Useful video for LNB and masers...

[Steve Olney]

Hi All,

Don't know if this has been linked before - but I found this video from N1BUG very interesting.  I think it would be useful for those thinking about using LNBFs for Methanol and Water masers.

It's titled "Receiving 10 GHz EME with a small dish and LNB" but there's a fair bit of information which might be carried over to radio astronomy.

https://youtu.be/Beurcep8Tj0

I hope this is of interest.

Cheers

Steve Olney (HawkRAO)

[Marcus D. Leech]

Thanks.  I wasn't aware of that "BullsEye" LNBF.

Something that folks may not know about these LNBFs for Methanol is that you'll have to shift them up to
  the "high band" for 12.178GHz reception--by injecting 22kHz along with your DC power.  The chips they
  use (made by Phillips as I recall) have the tone-shift built-in and it's not exposed on an external pin.

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[Steve Olney]

The other thing to be aware of is that the high-band LO is 10.6 GHz - meaning 12.178 GHz comes out at 1578 MHz - which might cause the garden-variety RTL-SDRs to wheeze.

I've ordered a couple LNBFs with LO = 10.75 GHz - which means 12.178 GHz comes out at 1428 MHz - not so challenging for the garden-variety RTL-SDRs.

They're PLL units - but still +/-300 KHz spec.  Not impressive - but a lot better than DRO I suppose.  Not universals - so LO switching - just V/H switching via power supply voltage.

Interesting about the comment about V versus H polarisation noise figure - I wonder whether that's a general effect.  Might have something to do with the position of the respective probes in the waveguide ?

[Steve]

Rather "Not universals - so NO LO switching - just V/H switching"

On 22/03/2023 4:38 pm, Steve Olney wrote:
> Not universals - so LO switching - just V/H switching

--

Cheers

Steve Olney (HawkRAO)

(https://sites.google.com/view/hawkrao)

[Marcus D. Leech]

On 22/03/2023 01:38, Steve Olney wrote:
> The other thing to be aware of is that the high-band LO is 10.6 GHz -
> meaning 12.178 GHz comes out at 1578 MHz - which might cause the
> garden-variety RTL-SDRs to wheeze.
>
> I've ordered a couple LNBFs with LO = 10.75 GHz - which means 12.178
> GHz comes out at 1428 MHz - not so challenging for the garden-variety
> RTL-SDRs.
> They're PLL units - but still +/-300 KHz spec.  Not impressive - but a
> lot better than DRO I suppose.  Not universals - so LO switching -
> just V/H switching via power supply voltage.

Do you have a link to those LNBFs?   The only PLL ones I've ever found
require LO switching.  Not a HUGE deal I guess, but
  having a PLL one with a fixed high-band LO would be convenient...

Also, most of these LNBFs use Teflon-based circuit boards, so the traces
feeding the xtals/TCXOs will lift at the slightest
  whiff of provocation.  Just to gives folks a "heads up".

[Steve Olney]

Hi Marcus,

Haven't received them yet - so quality unknown here - caveat emptor...

Look for...

GEOSATpro SL1PLL

They're a funny shape...

BTW - the moulded-in IF range upper frequency on the back is wrong (I hope!!!)