Re: [time-nuts] OT loosing things
Rick,
On 11/15/2010 06:25 AM, Richard (Rick) Karlquist wrote:
Someone was asking about SC cut crystals to play with.
I have a few dozen 10.23 MHz SC cut crystals that are
interchangeable with 10811 10 MHz crystals, except for
the frequency difference. They were made for a GPS
version of the 10811 that never saw the light of day.
Any interest in these?
Vigorous hand-waving. Yes.
Cheers,
Magnus
10 MHz locked LNBs do not use a separate connector. Everything goes down/up
the single main coax. The typical L-band down-converted frequency and the 10
MHz are easily separated, as is the DC. These are definitely not
inexpensive. Regards - Mike
Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-901-9193 cell
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of jimlux
Sent: Sunday, November 14, 2010 11:49 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] ADEV
David I. Emery wrote:
3. External reference LNBs with 10 MHz (pretty universal) going
up the cable that also carries power and brings the L band signal down.
I'm not entirely sure how many of these designs simply bandpass filter
and then limit the 10 MHz and use that directly as a PLL reference and
how many phase lock a VCXO to the 10 MHz coming in. Otherwise similar
(and often derived from designs for) the internal reference PLL types
in 2 above.
And, I'll bet those are fairly pricey.. (after all, it needs another
connector, and that's a price sensitive application..)
Someone was asking about SC cut crystals to play with.
I have a few dozen 10.23 MHz SC cut crystals that are
interchangeable with 10811 10 MHz crystals, except for
the frequency difference. They were made for a GPS
version of the 10811 that never saw the light of day.
Any interest in these?
Absolutely!
JDB.
[still working on that DIY GPSDO design]
LART. 250 MIPS under one Watt. Free hardware design files.
http://www.lartmaker.nl/
At 11:25 PM 11/14/2010, Richard (Rick) Karlquist wrote:
Someone was asking about SC cut crystals to play with.
I have a few dozen 10.23 MHz SC cut crystals that are
interchangeable with 10811 10 MHz crystals, except for
the frequency difference. They were made for a GPS
version of the 10811 that never saw the light of day.
Any interest in these?
Yep.
Rex wrote:
On 11/14/2010 7:24 PM, David I. Emery wrote:
-
External reference LNBs with 10 MHz (pretty universal) going
up the cable that also carries power and brings the L band signal down.
I'm not entirely sure how many of these designs simply bandpass filter
and then limit the 10 MHz and use that directly as a PLL reference and
how many phase lock a VCXO to the 10 MHz coming in. Otherwise similar
(and often derived from designs for) the internal reference PLL types
in 2 above.These ER types are more apt to be used for more exotic
specialized applications where very high frequency accuracy or some
degree of phase coherence with other equipment or LNBs is useful.Obviously with the high multiplication factor, one needs a quiet
reference inside the PLL bandwidth (and that is pretty wide to ensure
reliable lock) - one suspects that issues with degradation due to
mechanically induced noise and phase shift in the cables can be a
problem.
I picked up an LNB a about 10 years back that used this external
reference method. The LO in the thing was a DRO that locked to a 10 MHz
signal coming up the cable. The LO in this one locked to 10.750 GHz.
Experimenting, I found that the DRO adjustment screw could be turned and
it would lock every 10 MHz. I found it would lock as low as 10.690. I
assume it would tune up about that far too.
I needed an LO in the 10 GHz area, so I hacked mine to use it just as a
LO, not using any of the receive chain. Here's a page where I described
the LNB and what I did with it.
http://www.xertech.net/Projects/sat_lo.html
Maybe the description there will help someone. If nothing else, it show
pictures of what one external ref type LNB looks like.
Interesting.. NORSAT makes lots of those sort of devices for VSAT (Very
Small Aperture Terminal) applications (e.g. satellite internet).. I've
seen a few of them at work being used in that kind of application.
Those would make life easier for my scheme.
They're not quite so common as the LNB for Ku-band TV (at least I've not
seen them at Best Buy/Radio Shack kinds of places), nor have I seen them
on neighbors houses or out at the curb on trash day.
But I'm starting to think the pilot tone technique might be easier... At
first glance, if one considers two alternatives:
LO locked to reference, down converting RF to baseband and digitizing
and
LO not locked, but with in-band pilot tone, down converting RF to
baseband and digitizing, then essentially mixing with the downconverted
pilot tone
should produce comparable results. In the first, you're controlling the
LO (at least inside the loop bandwidth), and in the second, you're
really measuring it, then taking out its changes.
Assuming that the pilot tone amplitude is small enough that it doesn't
cause nonlinearity problems in the LNB, and that it's in band, it should
be comparable.
But, maybe there's a SNR of the reference issue? In a PLL, you're
comparing a very strong signal to a very strong reference, so the noise
floor of both is very small, while in the pilot tone, the "reference" is
strong, but not as strong, relative to the noise flor.
Mike Feher wrote:
10 MHz locked LNBs do not use a separate connector. Everything goes down/up
the single main coax. The typical L-band down-converted frequency and the 10
MHz are easily separated, as is the DC. These are definitely not
inexpensive. Regards - Mike
Ah.. but the question is really not whether the "new" price is cheap,
but whether there's some reason why someone would be doing a massive
refit, and dumping lots of these on the market surplus.
Well, that I do not know. The majority of Ku & Ka LNBs for home TV use are
using free running DRO's. I have a bunch of them, and never ran across any
locked ones, except for some of the ones used for internet service. My real
experience is what we use in military satcom terminals at Ku and Ka bands,
with apertures from 0.6 to 9.2 meters, and they are all locked to an
external 10 MHz reference. I doubt if you will see any major dumping of
those. Especially now, because of strict ITAR. Even if one can buy it
directly from the manufacturer, once the military has owned it, they will
probably dispose of it in such a way that we will not see them on ebay.
Regards - Mike
Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-901-9193 cell
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of jimlux
Sent: Monday, November 15, 2010 9:21 AM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] ext ref LNB Re: ADEV
Mike Feher wrote:
10 MHz locked LNBs do not use a separate connector. Everything goes
down/up
the single main coax. The typical L-band down-converted frequency and the
10
MHz are easily separated, as is the DC. These are definitely not
inexpensive. Regards - Mike
Ah.. but the question is really not whether the "new" price is cheap,
but whether there's some reason why someone would be doing a massive
refit, and dumping lots of these on the market surplus.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Mike Feher wrote:
Well, that I do not know. The majority of Ku & Ka LNBs for home TV use are
using free running DRO's. I have a bunch of them, and never ran across any
locked ones, except for some of the ones used for internet service. My real
experience is what we use in military satcom terminals at Ku and Ka bands,
with apertures from 0.6 to 9.2 meters, and they are all locked to an
external 10 MHz reference. I doubt if you will see any major dumping of
those. Especially now, because of strict ITAR. Even if one can buy it
directly from the manufacturer, once the military has owned it, they will
probably dispose of it in such a way that we will not see them on ebay.
Regards - Mike
I doubt the LNB is export controlled.. It's unlikely to have an
exotically low noise temperature, they're not cryogenic, they don't use
components with dual-use, it's just part of a receiver. If you go to
the NORSAT website, for instance, they don't make much mention of export
controls (yeah, I'm sure the invoice/quote would have export
boilerplate on it "the contents of this have not been reviewed... use,
sale, distribution may require license...")
http://www.norsat.com/lnb/blog
And I note that the datasheet's pretty sketchy on the external reference
LNBs.. They give phase noise as follows (for Ku band, 10.75 GHz LO):
-75dBc/Hz @ 1kHz
-85 @ 10k
-95 @ 100k
But they don't say whether that's added to the reference noise, or
that's the "outside the loop" noise, or what..
What's interesting is that the Ka-band LNB (for 18-19 GHz, which is low
Ka, to my thinking.. I think 30 when I think Ka).. the noise is actually
lower
-65 @ 1k
-75 @ 10k
-95 @ 100k
-100 @ 1M
The military Ka band is 20.2 to 21.2 on receive and 30 to 31 on transmit.
Norsat of course has been making these for about 15 years, one of the first.
Back when I was working on Milstar 25 years ago, with the same receive
frequency, even the NF was classified. No, it does not make sense, but, that
was the way it was. I just had to deal with some ITAR related issues, where,
COTS equipment is being used, yet, it is now built for, or owned by the
military, and, while the hardware is not classified, it is restricted, even
as to who may work on it. I am just saying, do not hold your breath to see
them coming on the military surplus market. Regards- Mike
Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-901-9193 cell
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of jimlux
Sent: Monday, November 15, 2010 10:16 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] ext ref LNB Re: ADEV
Mike Feher wrote:
Well, that I do not know. The majority of Ku & Ka LNBs for home TV use are
using free running DRO's. I have a bunch of them, and never ran across any
locked ones, except for some of the ones used for internet service. My
real
experience is what we use in military satcom terminals at Ku and Ka bands,
with apertures from 0.6 to 9.2 meters, and they are all locked to an
external 10 MHz reference. I doubt if you will see any major dumping of
those. Especially now, because of strict ITAR. Even if one can buy it
directly from the manufacturer, once the military has owned it, they will
probably dispose of it in such a way that we will not see them on ebay.
Regards - Mike
I doubt the LNB is export controlled.. It's unlikely to have an
exotically low noise temperature, they're not cryogenic, they don't use
components with dual-use, it's just part of a receiver. If you go to
the NORSAT website, for instance, they don't make much mention of export
controls (yeah, I'm sure the invoice/quote would have export
boilerplate on it "the contents of this have not been reviewed... use,
sale, distribution may require license...")
http://www.norsat.com/lnb/blog
And I note that the datasheet's pretty sketchy on the external reference
LNBs.. They give phase noise as follows (for Ku band, 10.75 GHz LO):
-75dBc/Hz @ 1kHz
-85 @ 10k
-95 @ 100k
But they don't say whether that's added to the reference noise, or
that's the "outside the loop" noise, or what..
What's interesting is that the Ka-band LNB (for 18-19 GHz, which is low
Ka, to my thinking.. I think 30 when I think Ka).. the noise is actually
lower
-65 @ 1k
-75 @ 10k
-95 @ 100k
-100 @ 1M
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
On Mon, Nov 15, 2010 at 06:20:55AM -0800, jimlux wrote:
Mike Feher wrote:
10 MHz locked LNBs do not use a separate connector. Everything goes down/up
the single main coax. The typical L-band down-converted frequency and the
10
MHz are easily separated, as is the DC. These are definitely not
inexpensive. Regards - Mike
Ah.. but the question is really not whether the "new" price is cheap,
but whether there's some reason why someone would be doing a massive
refit, and dumping lots of these on the market surplus.
FWIW, I have purchased C, US FSS Ku and Euro FSS Ku ER
LNBs on Ebay for well under $100 NOS in box with spec sheets.
Not yet seen Ka ones. Did buy an X band.
Sellers had a few (eg two or three), never seen large
quantities... but surplus ER LNBs command LOWER prices because of the need
for the external reference and so forth...
You would, naturally enough need a feedhorn (these are mostly
WR90 for Ku)...
Your pilot tone concept is interesting... I am not sure
how large your array might be and what issues would be involved
in distributing the pilot tone to it... nor exactly what the
noise spectrum (ADEV) of a cheapie DRO LNB might look like and
what would be required to generate the necessary LO phase estimates
from the pilot as translated by the unstable LO...
--
Dave Emery N1PRE/AE, die@dieconsulting.com DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."