On 10/17/2011 02:28 AM, Mark Sims wrote:
Yes, at one time there was some very precision surveying antennas that were temperature
controlled. I'm not sure if they were just controlling just the preamp or the whole
antenna, but I got the impression that they were controlling the temperature
On 16 Oct, 2011, at 11:21 , WarrenS wrote:
> Does anyone ever add a temperature controller on the antenna? Maybe that
> should be my next test.
I've seen commercial temperature-controlled antennas. Here's one:
http://adriang.com/AACE-Industries/products.htm
Dennis Ferguson
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inal Message -
From: "Mark Sims"
To:
Sent: Sunday, October 16, 2011 5:28 PM
Subject: [time-nuts] Cable delay correction for Tbolt Cs substitude
Yes, at one time there was some very precision surveying antennas that were temperature controlled. I'm not sure if
they were
Yes, at one time there was some very precision surveying antennas that were
temperature controlled. I'm not sure if they were just controlling just the
preamp or the whole antenna, but I got the impression that they were
controlling the temperature everything inside the "radome" package.
A
Sounds like its time to do some testing and see what the effect is on the
actual hardware.
1) Heat and cool the Tbolt box and see if that effects THIS Phase delay,
maybe by way of its internal GPS amp/BPF.
In the past I have not seen a need to use LH's temperature controller on a
Tbolt that
Its merely a calculation of the change in inductance due to the
temperature induced change in skin depth due to the resistivity tempco
of the inner conductor wich varies the inductance per unit length.
Since RG6 uses a copper plated steel inner conductor there may be
significant differences in
Yes it reinitializes the filter, but that seems to NOT cause any problems.
I manually change the Tbolt's cable delay all the time using LH's "& C xx"
command to change/set the phase error on the fly while it is disciplining or
in the disable mode and I have not noticed any ill effects.
ws
**
I should have noted that the Haystack theoretical paper does indicate that SWR
could increase the tempco, so 50 vs. 75 ohm might have some effect -- but that
would be relative to the load (i.e., RX) end so if the Tbolt is designed for
75 ohm input (and its front end is actually optimized for re
I wouldn't think the cable type will make an order-of-magnitude difference.
Referenced in the Haystack note is another paper that goes through the
theoretical derivation that produced the "expected results" column. I think
it's the same URL but 067.pdf as the file name.
John
On Oct 16, 2011,
Thanks John
Any chance using 75 ohm cable (as suggested in the Tbolt manual) like RG6U,
when used in a 50 Ohm system could be orders of magnitude worse than
LMR-400?
Sounds like may be time to do some controlled cable experiments comparing
different cables.
I do know that Cheapie GPS timing
Using the cable delay message is probably not a good idea... it resets the
internal filters and state every time you change it.
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I did some very rough measurements last summer with. Run of LMR-400 that was
laying on the roof in the hot Georgia sun. Using a network analyzer to "ping"
the cable I found the day vs. night delay difference was pretty much in the
noise. I'll see if I can find the details and if so will post t
Anyone know what the propagation delay temperature coefficient is for RG6U coax
and how much it varies between different brands of cable?
In my efforts to improve the Tbolt's performance to make it into a better Cs
substitute,
test suggest that the temperature coefficient of the antenna lead-in
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