Ka B/C overlap (Hughes) Thread

[John]

....Patience is a virtue they say
Mine and Chris's are a different pcb layout as can be seen in the comparison pic between Llews & mine.
After quite a bit of fine tuning of divider resistor choices i can now make it switch ports with different lnb supply voltages.
A 2.7k was used instead of the 1.2k as shown on Llews drawing, the 22k one remained.
A lnb supply volts of 12v gave .691v onto pin 3 at 143mA current draw and gave RHC/V port. Analyser shows fairly flat gain across the band @ 56.7dBuV.
A lnb supply volts of 17v gave 1.04v onto pin 3 at 147mA current draw and gave LHC/H port. Analyser shows fairly flat gain across the band but with better gain @ 60.3dBuV.

All above findings were using a short 2mtr length of coax from the analysers voltage settings ...... i need to put on a length of test coax of about 18mtrs to simulate the actual installed length of coax to see if the slight voltage drop incurred effects the lnb polarity switching .
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[Vipersan]

10 out of 10 John ..
welcome to the club..

 

[Llew]

I see John, a different layout to mine and VS's I think. Glad it's switching OK with your R values.
12V switching is a bit near the reference voltage of 0.75 - only ~0.06V or so to go before it switches. Circuit hysteresis might cause unreliable switching.
Still, as long as the voltage levels remain OK when it's installed, should be fine.

 

[John]

I see John, a different layout to mine and VS's I think. Glad it's switching OK with your R values.
12V switching is a bit near the reference voltage of 0.75 - only ~0.06V or so to go before it switches. Circuit hysteresis might cause unreliable switching.
Still, as long as the voltage levels remain OK when it's installed, should be fine.

To be honest llew i had brain ache by this time ...... i knew i was getting close and was looking at a value between 1.2k t0 3.3k to get me in the ball park. I took a punt at a 2.7k and it did the switching. Due to starting to see double i decided to leave it at that and go and have a lie down in a darkened room lol.
Thanks again both for the pioneering work.

 

[Channel Hopper]

Have you checked the problem is not down to the phase cancellation of Ka band signals ?

https://www.satellites.co.uk/forums/attachments/jamming-with-spot-beams-ka-jpg.47034/

 

[Llew]

Due to starting to see double i decided to leave it at that and go and have a lie down in a darkened room lol.

Join the club. Had to come down twice today from my Gibby re-install for just such a break. A headache trying to align the heavy duty Gibertini polar mount.

 

[John]

I see John, a different layout to mine and VS's I think. Glad it's switching OK with your R values.
12V switching is a bit near the reference voltage of 0.75 - only ~0.06V or so to go before it switches. Circuit hysteresis might cause unreliable switching.
Still, as long as the voltage levels remain OK when it's installed, should be fine.

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Tried it on a 20mtr length of coax to establish the switching is still ok and all is fine.
Tidied up the mod, fitted the covers, re-test ok, re-seal and ready to go on the dish for a look around.

 

[scopus]

....Patience is a virtue they say
Mine and Chris's are a different pcb layout as can be seen in the comparison pic between Llews & mine.
After quite a bit of fine tuning of divider resistor choices i can now make it switch ports with different lnb supply voltages.
A 2.7k was used instead of the 1.2k as shown on Llews drawing, the 22k one remained.
A lnb supply volts of 12v gave .691v onto pin 3 at 143mA current draw and gave RHC/V port. Analyser shows fairly flat gain across the band @ 56.7dBuV.
A lnb supply volts of 17v gave 1.04v onto pin 3 at 147mA current draw and gave LHC/H port. Analyser shows fairly flat gain across the band but with better gain @ 60.3dBuV.

All above findings were using a short 2mtr length of coax from the analysers voltage settings ...... i need to put on a length of test coax of about 18mtrs to simulate the actual installed length of coax to see if the slight voltage drop incurred effects the lnb polarity switching .
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View attachment 95025 View attachment 95026 View attachment 95027

You have excelled yourself dear...give yourself a pat on the back, time to get my resistor value changed also....Very well done!

 

[John]

You have excelled yourself dear...give yourself a pat on the back, time to get my resistor value changed also....Very well done!

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Chars, ..... pure luck chap, i'm only a sparkie when all said and done.
The Masters did the donkey work bless 'em.

 

[Archive-8]

....Patience is a virtue they say
Mine and Chris's are a different pcb layout as can be seen in the comparison pic between Llews & mine.
After quite a bit of fine tuning of divider resistor choices i can now make it switch ports with different lnb supply voltages.
A 2.7k was used instead of the 1.2k as shown on Llews drawing, the 22k one remained.
A lnb supply volts of 12v gave .691v onto pin 3 at 143mA current draw and gave RHC/V port. Analyser shows fairly flat gain across the band @ 56.7dBuV.
A lnb supply volts of 17v gave 1.04v onto pin 3 at 147mA current draw and gave LHC/H port. Analyser shows fairly flat gain across the band but with better gain @ 60.3dBuV.

All above findings were using a short 2mtr length of coax from the analysers voltage settings ...... i need to put on a length of test coax of about 18mtrs to simulate the actual installed length of coax to see if the slight voltage drop incurred effects the lnb polarity switching .
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
View attachment 95025 View attachment 95026 View attachment 95027

Is this the ka/ku lnb?

 

[John]

Is this the ka/ku lnb?

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.... no , it's the Hughes Ka band B 19.7-20.2 lump Chris

 

[scopus]

It seems in my box of resistors, I only have a 2.2k, going to try that....

 

[John]

I see John, a different layout to mine and VS's I think. Glad it's switching OK with your R values.
12V switching is a bit near the reference voltage of 0.75 - only ~0.06V or so to go before it switches. Circuit hysteresis might cause unreliable switching.
Still, as long as the voltage levels remain OK when it's installed, should be fine.

.........................................................................................................................................................................
>>12V switching is a bit near the reference voltage of 0.75 - only ~0.06V or so to go before it switches.<<

I can see this happening now Llew, ..... I used my Televes analyser for setting up which gave 12v / 17v output for V-H, a better and more reliable way of setting up the divider will be to use the actual receiver thats going to be used for the job coupled with the same amount of coax run length used in the actual installation.
My designated rx for this band is a TM-5402 HD M3, it's lnb H/V output voltage is 19volts & 14.3volts at the end of a 20mtr run of coax, about 2 volts higher than the initial testing values of the Televes meter.
A final micro tweek needed.

 

[John]

It seems in my box of resistors, I only have a 2.2k, going to try that....

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... just hold off a bit Chris, can you measure your H/V lnb volts at your dish end on the coax that will be used to connect to the Hughes for me.

 

[scopus]

..........................................................................................................................................................................................................................
... just hold off a bit Chris, can you measure your H/V lnb volts at your dish end on the coax that will be used to connect to the Hughes for me.

12.72v for V and 17.43v for H dear....

 

[scopus]

12.72v for V and 17.43v for H dear....

That's off the the 5402 M3 BTW..

 

[Vipersan]

Please do keep in mind guys ..that 99% of what you will find with this lnb are data feeds ...thus is best used really with a TBS card or similar rather than a receiver stb .
rgds
VS

 

[Vipersan]

Just wanted to make you aware that you can get more accurate switching voltage generation by selecting fixed value of roughly 10:1
1.5k to ground and 22k to supply ...but inseting a mini pre-set into the mix ..the wiper of which will then provide a more accurate switch voltage for the comparator ...when set ..
I would suggest a 1k preset for this though 500 ohm or 2.2 k might also be tried ..
rgds
VS


For even greater accuracy ajustment ...use a multi turn preset..

5 Pack - 3296 Multi-turn Potentiometers (Variable Resistors/Preset/Trimmer/Pot)

 

[John]

Please do keep in mind guys ..that 99% of what you will find with this lnb are data feeds ...thus is best used really with a TBS card or similar rather than a receiver stb .
rgds
VS

Just wanted to make you aware that you can get more accurate switching voltage generation by selecting fixed value of roughly 10:1
1.5k to ground and 22k to supply ...but inseting a mini pre-set into the mix ..the wiper of which will then provide a more accurate switch voltage for the comparator ...when set ..
I would suggest a 1k preset for this though 500 ohm or 2.2 k might also be tried ..
rgds
VS
View attachment 95059

For even greater accuracy ajustment ...use a multi turn preset..

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Thanks VS, 22k / 1.5K is the value i'm now running to get me reliable switching using this TM-5402 Mk3 with it's fairly high H/V lnb voltage outputs + the 20mtr coax run before it hits the lnb at the dish position.
This gave me 0.59v on pin3 for V, 0.79v on pin 3 for H.
I'm now going to hook the 20mtr coax up to the 6983 sat card which has a lower lnb H/V output and also a different TM-5402 Mk 3 to see if it still switches ok.

 

[Archive-8]

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.... no , it's the Hughes Ka band B 19.7-20.2 lump Chris

View attachment 95054

Thanks :-) now I follow, (I have one of them in the back of the shed) never used. Good luck to you guys :-)