Safely getting the electrical length of a connected antenna feedline
Hi:
Another option is so Google for a "Breakout board" for the IC you're looking to work with. People like Spark Fun, Seed
studio, &Etc make these.
It's a board that holds the chip and the needed accessory parts, but needs something else like an Arduino.
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.
-------- Original Message --------
On Tue, Aug 9, 2016 at 9:10 AM, Bob Albert via time-nuts
time-nuts@febo.com wrote:
Yes, a board with the required footprint would be the way to go. Where does one find that?
You can have small PCBs made for $3 each.
There are places here in the US that will do PCBs for $3/square inch
with a one square inch minimum. basicpcb.com sone of these.
It is not hard to design a basic "carrier board" that has just one
chip's footprint and maybe a decoupling capacitor and a 0.1" header
connector. Many times the chip's data sheet will have an example PCB
layout you can borrow that will fit in a one square inch board.
These are a little larger than what I was thinking of but were
mentioned the other day in funwithtubes@yahoogroups.com and are
probable more suitable for most projects anyway:
http://qrpme.com/?p=product&id=MEP
On Tue, 9 Aug 2016 16:10:38 +0000 (UTC), you wrote:
Yes, a board with the required footprint would be the way to go. Where does one find that?
On Tuesday, August 9, 2016 12:00 AM, David <davidwhess@gmail.com> wrote:
Richard mentioned the SMD to leaded adapters which work well.
Another way which is more suitable for Manhattan or dead bug type
construction is to glue or solder down just tiny printed circuit board
which has the SMD footprint and then solder directly to the leads or
extensions to the pads. This does not increase the lead length any
more than necessary and places the ground plane in close proximity for
best RF performance. If you are desperate, you can cut an SMD
footprint out of an existing unused donor board.
On Tue, 9 Aug 2016 03:37:07 +0000 (UTC), you wrote:
Your comments on layout made me think again of how to implement these projects. How do you use a 14 pin SMD IC? I could try to connect it with flying leads but I'd like something better. Is there some kind of socket for these devices? Or a generic board to receive such things?
You left out the obvious time-nut solution: Calibrate and characterize an
ensemble of HP5071A's to correct absolute time at NIST. Transport the
ensemble (correcting, if necessary, for general relativisitic effects) to
your house. Set the cable delay in your GPS receiver to zero. The delta
between your receiver PPS and the HP5071A Ensemble is the time delay in
your cable and GPS Antenna - AFTER you account for the time delta between
USNO and NIST time (available at
http://www.nist.gov/pml/div688/grp50/nistusno.cfm )
Tim N3QE
On Mon, Aug 8, 2016 at 2:18 PM, Bob Stewart bob@evoria.net wrote:
Earlier this year, with some help, I pulled the dish off of an old DishTV
antenna on the roof and put a 5V bullet antenna on the mast. I also pulled
a new cable through by attaching it to the old one. The problem is that I
was not able to measure the new cable. So, the question is, without going
back on the roof in this heat, how can I measure the electrical length of
the line I pulled?
I was thinking of using my 8640B signal generator and sending some RF back
up the line to get a quarter wavelength at the null. But that assumes a
lot, including that the other end is open at 3MHz, or whatever the
frequency works out to be, as well as that the high voltage on the antenna
end won't be high enough to blow the LNA.
So, how much RF I can safely send up the line? I've got an 8558B spectrum
analyzer, but it's not on the bench, and it would be easier to use my
scope, which sadly is a 70s vintage Tek 455. Do I put this all together
with a lead from the generator to a tee at the measuring device and tune
for a null? My experience at getting precise measurements on anything
longer than a few inches is effectively none, but I'd guess that I want
less than 0.5V at the LNA during this test. Oh, and I do have an 8444A
tracking generator that can output -10 dbm as well as a 10 db attenuator
within easy access. That could get a quick spot on the null point.
Most importantly, of course is the question of whether this will even
work.
Bob - AE6RV ------------------------------------------------------
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
Thanks David. I have ordered some from ebay, very cheap.
5pcs SO/SOP/SOIC/SSOP/TSSOP/MSOP14 to DIP 14 Adapter PCB Board Converter MA
| |
| | | | | | | |
| 5pcs SO/SOP/SOIC/SSOP/TSSOP/MSOP14 to DIP 14 Ad...US $1.32 New other (see details) in Business & Industrial, Electrical & Test Equipment, Electronic Components |
| |
| View on www.ebay.com | Preview by Yahoo |
| |
| |
On Wednesday, August 10, 2016 11:01 AM, David <davidwhess@gmail.com> wrote:
These are a little larger than what I was thinking of but were
mentioned the other day in funwithtubes@yahoogroups.com and are
probable more suitable for most projects anyway:
http://qrpme.com/?p=product&id=MEP
On Tue, 9 Aug 2016 16:10:38 +0000 (UTC), you wrote:
Yes, a board with the required footprint would be the way to go. Where does one find that?
On Tuesday, August 9, 2016 12:00 AM, David davidwhess@gmail.com wrote:
Richard mentioned the SMD to leaded adapters which work well.
Another way which is more suitable for Manhattan or dead bug type
construction is to glue or solder down just tiny printed circuit board
which has the SMD footprint and then solder directly to the leads or
extensions to the pads. This does not increase the lead length any
more than necessary and places the ground plane in close proximity for
best RF performance. If you are desperate, you can cut an SMD
footprint out of an existing unused donor board.
On Tue, 9 Aug 2016 03:37:07 +0000 (UTC), you wrote:
Your comments on layout made me think again of how to implement these projects. How do you use a 14 pin SMD IC? I could try to connect it with flying leads but I'd like something better. Is there some kind of socket for these devices? Or a generic board to receive such things?
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.
I concur. I have been using ExpressPCB extensively over the last 2 years
with great satisfaction now that it is possible to get Gerber files from
them.
I typically use the mini board pro service (3 bare boards, 2 sided with
solder mask and silk screen) for prototypes and then buy the Gerbers to
have production quantities done overseas.
The boards are of high quality and the service is very fast at a very
reasonable price.
The only gotcha with regard to Gerber files is that you can only buy
Gerbers for boards that you have actually bought from them, so the process
is to buy the prototypes, then if you are happy with those, buy the Gerbers
for that design.
Didier KO4BB
On Tue, Aug 9, 2016 at 3:06 PM, Brooke Clarke brooke@pacific.net wrote:
Hi:
I've had good luck using any of the the ExpressPCB services that include
solder mask with surface mount parts where the pitch is 0.05" (half normal
DIP) and hand soldering (requires stereo microscope).
http://www.prc68.com/I/BTSG.shtml (battery top signal generator)
http://www.prc68.com/I/Images/ICS525v1o.jpg
http://www.prc68.com/I/SMT.shtml http://www.prc68.com/I/SMT.shtml
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/m
ailman/listinfo/time-nuts
and follow the instructions there.
What are the important parameters regarding purchase of a stereo microscope? I see some on ebay for around $50; are those good?
Bob
On Thursday, August 11, 2016 10:00 AM, Didier Juges <shalimr9@gmail.com> wrote:
I concur. I have been using ExpressPCB extensively over the last 2 years
with great satisfaction now that it is possible to get Gerber files from
them.
I typically use the mini board pro service (3 bare boards, 2 sided with
solder mask and silk screen) for prototypes and then buy the Gerbers to
have production quantities done overseas.
The boards are of high quality and the service is very fast at a very
reasonable price.
The only gotcha with regard to Gerber files is that you can only buy
Gerbers for boards that you have actually bought from them, so the process
is to buy the prototypes, then if you are happy with those, buy the Gerbers
for that design.
Didier KO4BB
On Tue, Aug 9, 2016 at 3:06 PM, Brooke Clarke brooke@pacific.net wrote:
Hi:
I've had good luck using any of the the ExpressPCB services that include
solder mask with surface mount parts where the pitch is 0.05" (half normal
DIP) and hand soldering (requires stereo microscope).
http://www.prc68.com/I/BTSG.shtml (battery top signal generator)
http://www.prc68.com/I/Images/ICS525v1o.jpg
http://www.prc68.com/I/SMT.shtml http://www.prc68.com/I/SMT.shtml
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/m
ailman/listinfo/time-nuts
and follow the instructions there.
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.
I used the PPS from a Thunderbolt (fast rise lime, low rep frequency, was handy) and a digital storage scope and a couple of resistors to make a reflectometer based on this experiment:
www.ko4bb.com/getsimple/index.php?I'd=coax-cable-impedance-matching
You can very clearly see a 50 ohm/75 ohm mismatch.
The biggest variable will be the velocity factor.
Didier KO4BB
On August 8, 2016 2:18:02 PM CDT, Bob Albert via time-nuts time-nuts@febo.com wrote:
I host a group called something like HF Antennas. There I posted a
link to an article on how to measure coaxial cable. The easiest way is
with a spectrum analyzer and a tracking generator.
You connect the generator to the analyzer through a Tee that goes to
the unknown coax. You will see a group of peaks and nulls over the
spectrum. The spacing is a half wave of the cable. The match needs to
not be good to see the nulls best, and you will need to know the
propagation constant of the cable. Chances are, the match won't be
good over the entire range so you are okay with that. Propagation
constant of most coaxial cable runs around 66%.
You can also use a TDR setup but you'll have to make one, with a pulser
and a 'scope. I downloaded a circuit for a pulser that uses one IC. I
have the parts but haven't built it yet, as I am stalled by the problem
of connecting to a 14 pin SMD part. The IC uses one part as an
oscillator and the other 5 in parallel to drive 50 Ohms. Again, you
use a Tee and measure the time for a reflection, bearing in mind that
the trip is two ways over the same cable and the time shown will be
double the time for the calculation.
Bob
On Monday, August 8, 2016 12:00 PM, Bob Stewart bob@evoria.net wrote:
Earlier this year, with some help, I pulled the dish off of an old
DishTV antenna on the roof and put a 5V bullet antenna on the mast. I
also pulled a new cable through by attaching it to the old one. The
problem is that I was not able to measure the new cable. So, the
question is, without going back on the roof in this heat, how can I
measure the electrical length of the line I pulled?
I was thinking of using my 8640B signal generator and sending some RF
back up the line to get a quarter wavelength at the null. But that
assumes a lot, including that the other end is open at 3MHz, or
whatever the frequency works out to be, as well as that the high
voltage on the antenna end won't be high enough to blow the LNA.
So, how much RF I can safely send up the line? I've got an 8558B
spectrum analyzer, but it's not on the bench, and it would be easier to
use my scope, which sadly is a 70s vintage Tek 455. Do I put this all
together with a lead from the generator to a tee at the measuring
device and tune for a null? My experience at getting precise
measurements on anything longer than a few inches is effectively none,
but I'd guess that I want less than 0.5V at the LNA during this test.
Oh, and I do have an 8444A tracking generator that can output -10 dbm
as well as a 10 db attenuator within easy access. That could get a
quick spot on the null point.
Most importantly, of course is the question of whether this will even
work.
Bob -
AE6RV -----------------------------------------------------------------
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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.
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.
--
Sent from my Moto-X wireless tracker while I do other things.
Hi Bob,
You want to get something along the lines of ebay item 272331719376 or 262202931320. The boom is pretty important, otherwise how do you get your boards under the microscope if they're not very small? Some time ago, I got a Bausch & Lomb Stereo 3 with 10X oculars and a 0.5 barlow. The zoom scale on the scope reads 0.7 to 3. This, combined with the 10X oculars gives it a zoom range of 7X to 30X. This is a bit strong for doing PCB work, so the 0.5 barlow cuts that in half to 3.5X to 15X which is just about right. I leave the boom at the right height to do soldering on the bench, but don't have the lateral thumbscrew on the boom tightened, so I can move the scope left and right or out of the way. I wouldn't pay extra for a fancy light system like you'll see on many auctions. Instead, I bought an LED light ring to go around the barlow lens on the bottom. It has a brightness control, so it works out well.
As far as the board suppliers, I tried ExpressPCB at first, but they're pretty expensive, and you're stuck with their board size. So, I switched to OshPark.com. They don't supply proprietary board design software, which is fine, because there is a free version of Eagle, or you can use Kicad like I do. (Kicad can output Gerber files.) I believe that both Mouser and DigiKey have free board design software, as well. But, the risk with those is that they either go away or become pay systems.
Bob - AE6RV
-----------------------------------------------------------------
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
From: Bob Albert via time-nuts <time-nuts@febo.com>
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Thursday, August 11, 2016 12:24 PM
Subject: Re: [time-nuts] Working with SMT parts.
What are the important parameters regarding purchase of a stereo microscope? I see some on ebay for around $50; are those good?
Bob
Hi Didier:
Another option is to send the free ExpressPCB files to FAR Circuits for production. This can be very cost effective if
you only need a simple circuit. Vias not supported.
www.farcircuits.net/EXPRESS%20PCB%20DOC.doc
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.
-------- Original Message --------
I concur. I have been using ExpressPCB extensively over the last 2 years
with great satisfaction now that it is possible to get Gerber files from
them.
I typically use the mini board pro service (3 bare boards, 2 sided with
solder mask and silk screen) for prototypes and then buy the Gerbers to
have production quantities done overseas.
The boards are of high quality and the service is very fast at a very
reasonable price.
The only gotcha with regard to Gerber files is that you can only buy
Gerbers for boards that you have actually bought from them, so the process
is to buy the prototypes, then if you are happy with those, buy the Gerbers
for that design.
Didier KO4BB
On Tue, Aug 9, 2016 at 3:06 PM, Brooke Clarke brooke@pacific.net wrote:
Hi:
I've had good luck using any of the the ExpressPCB services that include
solder mask with surface mount parts where the pitch is 0.05" (half normal
DIP) and hand soldering (requires stereo microscope).
http://www.prc68.com/I/BTSG.shtml (battery top signal generator)
http://www.prc68.com/I/Images/ICS525v1o.jpg
http://www.prc68.com/I/SMT.shtml http://www.prc68.com/I/SMT.shtml
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/m
ailman/listinfo/time-nuts
and follow the instructions there.
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.
I use a Nikon and a Meiji that I picked up surplus on the cheap.
Lighting matters. Fostec ring illuminators are okay, but I prefer
something with gooseneck arms so I actually do have shadows. Light from a
particular angle can help rather than nice uniform illumination.
#1 recommendation I have for a stereo microscope for soldering use is get
one that can take a filter disc. In the very least put some saran wrap
around the bottom. Condensing flux vapors make a mess of the optics over
the years.
#2 is recognizing you don't need all that much magnification to do the
work. 50x is a lot of magnification. Way more than you need for 0402
parts.
I've also found that brains are a pretty amazing PID controller. 10x
magnification seems to result in 1/10th the hand shake.
-Bob
On Thu, Aug 11, 2016 at 11:24 AM, Bob Albert via time-nuts <
time-nuts@febo.com> wrote:
What are the important parameters regarding purchase of a stereo
microscope? I see some on ebay for around $50; are those good?
Bob
On Thursday, August 11, 2016 10:00 AM, Didier Juges <
shalimr9@gmail.com> wrote:
I concur. I have been using ExpressPCB extensively over the last 2 years
with great satisfaction now that it is possible to get Gerber files from
them.
I typically use the mini board pro service (3 bare boards, 2 sided with
solder mask and silk screen) for prototypes and then buy the Gerbers to
have production quantities done overseas.
The boards are of high quality and the service is very fast at a very
reasonable price.
The only gotcha with regard to Gerber files is that you can only buy
Gerbers for boards that you have actually bought from them, so the process
is to buy the prototypes, then if you are happy with those, buy the Gerbers
for that design.
Didier KO4BB
On Tue, Aug 9, 2016 at 3:06 PM, Brooke Clarke brooke@pacific.net wrote:
Hi:
I've had good luck using any of the the ExpressPCB services that include
solder mask with surface mount parts where the pitch is 0.05" (half
normal
DIP) and hand soldering (requires stereo microscope).
http://www.prc68.com/I/BTSG.shtml (battery top signal generator)
http://www.prc68.com/I/Images/ICS525v1o.jpg
http://www.prc68.com/I/SMT.shtml http://www.prc68.com/I/SMT.shtml
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/m
ailman/listinfo/time-nuts
and follow the instructions there.
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.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/
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and follow the instructions there.