JA
John Ackermann
Sun, Mar 3, 2013 2:59 PM
I was measuring two OCXO and was getting some quite unusual results -- a
symmetrical frequency cycling of several more than 1e11 p-p, with a
period of around 15 seconds.
I removed an RG-58 3 foot jumper cable that fed 5 MHz from the rear
panel of another OCXO to a patch panel (where it was terminated in 50
ohms), and the noise quieted right down. See the attached frequency plot.
The other OXCO had a similar jumper cable in the path, and although the
two cables were not parallel to each other for any significant distance,
there was still enough signal radiation and pickup to cause a nasty problem.
Lesson learned -- use only double-shielded cable in the oscillator rack
(and in any RF measurement path) from now on.
John
I was measuring two OCXO and was getting some quite unusual results -- a
symmetrical frequency cycling of several more than 1e11 p-p, with a
period of around 15 seconds.
I removed an RG-58 3 foot jumper cable that fed 5 MHz from the rear
panel of another OCXO to a patch panel (where it was terminated in 50
ohms), and the noise quieted right down. See the attached frequency plot.
The other OXCO had a similar jumper cable in the path, and although the
two cables were not parallel to each other for any significant distance,
there was still enough signal radiation and pickup to cause a nasty problem.
Lesson learned -- use only double-shielded cable in the oscillator rack
(and in any RF measurement path) from now on.
John
BC
Bob Camp
Sun, Mar 3, 2013 3:10 PM
Hi
By any chance is the connector a BNC? They have been known to create similar looking issues.
Bob
On Mar 3, 2013, at 9:59 AM, John Ackermann jra@febo.com wrote:
I was measuring two OCXO and was getting some quite unusual results -- a symmetrical frequency cycling of several more than 1e11 p-p, with a period of around 15 seconds.
I removed an RG-58 3 foot jumper cable that fed 5 MHz from the rear panel of another OCXO to a patch panel (where it was terminated in 50 ohms), and the noise quieted right down. See the attached frequency plot.
The other OXCO had a similar jumper cable in the path, and although the two cables were not parallel to each other for any significant distance, there was still enough signal radiation and pickup to cause a nasty problem.
Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on.
John
<austron-fts-beat-note.png>_______________________________________________
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and follow the instructions there.
Hi
By any chance is the connector a BNC? They have been known to create similar looking issues.
Bob
On Mar 3, 2013, at 9:59 AM, John Ackermann <jra@febo.com> wrote:
> I was measuring two OCXO and was getting some quite unusual results -- a symmetrical frequency cycling of several more than 1e11 p-p, with a period of around 15 seconds.
>
> I removed an RG-58 3 foot jumper cable that fed 5 MHz from the rear panel of another OCXO to a patch panel (where it was terminated in 50 ohms), and the noise quieted right down. See the attached frequency plot.
>
> The other OXCO had a similar jumper cable in the path, and although the two cables were not parallel to each other for any significant distance, there was still enough signal radiation and pickup to cause a nasty problem.
>
> Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on.
>
> John
> <austron-fts-beat-note.png>_______________________________________________
> 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.
JA
John Ackermann
Sun, Mar 3, 2013 3:46 PM
Yup, they are BNC (by necessity). I'm still experimenting but it may be
an ill-fitting connector on the cheap patch cable. Switching to a
better quality cable seems to have solved the problem, one way or the other.
John
Bob Camp said the following on 03/03/2013 10:10 AM:
Hi
By any chance is the connector a BNC? They have been known to create similar looking issues.
Bob
On Mar 3, 2013, at 9:59 AM, John Ackermann jra@febo.com wrote:
I was measuring two OCXO and was getting some quite unusual results -- a symmetrical frequency cycling of several more than 1e11 p-p, with a period of around 15 seconds.
I removed an RG-58 3 foot jumper cable that fed 5 MHz from the rear panel of another OCXO to a patch panel (where it was terminated in 50 ohms), and the noise quieted right down. See the attached frequency plot.
The other OXCO had a similar jumper cable in the path, and although the two cables were not parallel to each other for any significant distance, there was still enough signal radiation and pickup to cause a nasty problem.
Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on.
John
<austron-fts-beat-note.png>_______________________________________________
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.
Yup, they are BNC (by necessity). I'm still experimenting but it may be
an ill-fitting connector on the cheap patch cable. Switching to a
better quality cable seems to have solved the problem, one way or the other.
John
----
Bob Camp said the following on 03/03/2013 10:10 AM:
> Hi
>
> By any chance is the connector a BNC? They have been known to create similar looking issues.
>
> Bob
>
> On Mar 3, 2013, at 9:59 AM, John Ackermann <jra@febo.com> wrote:
>
>> I was measuring two OCXO and was getting some quite unusual results -- a symmetrical frequency cycling of several more than 1e11 p-p, with a period of around 15 seconds.
>>
>> I removed an RG-58 3 foot jumper cable that fed 5 MHz from the rear panel of another OCXO to a patch panel (where it was terminated in 50 ohms), and the noise quieted right down. See the attached frequency plot.
>>
>> The other OXCO had a similar jumper cable in the path, and although the two cables were not parallel to each other for any significant distance, there was still enough signal radiation and pickup to cause a nasty problem.
>>
>> Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on.
>>
>> John
>> <austron-fts-beat-note.png>_______________________________________________
>> 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.
>
KR
Kevin Rosenberg
Sun, Mar 3, 2013 4:00 PM
On Mar 3, 2013, at 7:59 AM, John Ackermann jra@febo.com wrote:
Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on.
I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'.
Kevin
On Mar 3, 2013, at 7:59 AM, John Ackermann <jra@febo.com> wrote:
> Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on.
I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'.
Kevin
BC
Bob Camp
Sun, Mar 3, 2013 4:08 PM
Hi
BNC's suffer from shield separation issues and from basic wear out on the connector it's self. Cheap coax = shield seperation. On the connector its self it's either plating or loss of spring in the fingers. The best solution is to cut the connector off the cable. That way at least it doesn't mess you up a second time. Once you get a big enough pile of single ended cables, it's time to get out the crimp tool….
Bob
On Mar 3, 2013, at 10:46 AM, John Ackermann jra@febo.com wrote:
Yup, they are BNC (by necessity). I'm still experimenting but it may be an ill-fitting connector on the cheap patch cable. Switching to a better quality cable seems to have solved the problem, one way or the other.
John
Bob Camp said the following on 03/03/2013 10:10 AM:
Hi
By any chance is the connector a BNC? They have been known to create similar looking issues.
Bob
On Mar 3, 2013, at 9:59 AM, John Ackermann jra@febo.com wrote:
I was measuring two OCXO and was getting some quite unusual results -- a symmetrical frequency cycling of several more than 1e11 p-p, with a period of around 15 seconds.
I removed an RG-58 3 foot jumper cable that fed 5 MHz from the rear panel of another OCXO to a patch panel (where it was terminated in 50 ohms), and the noise quieted right down. See the attached frequency plot.
The other OXCO had a similar jumper cable in the path, and although the two cables were not parallel to each other for any significant distance, there was still enough signal radiation and pickup to cause a nasty problem.
Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on.
John
<austron-fts-beat-note.png>_______________________________________________
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.
Hi
BNC's suffer from shield separation issues and from basic wear out on the connector it's self. Cheap coax = shield seperation. On the connector its self it's either plating or loss of spring in the fingers. The best solution is to cut the connector off the cable. That way at least it doesn't mess you up a second time. Once you get a big enough pile of single ended cables, it's time to get out the crimp tool….
Bob
On Mar 3, 2013, at 10:46 AM, John Ackermann <jra@febo.com> wrote:
> Yup, they are BNC (by necessity). I'm still experimenting but it may be an ill-fitting connector on the cheap patch cable. Switching to a better quality cable seems to have solved the problem, one way or the other.
>
> John
> ----
> Bob Camp said the following on 03/03/2013 10:10 AM:
>> Hi
>>
>> By any chance is the connector a BNC? They have been known to create similar looking issues.
>>
>> Bob
>>
>> On Mar 3, 2013, at 9:59 AM, John Ackermann <jra@febo.com> wrote:
>>
>>> I was measuring two OCXO and was getting some quite unusual results -- a symmetrical frequency cycling of several more than 1e11 p-p, with a period of around 15 seconds.
>>>
>>> I removed an RG-58 3 foot jumper cable that fed 5 MHz from the rear panel of another OCXO to a patch panel (where it was terminated in 50 ohms), and the noise quieted right down. See the attached frequency plot.
>>>
>>> The other OXCO had a similar jumper cable in the path, and although the two cables were not parallel to each other for any significant distance, there was still enough signal radiation and pickup to cause a nasty problem.
>>>
>>> Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on.
>>>
>>> John
>>> <austron-fts-beat-note.png>_______________________________________________
>>> 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.
>>
>
JL
Jim Lux
Sun, Mar 3, 2013 4:30 PM
On 3/3/13 8:00 AM, Kevin Rosenberg wrote:
On Mar 3, 2013, at 7:59 AM, John Ackermann jra@febo.com wrote:
Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on.
I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'.
RG-58 (which by the way, is a spec that officially no longer exists as
part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently
doesn't use PVC insulated wire any more.) comes in myriad forms all of
which bear a passing resemblance to each other. (leaving aside the
RG-58A, RG-58, RG-58C differences).
The term seems to be used for any 50 ohm single shield coax that's about
0.20 inch in diameter with solid polyethylene insulation. You really
need to look at the specific model number to know what the shielding
looks like. It could be anything from a very loose weave of thin copper
strands to something nice and dense.
On 3/3/13 8:00 AM, Kevin Rosenberg wrote:
> On Mar 3, 2013, at 7:59 AM, John Ackermann <jra@febo.com> wrote:
>> Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on.
>
> I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'.
>
RG-58 (which by the way, is a spec that officially no longer exists as
part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently
doesn't use PVC insulated wire any more.) comes in myriad forms all of
which bear a passing resemblance to each other. (leaving aside the
RG-58A, RG-58, RG-58C differences).
The term seems to be used for any 50 ohm single shield coax that's about
0.20 inch in diameter with solid polyethylene insulation. You really
need to look at the specific model number to know what the shielding
looks like. It could be anything from a very loose weave of thin copper
strands to something nice and dense.
VE
Volker Esper
Sun, Mar 3, 2013 6:49 PM
Yes, we all have to learn that lesson...
At the time I use bedea RG-223 and Belden H155 with soldered and crimped
Telegaertner BNC connectors as general purpose cable (up to 2 GHz).
Above that frequency I wouldn't use BNC. If you simply connect your
tracking generator with the spectrum analyzer by using such a BNC cable
there's not one that is absolutely stable when stressing the connector.
I tried several manufacturers, HP, Suhner, Radiall, Rosenberger, it's
always the same.
To make precise measurements I prefer screwed connectors like N or SMA.
Volker
Am 03.03.2013 17:30, schrieb Jim Lux:
On 3/3/13 8:00 AM, Kevin Rosenberg wrote:
On Mar 3, 2013, at 7:59 AM, John Ackermann jra@febo.com wrote:
Lesson learned -- use only double-shielded cable in the oscillator
rack (and in any RF measurement path) from now on.
I've learned that lesson as well. John Miles said that RG-58 is
occasionally referred to as 'soaker hose'.
RG-58 (which by the way, is a spec that officially no longer exists as
part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military
apparently doesn't use PVC insulated wire any more.) comes in myriad
forms all of which bear a passing resemblance to each other. (leaving
aside the RG-58A, RG-58, RG-58C differences).
The term seems to be used for any 50 ohm single shield coax that's
about 0.20 inch in diameter with solid polyethylene insulation. You
really need to look at the specific model number to know what the
shielding looks like. It could be anything from a very loose weave of
thin copper strands to something nice and dense.
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.
Yes, we all have to learn that lesson...
At the time I use bedea RG-223 and Belden H155 with soldered and crimped
Telegaertner BNC connectors as general purpose cable (up to 2 GHz).
Above that frequency I wouldn't use BNC. If you simply connect your
tracking generator with the spectrum analyzer by using such a BNC cable
there's not one that is absolutely stable when stressing the connector.
I tried several manufacturers, HP, Suhner, Radiall, Rosenberger, it's
always the same.
To make precise measurements I prefer screwed connectors like N or SMA.
Volker
Am 03.03.2013 17:30, schrieb Jim Lux:
> On 3/3/13 8:00 AM, Kevin Rosenberg wrote:
>> On Mar 3, 2013, at 7:59 AM, John Ackermann <jra@febo.com> wrote:
>>> Lesson learned -- use only double-shielded cable in the oscillator
>>> rack (and in any RF measurement path) from now on.
>>
>> I've learned that lesson as well. John Miles said that RG-58 is
>> occasionally referred to as 'soaker hose'.
>>
> RG-58 (which by the way, is a spec that officially no longer exists as
> part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military
> apparently doesn't use PVC insulated wire any more.) comes in myriad
> forms all of which bear a passing resemblance to each other. (leaving
> aside the RG-58A, RG-58, RG-58C differences).
>
> The term seems to be used for any 50 ohm single shield coax that's
> about 0.20 inch in diameter with solid polyethylene insulation. You
> really need to look at the specific model number to know what the
> shielding looks like. It could be anything from a very loose weave of
> thin copper strands to something nice and dense.
>
>
>
>
>
> _______________________________________________
> 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.
>
>
HT
Henk ten Pierick
Sun, Mar 3, 2013 6:50 PM
Hi,
The use of double shielded cables does raise the question to what type of connectors to use?
Regards,
Henk
Op 3 mrt. 2013 om 17:30 heeft Jim Lux jimlux@earthlink.net het volgende geschreven:
On 3/3/13 8:00 AM, Kevin Rosenberg wrote:
On Mar 3, 2013, at 7:59 AM, John Ackermann jra@febo.com wrote:
Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on.
I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'.
RG-58 (which by the way, is a spec that officially no longer exists as part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently doesn't use PVC insulated wire any more.) comes in myriad forms all of which bear a passing resemblance to each other. (leaving aside the RG-58A, RG-58, RG-58C differences).
The term seems to be used for any 50 ohm single shield coax that's about 0.20 inch in diameter with solid polyethylene insulation. You really need to look at the specific model number to know what the shielding looks like. It could be anything from a very loose weave of thin copper strands to something nice and dense.
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.
Hi,
The use of double shielded cables does raise the question to what type of connectors to use?
Regards,
Henk
Op 3 mrt. 2013 om 17:30 heeft Jim Lux <jimlux@earthlink.net> het volgende geschreven:
> On 3/3/13 8:00 AM, Kevin Rosenberg wrote:
>> On Mar 3, 2013, at 7:59 AM, John Ackermann <jra@febo.com> wrote:
>>> Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on.
>>
>> I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'.
> RG-58 (which by the way, is a spec that officially no longer exists as part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently doesn't use PVC insulated wire any more.) comes in myriad forms all of which bear a passing resemblance to each other. (leaving aside the RG-58A, RG-58, RG-58C differences).
>
> The term seems to be used for any 50 ohm single shield coax that's about 0.20 inch in diameter with solid polyethylene insulation. You really need to look at the specific model number to know what the shielding looks like. It could be anything from a very loose weave of thin copper strands to something nice and dense.
>
>
>
>
>
> _______________________________________________
> 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.
RD
Robert Darlington
Sun, Mar 3, 2013 7:03 PM
Alligator clips, of course.
-Bob
On Sun, Mar 3, 2013 at 11:50 AM, Henk ten Pierick henk@deriesp.demon.nlwrote:
Hi,
The use of double shielded cables does raise the question to what type of
connectors to use?
Regards,
Henk
Op 3 mrt. 2013 om 17:30 heeft Jim Lux jimlux@earthlink.net het volgende
geschreven:
On 3/3/13 8:00 AM, Kevin Rosenberg wrote:
On Mar 3, 2013, at 7:59 AM, John Ackermann jra@febo.com wrote:
Lesson learned -- use only double-shielded cable in the oscillator
rack (and in any RF measurement path) from now on.
I've learned that lesson as well. John Miles said that RG-58 is
occasionally referred to as 'soaker hose'.
RG-58 (which by the way, is a spec that officially no longer exists as
part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently
doesn't use PVC insulated wire any more.) comes in myriad forms all of
which bear a passing resemblance to each other. (leaving aside the RG-58A,
RG-58, RG-58C differences).
The term seems to be used for any 50 ohm single shield coax that's about
0.20 inch in diameter with solid polyethylene insulation. You really need
to look at the specific model number to know what the shielding looks like.
It could be anything from a very loose weave of thin copper strands to
something nice and dense.
and follow the instructions there.
Alligator clips, of course.
-Bob
On Sun, Mar 3, 2013 at 11:50 AM, Henk ten Pierick <henk@deriesp.demon.nl>wrote:
> Hi,
>
> The use of double shielded cables does raise the question to what type of
> connectors to use?
>
> Regards,
>
> Henk
>
> Op 3 mrt. 2013 om 17:30 heeft Jim Lux <jimlux@earthlink.net> het volgende
> geschreven:
>
> > On 3/3/13 8:00 AM, Kevin Rosenberg wrote:
> >> On Mar 3, 2013, at 7:59 AM, John Ackermann <jra@febo.com> wrote:
> >>> Lesson learned -- use only double-shielded cable in the oscillator
> rack (and in any RF measurement path) from now on.
> >>
> >> I've learned that lesson as well. John Miles said that RG-58 is
> occasionally referred to as 'soaker hose'.
> > RG-58 (which by the way, is a spec that officially no longer exists as
> part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently
> doesn't use PVC insulated wire any more.) comes in myriad forms all of
> which bear a passing resemblance to each other. (leaving aside the RG-58A,
> RG-58, RG-58C differences).
> >
> > The term seems to be used for any 50 ohm single shield coax that's about
> 0.20 inch in diameter with solid polyethylene insulation. You really need
> to look at the specific model number to know what the shielding looks like.
> It could be anything from a very loose weave of thin copper strands to
> something nice and dense.
> >
> >
> >
> >
> >
> > _______________________________________________
> > 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.
>
AM
Alan Melia
Sun, Mar 3, 2013 8:36 PM
Some of the older synchronised signal generators (2-box systems) e.g
Marconi, used TNC connectors with solid coax where signal leakage was likely
to be a problem.
Alan G3NYK
----- Original Message -----
From: "Volker Esper" ailer2@t-online.de
To: time-nuts@febo.com
Sent: Sunday, March 03, 2013 6:49 PM
Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale
Yes, we all have to learn that lesson...
At the time I use bedea RG-223 and Belden H155 with soldered and crimped
Telegaertner BNC connectors as general purpose cable (up to 2 GHz). Above
that frequency I wouldn't use BNC. If you simply connect your tracking
generator with the spectrum analyzer by using such a BNC cable there's not
one that is absolutely stable when stressing the connector. I tried
several manufacturers, HP, Suhner, Radiall, Rosenberger, it's always the
same.
To make precise measurements I prefer screwed connectors like N or SMA.
Volker
Some of the older synchronised signal generators (2-box systems) e.g
Marconi, used TNC connectors with solid coax where signal leakage was likely
to be a problem.
Alan G3NYK
----- Original Message -----
From: "Volker Esper" <ailer2@t-online.de>
To: <time-nuts@febo.com>
Sent: Sunday, March 03, 2013 6:49 PM
Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale
>
> Yes, we all have to learn that lesson...
>
> At the time I use bedea RG-223 and Belden H155 with soldered and crimped
> Telegaertner BNC connectors as general purpose cable (up to 2 GHz). Above
> that frequency I wouldn't use BNC. If you simply connect your tracking
> generator with the spectrum analyzer by using such a BNC cable there's not
> one that is absolutely stable when stressing the connector. I tried
> several manufacturers, HP, Suhner, Radiall, Rosenberger, it's always the
> same.
>
> To make precise measurements I prefer screwed connectors like N or SMA.
>
> Volker
