone for the answers. Its pointed me in the right direction.

Hope to get narrowband with WB rx running in the next couple of weeks, then start on the WB PA which is a daunting task for me.
My timing will depend on the other job in hand and that's a new hitch, suspension, and converting the trailer to take a scam12.
Need that done by Field Day, about 5 weeks time.

Again thanks..

Geoff
G0DDX
De Geoff
G0DDX

G1BVI
Posts: 282
Joined: Wed Aug 02, 2017 7:32 am

Re: 18v for LNB

Post by G1BVI » Sun Jan 02, 2022 7:30 pm

Over the Xmas break I finished my Winter Hill.
Only problem is I cannot get 18V out of the NIMS?

I have built two cards for the X and Y Generators but neither seem to be enabled .
The boards are both getting a supply but the enable pin is 0V.

Struggling to find where this comes from on the schematic.

The LNB Voltage being output from both boards is 5V.

When !2v is selected this is present on the NIM

What have I overlooked?
Hope someone can advise

Thanks in advance

73 and a Happy 2022

Nick G1BVI
Attachments
20220102_192245 (1).jpg
20220102_192245 (1).jpg (1018.48 KiB) Viewed 4525 times
20220102_183706 (1).jpg
20220102_183706 (1).jpg (571.34 KiB) Viewed 4525 times
20220102_182944 (1).jpg
20220102_182944 (1).jpg (1.44 MiB) Viewed 4525 times

G4EWJ
Posts: 1358
Joined: Wed Feb 17, 2010 10:11 am

Re: 18v for LNB

Post by G4EWJ » Sun Jan 02, 2022 9:03 pm

Hi Nick,

The LNB boards are controlled by the tuning commands that come from QO-100 QuickTune, or whpcrxcom, the PC program for sending tuning commands for any frequency.

When you enter the receiver parameters in QT, set the voltage for each receiver according to how your LNB is orientated. Normally, 18v would be used to select horizontal polarisation for QO-100.

It is also possible to set the LNB boards in the winterhill.ini file. You don't have to set them here and you still need to put the correct voltage in QT, but setting the LNB boards in winterhill.ini will allow WH to automatically calibrate the receiver frequencies using the QO-100 beacon.

Below is an extract from winterhill.ini. To enable the LNB boards, put a # at the start of the first block of commands and remove the # from the second block of commands and then reboot.

Are you familiar with Linux? You can edit the file as follows:

cd /home/pi/winterhill
nano winterhill.ini
DO THE CHANGES
CTRL-X then Y then ENTER to save
sudo reboot

You will need to use the whpcrxcom program (on the Wiki) to control the second LNB board, rather than QT.

Brian


COMMAND = [to@wh],rcv=1,freq=10491500,offset=9750000,srate=1500,fplug=A
COMMAND = [to@wh],rcv=3,freq=10491500,offset=9750000,srate=1500,fplug=A
COMMAND = 3 # a single digit causes a delay of that many seconds
COMMAND = [to@wh],rcv=2,freq=10499250,offset=9750000,srate=333,fplug=A
COMMAND = [to@wh],rcv=4,freq=10498750,offset=9750000,srate=333,fplug=A

#COMMAND = [to@wh],rcv=1,freq=10491500,offset=9750000,srate=1500,fplug=A,vgx=hi
#COMMAND = [to@wh],rcv=3,freq=10491500,offset=9750000,srate=1500,fplug=A,vgx=hi
#COMMAND = 3 # a single digit causes a delay of that many seconds
#COMMAND = [to@wh],rcv=2,freq=10499250,offset=9750000,srate=333,fplug=A,vgx=hi
#COMMAND = [to@wh],rcv=4,freq=10498750,offset=9750000,srate=333,fplug=A,vgx=hi

G1BVI
Posts: 282
Joined: Wed Aug 02, 2017 7:32 am

Re: 18v for LNB

Post by G1BVI » Sun Jan 02, 2022 10:26 pm

Hi Brian
That makes sense'
I am going to have to change the ini file anyway as I have a non standard offset on my LNB to bring it out on 70cm.

I tried it and I get about 8 volts now.

The Inductor is also getting hot
I just noticed too that I have fitted R4 and R5 pull up resistors on my boards
It looks like there has been an update as these are fitted on the main board.

What voltage should I expect on the enable and select lines?

Thanks again

73

Nick

G4EWJ
Posts: 1358
Joined: Wed Feb 17, 2010 10:11 am

Re: 18v for LNB

Post by G4EWJ » Mon Jan 03, 2022 12:38 pm

8v doesn't sound right. Is that the open circuit voltage?

R4 and R5 SHOULD be fitted on the LNB psu boards. These pull down resistors stop the enable and select lines floating when the PICs are reset.

Both LNB psu boards are controlled by PIC_A. ENABLE goes high to activate the LNB psu board and SELECT is low for 13v and high for 18v. Those signals should be at 3.3v levels.

Brian

Post Reply

Return to “The WinterHill DATV Receiver”