I'm running tests today with the 25 ohm load connected to the K3/LP-100
with varying lengths of RG-142B/U coaxial cable, in 24 inch increments
out to 120 or 144 inches. The result should be a constant SWR,
neglecting the padding effect of coaxial cable loss, but with the
impedance varying alon
__
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That's a good question, Paul. I have a medium power, 150 ohm load laying
around that I made up a couple years ago for testing purposes. I just
checked it with my VNA and it has an SWR of 2.92, pure resistive. I did a
quick test with the K3 at 25W, and it measured between 2.4 and 2.7 depending
on b
n matching the
>> rig to its load.
>>
>> 73,
>> Wayne
>> N6KR
>>
>>
>>
>> http://www.elecraft.com
>>
>> On Nov 8, 2009, at 7:18 PM, "Edward Dickinson, III"
>> > > wrote:
>>
>&g
> consistently lower than Jack's, ie. 1.6 on most bands with a 2.0 load. Not
> a
> big deal, but as long as you're in there tweaking the code, can you verify
> that it works with non-KAT3 radios as well?
I'm curious -- are those who see a smaller indicated VSWR reading on the K3
meter with a 25-
gt; wrote:
>
>> _
>>
>> From: Jack Smith [mailto:jack.sm...@cliftonlaboratories.com]
>> Sent: Sunday, November 08, 2009 10:00 PM
>> To: Edward Dickinson, III
>> Subject: Re: [Elecraft] K3 SWR Accuracy - reprise
>>
>> Dick:
>>
>> ht
te:
>
>> _
>>
>> From: Jack Smith [mailto:jack.sm...@cliftonlaboratories.com]
>> Sent: Sunday, November 08, 2009 10:00 PM
>> To: Edward Dickinson, III
>> Subject: Re: [Elecraft] K3 SWR Accuracy - reprise
>>
>> Dick:
>>
>> htt
Hi Jack,
Thank you for the time and effort you spent on making and reporting measurements
on the K3 SWR accuracy. You have saved me from the chore of further
investigations.
It is interesting to note the close degree of correlation between the
measurements that you made
using calibrated high acc
Wayne (and Jack) I and at least one other user, have noted the K3 with
ATU sometimes appears to leave a residual C or L in circuit on 10m when
in "bypass" giving lower than expected power into a 50 Ohm load and may
give incorrect TX power calibration as a result. Using the ATU to give a
good SWR fi
> _
>
> From: Jack Smith [mailto:jack.sm...@cliftonlaboratories.com]
> Sent: Sunday, November 08, 2009 10:00 PM
> To: Edward Dickinson, III
> Subject: Re: [Elecraft] K3 SWR Accuracy - reprise
>
> Dick:
>
> http://www.cliftonlaboratories.com/swr_accuracy.htm
>
>
Original Message -
> From: "Kok Chen"
> To: "Elecraft Reflector"
> Cc: "Steve Ellington"
> Sent: Wednesday, November 04, 2009 7:55 PM
> Subject: Re: [Elecraft] K3 SWR Accuracy - reprise
>
>
>
>> On Nov 4, 2009, at 4:41 PM, Steve E
ok Chen"
To: "Steve Ellington"
Cc: "Elecraft Reflector"
Sent: Wednesday, November 04, 2009 8:51 PM
Subject: Re: [Elecraft] K3 SWR Accuracy - reprise
>
> On Nov 4, 2009, at 5:05 PM, Steve Ellington wrote:
>
>> It's called a transmission line transformer an
On Nov 4, 2009, at 5:05 PM, Steve Ellington wrote:
> It's called a transmission line transformer and is very common.
Yes, we all know about them. Just walk 180 degrees on a constant SWR
circle on the Smith Chart, with the transmission line impedance at the
center of the Smith Chart (or use
swap them with
each other. Putting them in series fouls up the readings for both meters.
Steve
N4LQ
n...@carolina.rr.com
- Original Message -
From: "Kok Chen"
To: "Elecraft Reflector"
Cc: "Steve Ellington"
Sent: Wednesday, November 04, 2009 7:55 PM
On Nov 4, 2009, at 4:41 PM, Steve Ellington wrote:
> 4. Example: A full wave dipole center fed with 50 ohm coax. SWR reads
> infinite at the antenna but with 1/4 wavelenth of coax, SWR reads low!
Nope -- the *impedance* at the end of a 1/4 wave transmission line
when it is looking at a very la
the case.
Wes N7WS
Steve
N4LQ
n...@carolina.rr.com
- Original Message -
From: "Phil & Debbie Salas"
To:
Sent: Wednesday, November 04, 2009 5:53 PM
Subject: Re: [Elecraft] K3 SWR Accuracy - reprise
> "How long is the coax between the LP100 sensor and the K3? This
could hook 100 SWR meters in series and
they would all read something different.
Steve
N4LQ
n...@carolina.rr.com
- Original Message -
From: "Phil & Debbie Salas"
To: "Steve Ellington" ;
Sent: Wednesday, November 04, 2009 7:18 PM
Subject: Re: [Elecraft] K3 SWR Accura
:
From: Don Wilhelm
Subject: Re: [Elecraft] K3 SWR Accuracy - reprise
To: elecraft@mailman.qth.net
Cc: "Phil & Debbie Salas"
Date: Wednesday, November 4, 2009, 4:33 PM
I can vouch for Eric's statement. I routinely calibrate KPA100
wattmeters for SWR using a precision 100 oh
Steve,
Just one clarification - a mismatched length of coax will transform the
impedance, but a perfectly matched line will not.
Since we calibrate things at 50 ohms, if the coax is exactly 50 ohms and
the SWR is 1.0:1, no impedance transformation will exist. But real coax
lines are "nominally
Steve Ellington"
To: "Phil & Debbie Salas" ;
Sent: Wednesday, November 04, 2009 5:59 PM
Subject: Re: [Elecraft] K3 SWR Accuracy - reprise
> The first statement is correct. Length of coax will transform impedance
> and cause SWR meters to read differently.
> I've seen
The SWR definitely does not change with line length.
However the SWR _READING_ often does because of the inaccuracy of
inexpensive SWR meters. The SWR reading should depend only on the
relative magnitudes of the forward and reflected power and not on the
phase angle between them. But with inexpe
e what the impedance is then yes, it wouldn't matter where you put
it along the line but such is not the case.
Steve
N4LQ
n...@carolina.rr.com
- Original Message -
From: "Phil & Debbie Salas"
To:
Sent: Wednesday, November 04, 2009 5:53 PM
Subject: Re: [Elecraft] K3
I was using 4 Watts, the external bridge is a taiwan-made "AV-20", I
forgot the brand name. There is a sticker, it says "accuracy 10%".
Today I tested again using 10 Watts, the K3's and the external meters
readout match a lot closer.
With 10 W i can bring the K3s readout to 1.0:1 , with 4 W it was
I can vouch for Eric's statement. I routinely calibrate KPA100
wattmeters for SWR using a precision 100 ohm dummy load (which should
produce a 2.0 SWR). At 40 meters, I get 2.0 if I use a direct
connection with a male to male adapter, with a 1 foot coax, it shows
SWR=2.1 and with a 2 foot coa
> That assumes there is no RF on the exterior of the coax and the SWR
> sensors are ideal. Neither is the case and from personal experience I
> can tell you that the swr meters will change readings based on coax
> length.
The SWR *reading* may change as a function of coax length when current is
Phil & Debbie Salas wrote:
> "How long is the coax between the LP100 sensor and the K3? This can have
> a significant impedance transformation impact as you go to higher
> frequencies, leading to a different indicated SWR at each end."
>
> The impedance changes, but not the SWR. Looking at this on
That assumes there is no RF on the exterior of the coax and the SWR
sensors are ideal. Neither is the case and from personal experience I
can tell you that the swr meters will change readings based on coax length.
73, Eric
Phil & Debbie Salas wrote:
> "How long is the coax between the LP100 se
"How long is the coax between the LP100 sensor and the K3? This can have
a significant impedance transformation impact as you go to higher
frequencies, leading to a different indicated SWR at each end."
The impedance changes, but not the SWR. Looking at this on a Smith Chart,
you can see that yo
Hi all,
This thread is getting rather long but I want to put my 2 cents worth in.
The huge discrepancy between the K3 indicated SWR and the LP-100 shown in
Stewarts original post is *not* normal or expected. Either there is
something wrong with the data or the K3. I am finding that the K3 readin
I don't have a KAT3. I often use an external remote matching unit. I
cannot directly control the lowest SWR found. My linear is somewhat
sensitive to SWR.
At times I have observed a more than satisfactory apparent SWR indication on
my K3 and found my amplifier was less than satisfied.
That's
On Nov 4, 2009, at 12:31 PM, Ron D'Eau Claire wrote:
> I
> It's a non-issue to me since all I care about is knowing I have the
> antenna
> system well matched to the K3.
I have to parrot the "non issue" part of this. I have several SWR
bridges/meters. They rarely agree about anything.
Acc
I've been noticing some apparently anomalies in this area too, for example...
I have two dummy loads - one is a 2kW rated PalStar, which doesn't
appear to be exactly 50ohms (but close enough for usual purposes), and
a Bird Termaline, which is mil-spec 50ohms (and shows as such on a
sweep analyser)
--- On Wed, 11/4/09, Stewart wrote:
Of course, as others have pointed out the value of SWR measured is
immaterial, as the KAT3 will try and adjust to 1:1 when it is selected.
I don't think I would go so far as to say SWR is immaterial.
_
"Elecraft Reflector" ; "Wayne Burdick"
Sent: Wednesday, November 04, 2009 6:10 PM
Subject: Re: [Elecraft] K3 SWR Accuracy - reprise
> 'bout 2 feet.
>
> 73
> Stewart
> On Wed, 04 Nov 2009 09:53:25 -0800, Eric Swartz - WA6HHQ, Elecraft wrote:
>> How long i
Try using a double male connector to put the two SWR sensors right next
to each other and repeat the measurement.
At the higher freq's, even 2 ft of coax can change the indicated SWR,
especially when the actual SWR is 1.9:1 like yours. I regularly see this
when driving an amplifier with a non 1
I've noticed that too, but never though much of it since the external meter
and the K3 agree at 1:1.
Above 1:1, the K3's SWR indication reads lower than the external meter at
100 watts on the lower frequency bands (80, 160) but agrees well with the
external meter on the higher frequency bands. Th
'bout 2 feet.
73
Stewart
On Wed, 04 Nov 2009 09:53:25 -0800, Eric Swartz - WA6HHQ, Elecraft wrote:
> How long is the coax between the LP100 sensor and the K3? This can have
> a significant impedance transformation impact as you go to higher
> frequencies, leading to a different indicated SWR at e
How long is the coax between the LP100 sensor and the K3? This can have
a significant impedance transformation impact as you go to higher
frequencies, leading to a different indicated SWR at each end.
73, Eric
Stewart wrote:
> Hi,
> Now traffic on the new K3 Macro functions has somewhat died d
Slight clarification. I said:
> The K3's SWR bridge has two sensitivity ranges. If you have power set
> to 12 W or lower, the higher-sensitivity range is used. If you have
> power set above 12 W, the lower-sensitivity range is used. This is
> necessary to prevent heating of the transformers in the
Hi Wayne,
Thank you for your prompt and informative replies.
When I first ran my experiment the results I got rather surprised me.
Now you have explained the fact that the KAT3 is never really out of
circuit even in BYPASS mode, and is seeing strays which the LP-100
does not, clarifies the situa
What power level were you using? And what type of external bridge?
The K3's SWR bridge has two sensitivity ranges. If you have power set
to 12 W or lower, the higher-sensitivity range is used. If you have
power set above 12 W, the lower-sensitivity range is used. This is
necessary to prevent
I don't have the KAT3, i use an external homemade tuner and a cheap
swr-meter between it and the K3. Don't know how accurate the swr-meter
is, but i notice that the K3 shows 1.1:1 while the external meter still
reads worse. Fiddling with the controls of the tuner settles the needle
on the external
would
> read different
>> in this case.
>>
>>
>> -Original Message-
>> From: elecraft-boun...@mailman.qth.net
>> [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Stewart
>> Sent: Wednesday, November 04, 2009 2:45 AM
>> To: Elecraft Refle
Hi Stewart,
The KAT3, like all wide-range ATUs, has significant stray reactance,
especially on the higher bands. When you tuned it into 50 ohms, you
created an L-network on each band that tunes out this reactance--at
that one impedance.
In your test, the KAT3 is between the K3's SWR bridge
Wes and all,
It is not unreasonable to expect some frequency dependency in the
detection diodes as well.
The tuner will function properly in any case - it tunes for the lowest
SWR no matter what the exact value of that SWR may be.
Now, if the SWR = 1.0 point was not correct, that would say the
-- On Wed, 11/4/09, Stewart wrote:
From: Stewart
Subject: [Elecraft] K3 SWR Accuracy - reprise
To: "Elecraft Reflector"
Date: Wednesday, November 4, 2009, 1:44 AM
Hi,
Now traffic on the new K3 Macro functions has somewhat died down,
I would like to raise again the issue of the K3&#x
ase.
>
>
> -Original Message-
> From: elecraft-boun...@mailman.qth.net
> [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Stewart
> Sent: Wednesday, November 04, 2009 2:45 AM
> To: Elecraft Reflector
> Subject: [Elecraft] K3 SWR Accuracy - reprise
>
> Hi
;s job - no? I would hope that the K3 SWR meter would read different
in this case.
-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Stewart
Sent: Wednesday, November 04, 2009 2:45 AM
To: Elecraft Reflector
Subject: [Elecr
Just curious how you know that the LP100 is accurate?
-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Stewart
Sent: Wednesday, November 04, 2009 2:45 AM
To: Elecraft Reflector
Subject: [Elecraft] K3 SWR Accuracy - reprise
Hi,
Now traffic on the new K3 Macro functions has somewhat died down,
I would like to raise again the issue of the K3's SWR measurement
accuracy.
I did some tests using dummy loads and a LP-100 meter as follows.
The dummy load is a precision 100W one which I measured with a VNA
and has a VSWR o
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