Re: [Elecraft] K4D for bargain price on eBay

[John Oppenheimer]

So that there's no confusion, will you post one of the PDF file links
here. John KN5L

On 3/12/24 4:24 PM, Jim Brown wrote:
> On 3/12/2024 12:29 PM, John Oppenheimer wrote:
>> Did you measure a Choke Balun, or sometimes known as Common Code Choke
> 
> "The book" are in several pdf applications notes on my website. What I 
> measured is well documented there
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Re: [Elecraft] K4D for bargain price on eBay

[John Oppenheimer]

On 3/12/24 1:31 PM, Jim Brown wrote:
> I wrote the book on this. k9yc.com/RFI-Ham.pdf

Hi Jim, there are a bunch of inductor measurements within the book.

Did you measure a Choke Balun, or sometimes known as Common Code Choke
(CMC)?

John KN5L
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Re: [Elecraft] AT1 Attenuator

[John Oppenheimer]

2-Port VNWA measurements at 7MHz

Switch, VSWR, dB
0 1.01 0.07
1 1.03 1.06
1 1.03 1.06
3 1.02 3.08
6 1.03 6.31
10 1.02 9.78
20 1.05 19.97

VSWR approaches 1.1 at 30MHz with some switch settings.

John KN5L
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[Elecraft] Elecraft Test Equipment Applications

[John Oppenheimer]

Fun today using Elecraft test equipment for purpose of measuring Ferrite
loss as a function of power. K3, DL1, and CP1.

Visit QSL.net, requires password access,

https://forums.qrz.com/index.php?threads/ft240-52-power.855486/page-3#post-6489172
https://forums.qrz.com/index.php?threads/ft240-52-power.855486/page-4#post-6489595

John KN5L
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Re: [Elecraft] A few words about the CP1 bidirectional coupler kit

[John Oppenheimer]

Hi John, good read, thanks,

John KN5L

On 2/6/23 3:52 PM, John Harper wrote:
> Well, maybe a few hundred, plus 3 photos:
> https://ae5x.blogspot.com/2023/02/the-utility-of-elecrafts-cp1-bi.html
> 
> If you're one of the many who now have a tinySA...
> 
> 73,
> John AE5X
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Re: [Elecraft] I need a Sherlock Holmes (weird spurs on 40m)

[John Oppenheimer]

I also had power line interference on 7MHz. Made a shielded loop using a
Hula hoop as support, BL2 for balanced loop to coax, and KX3 receiver.
Didn't take long to DF it out.

John KN5L

On 6/7/22 8:36 PM, Alan Bloom wrote:
> Hi John,
> 
> In this case the Internet is not via DSL, it's via cable.
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Re: [Elecraft] I need a Sherlock Holmes (weird spurs on 40m)

[John Oppenheimer]

Hi Alan,

I've had issues with the service from street to modem. As I understand,
there's a VDSL band which overlaps 7MHz band.

In my case, it was reversed, any transmission on 7MHz would disable TV
and Internet service.

John KN5L

On 6/7/22 7:54 PM, Alan Bloom wrote:
> The ISP is TDS.  They offer up to 1 Gbps internet (I only pay for 200 
> Mbps) via cable.
> 
> Just as a sanity check, I just walked down to the main house and 
> unplugged the 150-foot LAN cable from the modem/router that feeds the 
> router in the granny unit here where the shack is.  As expected, the 
> spurs are still there.  There is no wired connection from the K4 or the 
> desktop computer to the LAN (Wi-Fi only).
> 
> Alan N1AL
> 
> 
> On 6/7/22 18:29, John Oppenheimer wrote:
>> Hi Alan,
>>
>> What is your TV/Internet provider?
>>
>> John KN5L
>>
>> On 6/7/22 6:59 PM, Alan Bloom wrote:
>>> The weird thing about these spurs is how clean and stable they are.
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Re: [Elecraft] I need a Sherlock Holmes (weird spurs on 40m)

[John Oppenheimer]

Hi Alan,

What is your TV/Internet provider?

John KN5L

On 6/7/22 6:59 PM, Alan Bloom wrote:
> The weird thing about these spurs is how clean and stable they are. 
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Re: [Elecraft] Receiver impedance?

[John Oppenheimer]

Hi Walter,

Elecraft receivers, I'm familar with (K2,K3,KX[23], use "Feedback
Amplifiers" for their Pre Amp. The Feedback Amplifiers are designed for
nominal 50 ohm input impedance. Fifty ohm input impedance is somewhat
import for operation of the receiver bandpass filter.

I'll assume detector input impedance, preAmp bypass, is also nominal 50
ohm impedance.

John KN5L

On 5/25/22 11:05 AM, Walter Underwood wrote:
> What is a typical input impedance for modern receivers, or specifically 
> Elecraft receivers? 
> 
> I’m asking because antenna tuners are a frequent question on an SWL group I 
> follow and I’m pretty sure that they are not needed for most situations. If 
> the receiver input impedance is not 50 Ω, that is a big data point.
> 
> My belief is that receivers are generally medium or high impedance, depending 
> on whether the first RF preamp is bipolar or FET, but either way, mostly 
> voltage-oriented.
> 
> And, yes, I know that antenna tuners can be a LPF or HPF, depending on their 
> configuration.
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Re: [Elecraft] OT; large ferrite toroid core?

[John Oppenheimer]

Hi Mike,

Initial permeability can be computed from your values:

Compute 4T permeability=1 (Lo) using core dimensions:
Lo = 0.0004606 * Log10(OD / ID) * Ht * Turns^2 (Ht in mm)
Lo = 0.0004606 * Log10(6 / 2.6) * 14.3 * 16 = 0.0383uH (Ht in mm)
Initial Permeability ui = 6.6 / 0.0383 = 172

Fair-Rite 61 material ui = 125, 52 material ui = 250. If characteristics
are close to 61 or 52 material, then could use it for an HF Choke Balun.

Complex permeability can be plotted out to 20 to 30 MHz range using a
single port VNA. Do you have a VNA? I can walk your through the process
if wanted.

John KN5L


On 10/21/21 1:24 PM, Mike Maloney wrote:
> We were gifted a somewhat large (6"OD, 2.6" ID, 9/16" thick) ferrite core of 
> unknown mix and original use.   On face was marked 6.6uH w/4turns.   My 
> thinking it might make a good common mode RF choke on the output of an 
> inverter generator or on coax feedline.    Not familiar with properties of 
> toroid cores of this size.   Any ideas?
> 73, Mike AC5P
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Re: [Elecraft] Bad Ham Radio Day

[John Oppenheimer]

I've found preferred method for evaluating Ferrite Choke Balun common
mode rejection performance is to measure common mode rejection (CMR).

Some various 43 material examples, which demonstrate CMR is a function
of device inductance.
https://www.kn5l.net/Balun-CM/Balun-43material/

FT140-43 7T CMR measured using four different methods to ensure
correlation and correct CMR measurement process. Also demonstrate
correlation with SimSmith model using Fair-Rite Complex permeability file.
https://www.kn5l.net/Balun-CM/FT140/

Comparing 31 and 43 material which demonstrate, for a given inductance,
43 material results with improved CMR. With equal turns, 31 material has
small CMR improvement.
https://www.kn5l.net/Balun-CM/Balun31-43/

John KN5L

On 9/4/21 9:14 PM, Jim Brown wrote:
> On 9/4/2021 2:48 PM, jerry wrote:
>> 31-mix is supposed to be the hot ticket for HF common mode
>> chokes.  One turn through one core is supposed to be 98 ohms at 5MHz. So 
>> four cores should give me about 400 ohms, which should give a worthwhile 
>> attenuation in a 50 ohm system.  Thanks for the references.
> 
> I'm the guy that did the original work on this, beginning in 2003, when 
> #31 was a brand new mix. I got five of the first #31 toroids from the 
> pre-production run, a few months after I suggested that they would be 
> quite useful. My first publication was a paper to a 2005 international 
> meeting of the Audio Engineering Society, of which I'm a Fellow. First 
> publication to the ham world was RFI-Ham.pdf in 2007. And you are 
> mistaken about the value of four cores at HF. Study that paper. It's a 
> tutorial on how RFI happens and how chokes work.
> 
> 73, Jim K9YC
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Re: [Elecraft] K2 OH, NO, a problem!

[John Oppenheimer]

Hi Jerry,

Is current mode enabled? Described in the manual on page 104, "Reducing
Current Drain for portable Operation."

John KN5L

On 6/25/21 11:29 PM, jerry wrote:
> Well, not a big one.
> 
> Somehow, the radio has decided not to do the bar graph on the display.  
> Instead, it shows a dot - just one display segment illuminated.  I tried 
> the "GrPH" item in the menu - no joy.
> "OFF" works.  "dOt" works.  "bAr" does not work - it displays a dot, 
> just like "dOt".
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Re: [Elecraft] VNA shootout proposal

[John Oppenheimer]

Hi John,

I use my VNWA every few days. Would miss it if gone for a few weeks :-)

Though some thoughts: VNA's are, if calibrated and temperature stable,
inherently accurate. Requirements are:

Must have Log sample spacing.

2 port must have 12-term compensation. Required to normalize Port 2 Zin
to 50.00 Ohm.

For measurements over 100MHz, must have Arbitrary calibration capability.

A way to test capability is measuring Ferrite complex permeability. An
example is: https://www.kn5l.net/S21adapter/FR43-material/

Web page is in notebook style with several iterations. Final measurement
under heading "FT50-43 Panel Jack Fixture."

Follow link for "Calibration Process"

In the example above, I predict Fair-Rite 43 material measurement, using
HP E4991a with 16454A fixture (1MHz-3.0GHz), has a 2.47nH calibration error.

A dynamic range test:
https://groups.io/g/VNWA/message/20899

John KN5L

On 6/25/21 5:53 PM, John Harper wrote:
> I'm as interested as anyone else who might have one to know the accuracy
> and reliability of these affordable VNA's, whether nano- or the one from
> SDR-Kits.
> 
> I have a variety of VNA's available but am lacking the SDR-Kits model.
> Wouldn't it be nice if we knew where it stood compared to the newer
> nanoVNA's costing a fraction of the price for the same dynamic range and a
> higher upper frequency limit?
> 
> Also, how do the hobby VNA's compare to lab-grade VNA's at HF and up to 1.2
> GHz?
> 
> If you own an SDR-Kits VNA, can do without it for 3 weeks and trust me to
> return it to you, please see my offer here:
> 
> https://ae5x.blogspot.com/2021/06/vna-shootout.html
> 
> John AE5X
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Re: [Elecraft] Pin 1 and Grounding Post on the K3s

[John Oppenheimer]

Hi Peder,

K3s grounding post is also one of the board ground plane to enclosure
connections. See Assembly manual, Page 68, Figure 97.

John KN5L

On 6/23/21 9:58 PM, Peder Kittelson wrote:
> I have been following the Pin 1 grounding discussions with interest.  I
> have one of the last Elecraft K3s Transceivers built at the factory and
> love using it.
> 
> I wonder if the grounding post on the back of the K3s attaches directly to
> the case or runs to the motherboard ground?
> 
> I currently have the grounding post attached to an RF grounding strap
> running as a single point ground between all my devices to keep from
> voltage differences.
> 
> Should I be concerned?
> 
> 73 to all,
> 
> Peder, W7RPK
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Re: [Elecraft] K3/K3s keying with bugs, ponderings

[John Oppenheimer]

Hi Roy,

A question best answered with a measurement. Appended to:
https://www.kn5l.net/debounce555/

is waveform for a Bug running just under 40WPM. One small weight at
fastest setting.

John KN5L

On 5/10/21 11:17 AM, Roy wrote:
> Relating to contact bounce, I wonder what the typical length of a bounce 
> is? We hear QRQ stations operating at 60+ wpm all the time. If Elecraft 
> designed to smooth out such short "dots" from semi-auto key bounce, then 
> perhaps a K4 would not allow 70+ wpm speeds to be sent either?
> 
> 73,  Roy   K6XK
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Re: [Elecraft] Elecraft CW keying mistakes using bugs - semiautomatic keys

[John Oppenheimer]

Hi Ian,

All Bugs have some amount of contact bounce. K3 does not have debounce
circuitry. I use a debounce device between Bug and rig. Several can be
found on the internet.

I made one: https://www.kn5l.net/debounce555/

John KN5L

On 5/9/21 12:38 PM, IK4EWX wrote:
> Dear friends, Elecraft K3S owners, now I am sure that the K3S is a CW
> transceiver suitable only for the use of paddles with its internal keyer or
> external pc keying.
> I had already noticed with the Begali Intrepid bug that the K3S introduced
> extra points that were not my manipulation errors. 
> Today, using a spectacular and magnificent Mecograph mod. 3 of 1908,
> restored to maximum efficiency, in transmission at about 25 wpm, the
> Elecraft K3S, both in qsk and in vox, generates a lot of errors in
> transmission. It generate understandable CW.
> The same bug used on a Ten Tec Corsair II and a Cubic 102BXA is instead
> perfect, with an excellent cw and without any errors.
> There is and has been certainly a problem with the key input circuit on the
> K3S. 
> I hope that the same design and construction error will not happen again on
> the K4 Elecraft.
> Otherwise it will certainly not be a bug user transceiver.
> It is a lot better an IC7300, which my friend IK4DCT uses with his two
> Mecographs without any problems.
> Ian IK4EWX
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Re: [Elecraft] K3 assembly issue

[John Oppenheimer]

Hi Adrian, welcome to the hobby and to the Elecraft list,

Wow, that's quite a collector's item! I'd consider asking Elecraft what
they'd charge to assemble and align for you.

John KN5L

On 2/14/21 3:32 PM, KJ7SOY wrote:
> Hi everyone! I’m new to the list and to Elecraft radios and HAM in general. 
> Thanks for bearing with me while I learn!
> 
> I picked up an unassembled K3 at an auction three weeks ago. It’s been 
> sitting in a box with most of the boards sealed in their anti-static bags 
> since 2009. I’ve hit a snag and I’m hoping someone here can help. 
> 
> I have the rev B RF board and I’m doing the manual’s resistance tests. 
> Voltage regulators U12 and U13 are both supposed to test at > 150 ohms. U12 
> passes but U13 tests at 87 ohms. This unit has never been powered up so I 
> suspect it has to be a bad regulator. I can solder a board just fine and 
> assemble PCB’s but I’m not overly comfortable with hardware debugging. I’ve 
> removed the side cover and checked for loose boards, bad connections, etc. 
> with no success. Anyone have any ideas how I should proceed? Do I just 
> replace the regulator? Do some other debugging?
> 
> Thanks!
> 73
> -Adrian
> KJ7SOY
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[Elecraft] P3 dynamic Ref Level ?

[John Oppenheimer]

Is there a P3 ability for Ref Lev settings for receive antenna versus
antenna 1? Trying to evaluate SNR difference between transmit and
receive antennas. Receive antenna has about 35dB lower gain than
transmit antenna. 80M band.

John KN5L
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Re: [Elecraft] Oscilloscope recs

[John Oppenheimer]

Hi Lou,

Rigol DS2202A has time in saved image. But not date! Not sure why not
date, as it does have internal date for file system time stamp.

yes, prefer to have display with knobs and buttons!

Good luck with your search.

John KN5L

On 12/9/20 8:40 AM, Louandzip via Elecraft wrote:
> I saw the comment about the screen shots being saved to the computer not 
> having time stamps.  Back in the day, my screen shot Polaroids that got taped 
> into an paper notebook didn't have time stamps either, so I can def see the 
> benefit there.
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Re: [Elecraft] Oscilloscope recs

[John Oppenheimer]

Hi All,

Two price steps in Rigol/Siglent low price Oscilloscopes, $300 and $600.
$300 class has smaller and lower resolution display. Smaller display
results with limited size raster graphics output image files. Recently
upgraded to a Rigol DS2202A. Much larger display. Example image files
shown here:
https://www.kn5l.net/VNWA-Calibrate/OpAmpFixture/

John KN5L
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Re: [Elecraft] [K3] Issue with HI CUR on 12m

[John Oppenheimer]

Hi Jim,

The SimSmith model includes Fair-Rite complex permeability files, which
is the basis of the Ferrite model.

John KN5L

On 10/13/20 2:23 PM, Jim Brown wrote:
> On 10/13/2020 11:41 AM, John Oppenheimer wrote:
>> Jim, can you be more specific with flaws within the SimSmith model?
> 
> John, I suggest that you study my email and the references I cited. Also 
> study the early pages in the Fair-Rite catalog, one devoted to each 
> material, showing plots of mu' and mu'' vs frequency.
> 
> 73, Jim K9YC
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Re: [Elecraft] [K3] Issue with HI CUR on 12m

[John Oppenheimer]

Jim, can you be more specific with flaws within the SimSmith model?

I've updated https://www.kn5l.net/Balun-CM/Balun31-43/ with Balun CMRR
window image. So that others don't need to load SimSmith and model from
the ZIP file link.

John KN5L

On 10/13/20 12:45 PM, Jim Brown wrote:
> you clearly don't understand how 
> ferrite common mode chokes work.
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Re: [Elecraft] [K3] Issue with HI CUR on 12m

[John Oppenheimer]

Hi Jim,

For high power Balun Applications, most critical parameter is Ferrite
core loss which causes core heating. Core loss, parallel resistance
(Rp), can be computed from complex permeability data from Fair-Rite.

https://www.kn5l.net/Balun-CM/Balun31-43/
Models FT240 10T with 31 and 43 materials. G.Zo is selected to indicate
maximum possible core dissipation watts. Maximum core dissipation
accrues when ground to antenna external conductor electrical length =
1/2 wavelength multiples. 1/2 wavelength multiples reflects ground
impedance to the Balun.

As shown, at 1.8MHz, maximum core dissipation for 1kW key down could be
4W for 31 material and 3.6W for #43 material. Probably not enough
difference to worry about.

The two CMRR traces, red and yellow, are below about -20dB. Difference
in choking ability is insignificant in this range.

The model includes a parallel capacitor for self resonance. Though is
not critical, as reactance does not result in heating. Core loss, Rp,
causes core heat rise.

All in all, not much difference between 43 and 31 for these two Baluns.

John KN5L

On 10/12/20 9:05 PM, Jim Brown wrote:
> #43 is a terrible material for the HF 
> bands.
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Re: [Elecraft] KX2 / WM1 Reporting Conflict

[John Oppenheimer]

Hi Jim,

Both the KX2 and W1 need to be calibrated to a standard. The W1 manual
4.5V is a rough calibration. As I remember, KX2's are calibrated at the
factory at some (I've forgotten) power level. Both the KX2 and W1 are
somewhat non linear.

For my shack, I've decided that a DL1, along with an accurate 10M Ohm
Fluke DVM is the standard. No adjustment required and is as accurate as
the 1% load resistors, DL1 diode drop voltage, and DVM accuracy.

John KN5L

On 9/30/20 1:46 PM, James Bennett via Elecraft wrote:
> Wondering if anyone can help on this - I’ve got a KX2 and W1 Power Meter. The 
> power out on the KX2 does not match what the W1 is reporting. I have the W1 
> connected to my MacBook Pro displaying the serial data being sent to it.
> 
> I just verified that the W1 voltage at the TP1 connector is exactly 4.5 
> volts, per the manual. I ran the KX2 Manual Transmit Gain Calibration. The 
> KX2 is showing exactly 6.0 watts into a dummy load, going through the W1. The 
> serial data reported by the W1 is 7.20 watts, consistently. Also, the KX2 
> firmware is the most recent.
> 
> So, who is wrong - KX2 or W1? And what can I do to resolve it?
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Re: [Elecraft] KX-3 TX current draw?

[John Oppenheimer]

Additional comments:

Same test at 7MHz results with about 1A current. Suggesting KX3 power
amplifier efficiency difference between 7 and 50 MHz.

Using same DL1, added Elecraft W1 and MS utility to measure SWR. At 50
MHz KX3 displays SWR = 1.5 whereas W1 indicates SWR = 1.1:1.

May I suggest W1 closer to instrument grade measurement than KX3
internal SWR measurement.

John KN5L

On 5/9/20 8:34 AM, John Oppenheimer wrote:
> Hi Drew,
> 
> 50 MHz TX constant 4 W carrier:
> 
> KX3 #1658
> KX3 PS 13.2 during XMIT
> ATU bypass
> Elecraft DL1
> KX3 SWR 1.5
> Current = 2.3A
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Re: [Elecraft] KX-3 TX current draw?

[John Oppenheimer]

Hi Drew,

50 MHz TX constant 4 W carrier:

KX3 #1658
KX3 PS 13.2 during XMIT
ATU bypass
Elecraft DL1
KX3 SWR 1.5
Current = 2.3A

John KN5L

On 5/8/20 6:52 PM, Mooneer Salem wrote:
> I got 2.36A current consumption @ 5W using a dummy load and the TX button
> on 50.100MHz USB with my KX3 (S/N 3262). The voltage dropped from 13.74V to
> 13.67V during transmit. (Measured using an in-line Powerpole meter attached
> between a 54Ah LiFePO4 battery and the KX3.) Hopefully this helps!
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Re: [Elecraft] VF Varies With Frequency

[John Oppenheimer]

A typical, Type RG-58A Vf measurement, as a function of frequency, is
shown in second plot: https://www.kn5l.net/transMeasure/

Vf is frequency dependent.

John KN5L

On 4/1/20 4:45 PM, Mpridesti via Elecraft wrote:
> Requested technical comment from a long established coaxial cable 
> manufacturer on this topic. 
> 
> This was the response:
> 
>The Vp is not measured at any frequency and is independent of frequency.
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Re: [Elecraft] KPA1500 RFI on 12m

[John Oppenheimer]

Hi Eric,

What is the measured SWR on 12M?

Way different band, worked VP6R 40M CW using K2 at ~15 watts and ground
plane 19' vertical.

John KN5L

On 10/24/19 3:08 PM, eric norris via Elecraft wrote:
> Force 12 C3 antenna is not resonant on 12m.  Using the K3 barefoot, the 
> internal atu tunes the antenna fine.  Bypassing the K3 atu, but still running 
> barefoot into the KPA1500 atu, the KPA atu loses it's mind and goes in and 
> out of TUNE mode uncommanded
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Re: [Elecraft] Cruise Lines

[John Oppenheimer]

Hi Joe,

Some cruise lines do allow ham radio. A presentation:
https://wparc.us/presentations/Cruise-Ham-Radio-Presentation-1.pdf

KX3 on Carnival:  https://www.kn5l.net/hp0/

John KN5L
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Re: [Elecraft] Elecraft CW Net Report

[John Oppenheimer]

Hi Kevin, A fun experiment. You were S3 at peaks with S3 urban noise.
All I could pull out was your pattern. Sending my call to match your
pattern. Ken, W0CZ, was only copy-able signal with 579 at peaks.

Station on this end, K2 at 15W with Ground Plane 19 foot vertical.

John KN5L

On 9/29/19 11:45 PM, kevinr wrote:
> Forty meters was better.  The weakest signal was from John, KN5L.  
> On peaks he was hitting S3 but in the troughs of QSB he was gone.
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Re: [Elecraft] Unbuilt K1 Found

[John Oppenheimer]

Was listed in a local group downsizing shack FS email.

John KN5L

On 9/27/19 5:10 AM, KE8LXD wrote:
> I am too looking for an unbuilt k1 kit for a while but don’t luck yet. May I
> ask where you found it?
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[Elecraft] Unbuilt K1 Found

[John Oppenheimer]

They are out there. Yesterday I purchased K1 #2573. Documentation
suggests vintage about late 2008, kit including errata F-8.

Has noise blanker option, but no ATU option. Anyone have an unbuilt ATU kit?

John KN5L
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[Elecraft] Get on air more often reason #6

[John Oppenheimer]

Antenna of choice is portable ground plane vertical using Buddipole
components. Storing tripod and mast on back porch. This morning found
all three Virsa-T 3/8x20 threads with a mud cap and larva inside.

Need to use antenna more often! Have fun out there in Elecraft land,
John KN5L
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Re: [Elecraft] QRP FD KX2 Batteries & FT8 Report

[John Oppenheimer]

Covered in ARRL FD FAQ:
http://www.arrl.org/files/file/Field-Day/2019/2019-FD-FAQ-RevA.pdf

convenient backyard operations on property of home stations remain
either Class D (commercial power) or Class E (emergency power), even if
home antenna structures are not used

John KN5L

On 6/25/19 1:52 PM, Bill Frantz wrote:
> Interesting question. He reports:
> 
>> When our club’s plans for FD fell through at the last minute I set up 1B 
>> with my trusty KX-2 with a Bioenno battery and two internal KX2 battery pacs 
>> on my back porch. Got a Par 40-20-10 end-fed up about 40’ in a north-south 
>> orientation only to find band conditions here were pretty bad here in the 
>> north with QRN, QSB and faint signals at best.
> It sounds like he was not depending on any of the home station 
> infrastructure e.g. antennas, so I think that he was in class 
> 1B, one or two person portable or even perhaps 1Bb if he was 
> battery QRP. YMMV.
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Re: [Elecraft] Measuring SSB RMS Power

[John Oppenheimer]

Searching email archives, found this comment from Lyle in KX3 list:

On 2/8/14 4:04 PM, Lyle Johnson wrote:
> The KX3 SSB compression algorithm is a bit different than the K3 for a
> number of reasons.  Reducing the bandwidth, removing the very low
> audio frequencies, etc., are all part of the algorithm design.

Therefore, simple power gain may not be the full story. Per above, power
is concentrated within a narrower BW as compression is increased.

Though I wonder if TXEQ with significant low frequency attenuation
changes compression power gain.

For testing, KX3 TX EQ is set to "KX3 Optimal" in:
https://www.kn5l.net/KX3-TxEq/

John KN5L

On 6/20/19 8:38 AM, John Oppenheimer wrote:
> Using DL1 with Oscilloscope to measure KX3 SSB RMS power:
> 
> https://www.kn5l.net/ssbpower/
> 
> Question, is this technique correct?
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Re: [Elecraft] Measuring SSB RMS Power

[John Oppenheimer]

Hi Bob,

Viewing pink noise with an oscilloscope, it is continuous, where as
speech has breaks.

The web page is evaluating both expected power to a load and compression
gain. Using a little over six second recorded speech. Recording contains
fast spoken words, mostly numbers and a few "this is a test" etc, for
maximum power over time. Evaluating scope shoot, about 25 words during
six second recording. Not even close to pink noise.

John KN5L

On 6/20/19 11:27 AM, Bob McGraw K4TAX wrote:
> To evaluate speech use a pink noise source.  That is the standard source 
> signal for acoustic measurements. 
> 
> Bob, K4TAX
> 
> 
> Sent from my iPhone
> 
>> On Jun 20, 2019, at 10:34 AM, John Oppenheimer  wrote:
>>
>> Hi Don,
>>
>>> On 6/20/19 9:21 AM, Don Wilhelm wrote:
>>> John,
>>>
>>> That connection is OK if you realize that your scope is reading the DC 
>>> voltage developed by rectifying the RF from 1/2 of the load.  You still 
>>> have to use the power formula that is in the DL1 manual.
>>
>> Well yes, power references are DCV^2 / 25
>>
>> DdB ratios computed using voltage ratios in the form of
>> 20 * Log(v1/v2). For example, 0 compression Pep/Pav dB =
>> 20 * log(15.3/5.24) = 9.3. I do need to flip the table title to Pav/Pep
>> for proper negative dB values, Done.
>>
>>> I prefer to allow the 'scope to read the full peak RF voltage.  Connect 
>>> the 'scope probe to the side of one resistor which is connected to the 
>>> BNC jack (one of the leads closest to the BNC), and the 'scope ground 
>>> probe to one or the resistor leads furthermost away from from the BNC jack.
>>
>> Using detected RF envelope for oscilloscope average RF measurement at
>> each digitized point during long, six second, trace. This will result
>> with increased accuracy when measuring modulated speech.
>>
>> John KN5L
>>
>>>> On 6/20/2019 9:38 AM, John Oppenheimer wrote:
>>>> Using DL1 with Oscilloscope to measure KX3 SSB RMS power:
>>>>
>>>> https://www.kn5l.net/ssbpower/
>>>>
>>>> Question, is this technique correct?
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Re: [Elecraft] Measuring SSB RMS Power

[John Oppenheimer]

Hi Bob,

Document Table 1, Line 7. speech = V/5*2^.5. which is same as Vrms/5.
Using measured RMS ratios, Vrms=15.3, 15.3/5 = 3V, compared to measured
5.24V.

Speech is rather undefined, so not too worried about the discrepancy. My
speech with no pauses is ~= Vrms / 3.

Really what is being evaluated is gain resulting from speech compression.

John KN5L


On 6/20/19 9:29 AM, Bob McGraw K4TAX wrote:
> Here is a paper on the topic. This covers the correct procedure. 
> 
> http://www.eng.auburn.edu/~troppel/courses/TIMS-manuals-r5/TIMS%20Experiment%20Manuals/Student_Text/Vol-A1/a1-12.pdf
> 
> 
> 73
> 
> Bob, K4TAX
> 
> 
> Sent from my iPhone
> 
> On Jun 20, 2019, at 8:38 AM, John Oppenheimer  <mailto:j...@kn5l.net>> wrote:
> 
>> Using DL1 with Oscilloscope to measure KX3 SSB RMS power:
>>
>> https://www.kn5l.net/ssbpower/
>>
>> Question, is this technique correct?
>>
>> John KN5L
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Re: [Elecraft] Measuring SSB RMS Power

[John Oppenheimer]

Hi Don,

On 6/20/19 9:21 AM, Don Wilhelm wrote:
> John,
> 
> That connection is OK if you realize that your scope is reading the DC 
> voltage developed by rectifying the RF from 1/2 of the load.  You still 
> have to use the power formula that is in the DL1 manual.

Well yes, power references are DCV^2 / 25

DdB ratios computed using voltage ratios in the form of
20 * Log(v1/v2). For example, 0 compression Pep/Pav dB =
20 * log(15.3/5.24) = 9.3. I do need to flip the table title to Pav/Pep
for proper negative dB values, Done.

> I prefer to allow the 'scope to read the full peak RF voltage.  Connect 
> the 'scope probe to the side of one resistor which is connected to the 
> BNC jack (one of the leads closest to the BNC), and the 'scope ground 
> probe to one or the resistor leads furthermost away from from the BNC jack.

Using detected RF envelope for oscilloscope average RF measurement at
each digitized point during long, six second, trace. This will result
with increased accuracy when measuring modulated speech.

John KN5L

> On 6/20/2019 9:38 AM, John Oppenheimer wrote:
>> Using DL1 with Oscilloscope to measure KX3 SSB RMS power:
>>
>> https://www.kn5l.net/ssbpower/
>>
>> Question, is this technique correct?
>>
>
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[Elecraft] Measuring SSB RMS Power

[John Oppenheimer]

Using DL1 with Oscilloscope to measure KX3 SSB RMS power:

https://www.kn5l.net/ssbpower/

Question, is this technique correct?

John KN5L
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Re: [Elecraft] KX3 PS Voltage Display Accuracy?

[John Oppenheimer]

On 6/11/19 3:34 PM, George Pasek wrote:
> as if there was a series diode involved with the display voltmeter.

Hi George,

KKX3 uses a series Schottky doide for reverse voltage protection. The
KX3 displays voltage after the diode.

John KN5L
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Re: [Elecraft] Prospective K4

[John Oppenheimer]

And easy on a battery for field operation, < 400mA Receive and optimal
PA biasing for efficient for 5W and 20W to 50W operation.

John KN5L
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Re: [Elecraft] New bug, popping on dah side

[John Oppenheimer]

TJ, your six miles line of sight, what to come by and borrow it for a
while to see if it's a fix?

John KN5L

On 4/28/19 12:11 PM, John Oppenheimer wrote:
> Nice!! A Begali Intrepid,
> 
> All bugs will have contact bounce. K3 does not handle them well at all,
> same for KX3/2. K2 is much more tolerant. Though normally for the dot side.
> 
> I fixed it with a home-brew debouncer:
> https://www.kn5l.net/debounce555/
> 
> Others cam be found on the WWW. It was fun designing and building one.
> 
> John KN5L
> 
> On 4/28/19 12:02 PM, TJ Campie wrote:
>> I hooked up a new bug (begali intrepid) and am noticing popping when keying
>> dahs - I if I add a 4.7uF bypass across the key line it clears this up but
>> it???ll sometimes make it so there???s no dits. I can???t figure this one 
>> out -
>> is there something I need to do to make sure there???s no extra garbage when
>> I???m keying?  (Contacts are clean)
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Re: [Elecraft] New bug, popping on dah side

[John Oppenheimer]

Nice!! A Begali Intrepid,

All bugs will have contact bounce. K3 does not handle them well at all,
same for KX3/2. K2 is much more tolerant. Though normally for the dot side.

I fixed it with a home-brew debouncer:
https://www.kn5l.net/debounce555/

Others cam be found on the WWW. It was fun designing and building one.

John KN5L

On 4/28/19 12:02 PM, TJ Campie wrote:
> I hooked up a new bug (begali intrepid) and am noticing popping when keying
> dahs - I if I add a 4.7uF bypass across the key line it clears this up but
> it???ll sometimes make it so there???s no dits. I can???t figure this one out 
> -
> is there something I need to do to make sure there???s no extra garbage when
> I???m keying?  (Contacts are clean)
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Re: [Elecraft] HW-16 Re: Latest Elecraft NEWS

[John Oppenheimer]

Took a look at Heath's HW-16 design. Quite ingenious: Using the PA
cathode bypass capacitors and current through a diode to shunt the
receiver front end during transmit. Early diode QSK operation. And a
neon bulb relaxation oscillator, using grid block keying voltage, for CW
sidetone.

I enjoy putting vintage stuff on the air for SKN. Heath did not
integrating their separates well back in the day, relying on 110V
antenna relays. I may have some DX-60A/HG-10B/HR-1680/HS-1681 ideas for
next year!

John KN5L
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Re: [Elecraft] Non-Resonant Antennas and Chokes

[John Oppenheimer]

On 1/13/19 11:24 PM, Jim Brown wrote:
>> The instrument used to measure this is quite simple.
>   I'd be very interested in how you're measuring the current at the 
> antenna feedpoint. :) That is NOT so simple.

The common mode current can be measured 1/2 wavelength from the
feedpoint. Here is an example:

https://www.kn5l.net/Balun-CM/

MFJ has a clamp-on current meter which can be used.

John KN5L
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Re: [Elecraft] Speaker Wire Loss Study

[John Oppenheimer]

The speaker wire loss study page:

https://www.kn5l.net/SpeakerWire/

is updated with #22 measurement and model. A good demonstration of vinyl
RF absorption. The larger #18 speaker wire with greater vinyl content
results with an increased loss over #22 speaker wire.

Where the #18 vinyl loss is three time the copper loss, the #22 vinyl
loss is two times the copper loss.

John KN5L

On 12/18/18 8:46 PM, John Oppenheimer wrote:
> There were some comments about speaker loss and the contribution of loss
> as a result of vinyl dielectric. A way to evaluate is to measure a
> length of speaker wire and compare to an air dielectric equivalent. Here
> is an example:
> 
> https://www.kn5l.net/SpeakerWire/
> 
> The Air dielectric equivalent model is for #18 with spacing for a Zo
> match with the speaker wire, 117 Ohm.
> 
> Note that at 10 MHz, the speaker wire loss is over three times the air
> dielectric equivalent.
> 
> A DC resistance of the speaker wire suggested that the wire size is
> actually closer to #19. Tough measuring these very low DC resistances,
> so decided to assume #18 for the air dielectric model.
> 
> The speaker wire loss and Zo used a Zoc and Zsc data set. There are
> links to the two files for verification.
> 
> Check my math!
> 
> John KN5L
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[Elecraft] Speaker Wire Loss Study

[John Oppenheimer]

There were some comments about speaker loss and the contribution of loss
as a result of vinyl dielectric. A way to evaluate is to measure a
length of speaker wire and compare to an air dielectric equivalent. Here
is an example:

https://www.kn5l.net/SpeakerWire/

The Air dielectric equivalent model is for #18 with spacing for a Zo
match with the speaker wire, 117 Ohm.

Note that at 10 MHz, the speaker wire loss is over three times the air
dielectric equivalent.

A DC resistance of the speaker wire suggested that the wire size is
actually closer to #19. Tough measuring these very low DC resistances,
so decided to assume #18 for the air dielectric model.

The speaker wire loss and Zo used a Zoc and Zsc data set. There are
links to the two files for verification.

Check my math!

John KN5L
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Re: [Elecraft] wire for random wire antenna using kx3

[John Oppenheimer]

On 12/17/18 3:11 PM, Jim Brown wrote:
> This overly simplified equation fails to account for proximity effe
Proximity effect will effect impedance, which will then effect the loss.

The wire loss equation is dependent on the TL Zo. The previous example
was for Zo=100. Using Zo=75, wire loss for #12 is 0.47 dB/100. For the
Teflon, that would leave 0.47 dB for dielectric loss. This is sounding
closer.

John KN5L

> On 12/17/2018 12:58 PM, John Oppenheimer wrote:
>> On 12/17/18 1:58 PM, Jim Brown wrote:
>>> In order of loss at dB/100 ft at 10 MHz from low to high, the
>>> Teflon #12 is lowest at 0.94dB, then RG400 at 1.22 dB (about the same as
>>> RG58), then #12 THHN at 1.34 dB. #12 or #10 enameled copper had the
>>> greatest loss, 2.4 dB/100 ft.
>> Hi Jim,
>>
>> Two parallel transmission line is the easiest of all to evaluate using a
>> RF resistance table and knowing the impedance of the line.
>> http://ve3efc.ca/wireohms.htm
>>
>> The wire loss is dB = 10 * log10((Zo + WireR)/Zo)
>>
>> Assuming Zo=100 for the #12 Teflon and THHN. R at 10 MHz = 4.24/100 =
>> 8.48/200.
>>
>> Wire dB = 10 * log10(108.48 / 100) = 0.35 dB
>>
>> Using the two values above at 10 MHz, 0.94 and 1.34, the dielectric loss
>> is 0.59 dB and 1 dB. The dielectric loss is about two and three times
>> the wire loss.
>>
>> John KN5L
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Re: [Elecraft] wire for random wire antenna using kx3

[John Oppenheimer]

On 12/17/18 1:58 PM, Jim Brown wrote:
> In order of loss at dB/100 ft at 10 MHz from low to high, the 
> Teflon #12 is lowest at 0.94dB, then RG400 at 1.22 dB (about the same as 
> RG58), then #12 THHN at 1.34 dB. #12 or #10 enameled copper had the 
> greatest loss, 2.4 dB/100 ft.

Hi Jim,

Two parallel transmission line is the easiest of all to evaluate using a
RF resistance table and knowing the impedance of the line.
http://ve3efc.ca/wireohms.htm

The wire loss is dB = 10 * log10((Zo + WireR)/Zo)

Assuming Zo=100 for the #12 Teflon and THHN. R at 10 MHz = 4.24/100 =
8.48/200.

Wire dB = 10 * log10(108.48 / 100) = 0.35 dB

Using the two values above at 10 MHz, 0.94 and 1.34, the dielectric loss
is 0.59 dB and 1 dB. The dielectric loss is about two and three times
the wire loss.

John KN5L
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Re: [Elecraft] [K3] SWR - Numerical Indication

[John Oppenheimer]

Hi Dick,

The Elecraft list does not accept attachments. Send to me directly.

John KN5L

On 12/2/18 4:14 PM, Dick Dickinson wrote:
> Hi John,
> 
> Per your suggestion, I ran a sweep of my 40 meter vertical with the K3 /
> K3EZ software.
> 
> I then measured at ~20 kHz steps with my MFJ-259B.
> Both sets of measurements were taken from the PL-259 that plugs into the rig
> or 259B.
> 
> Conditions were ~60 degrees F, ground nearly saturated.
> 
> Attached is an image of the results.
> 
> Kindly,
> Dick - KA5KKT
> 
> 
> ---
> 
> Hi Dick,
> 
> An EZNEC and SimSmith model of the on ground 1/4 wave vertical:
> https://www.kn5l.net/images/SS-KA5KKT-vertical.png
> 
> SimSmith R1 represents ground loss, the value set to establish a 50 ohm load
> at the transmitter, G in SimSmith.
> 
> According to the models, the 7 to 7.3 MHz SWR is a little below 1.3.
> 
> A flat measurement using the K3 SWR meter seams reasonable. My suggestion is
> to use a Antenna Analyzer to measure the antenna and system.
> 
> John KN5L
> 
> On 12/2/18 12:16 AM, Dick Dickinson wrote:
>> I have a full-size monoband vertical for 40 meters.  Simple 
>> architectural aluminum tapering from 1 �� (?) in 6� telescoping 
>> sections.  The radial field is designed to provide a 50 ohm match at 
>> the feed point�12 � 13�+ radials.  It is fed directly�no matching 
>> device with RG-213 from the remote antenna switch about 50� away at my 
>> tower.  The coax from the rig to the remote antenna switch is 
>> estimated to be ~ 50� in length.  A lot of the time running K3EZ to 
>> sweep the band (typically 20 watts), it will indicate a
>> 1.0:1 SWR from 7.0 MHz to 7.3 MHz in 20 kHz steps.  Occasional 
>> deviation from one K3EZ run to another might be due to variations in 
>> moisture content of the ground or less than perfect connection to the 
>> vertical�an uncommon situation.  The K3 shows the same readings.
>>
>> Is this 1.0:1 SWR across the entire 40 meter band curious or remarkable?

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Re: [Elecraft] [K3] SWR - Numerical Indication

[John Oppenheimer]

Hi Dick,

An EZNEC and SimSmith model of the on ground 1/4 wave vertical:
https://www.kn5l.net/images/SS-KA5KKT-vertical.png

SimSmith R1 represents ground loss, the value set to establish a 50 ohm
load at the transmitter, G in SimSmith.

According to the models, the 7 to 7.3 MHz SWR is a little below 1.3.

A flat measurement using the K3 SWR meter seams reasonable. My
suggestion is to use a VNA to measure the antenna and system.

John KN5L

On 12/2/18 12:16 AM, Dick Dickinson wrote:
> Thanks for the explanation,  John.
> 
> I’m not an electronically educated fellow, merely just seeking the
> practical.  
> 
> A resolution to my post was provided in the suggestion that the apparent
> 1.1:1 SWR might be the result of common mode current.  Sure enough when I
> installed a 1:1 current balun at the feed point of the antennas (2
> perpendicular Inverted Vees with a switchable common feed point), the value
> went from 1.1:1 to 1.0:1 and the bottom of the SWR curves which also
> broadened out.
> 
> Still that doesn’t explain why the K3 was showing 1.1:1 while passing 1.0:1
> information to K3EZ, or so it seems.  I don’t think that the K3EZ is
> ‘measuring SWR’ rather merely posting information it is getting from the
> K3…no different measuring device or location.  Perhaps it is a sort of
> ‘rounding error.’  By the way, for those who haven’t come across it, K3EZ
> has the great feature of being able to step the K3 across a frequency range,
> momentarily key it, step again, etc. and plot in text an SWR chart…a handy
> feature for working with an antenna installation.
> 
> Following is a situation that perhaps you have the theoretical background to
> explain…
> 
> I have a full-size monoband vertical for 40 meters.  Simple architectural
> aluminum tapering from 1 ¼” (?) in 6’ telescoping sections.  The radial
> field is designed to provide a 50 ohm match at the feed point…12 – 13’+
> radials.  It is fed directly…no matching device with RG-213 from the remote
> antenna switch about 50’ away at my tower.  The coax from the rig to the
> remote antenna switch is estimated to be ~ 50’ in length.  A lot of the time
> running K3EZ to sweep the band (typically 20 watts), it will indicate a
> 1.0:1 SWR from 7.0 MHz to 7.3 MHz in 20 kHz steps.  Occasional deviation
> from one K3EZ run to another might be due to variations in moisture content
> of the ground or less than perfect connection to the vertical…an uncommon
> situation.  The K3 shows the same readings.
> 
> Is this 1.0:1 SWR across the entire 40 meter band curious or remarkable?
> 
> Dick – KA5KKT
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Re: [Elecraft] [K3] SWR - Numerical Indication

[John Oppenheimer]

Hi Dick,

An EZNEC and SimSmith model of the on ground 1/4 wave vertical:
https://www.kn5l.net/images/SS-KA5KKT-vertical.png

SimSmith R1 represents ground loss, the value set to establish a 50 ohm
load at the transmitter, G in SimSmith.

According to the models, the 7 to 7.3 MHz SWR is a little below 1.3.

A flat measurement using the K3 SWR meter seams reasonable. My
suggestion is to use a Antenna Analyzer to measure the antenna and system.

John KN5L

On 12/2/18 12:16 AM, Dick Dickinson wrote:
> I have a full-size monoband vertical for 40 meters.  Simple architectural
> aluminum tapering from 1 ¼” (?) in 6’ telescoping sections.  The radial
> field is designed to provide a 50 ohm match at the feed point…12 – 13’+
> radials.  It is fed directly…no matching device with RG-213 from the remote
> antenna switch about 50’ away at my tower.  The coax from the rig to the
> remote antenna switch is estimated to be ~ 50’ in length.  A lot of the time
> running K3EZ to sweep the band (typically 20 watts), it will indicate a
> 1.0:1 SWR from 7.0 MHz to 7.3 MHz in 20 kHz steps.  Occasional deviation
> from one K3EZ run to another might be due to variations in moisture content
> of the ground or less than perfect connection to the vertical…an uncommon
> situation.  The K3 shows the same readings.
> 
> Is this 1.0:1 SWR across the entire 40 meter band curious or remarkable?
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Re: [Elecraft] [K3] SWR - Numerical Indication

[John Oppenheimer]

Hi Dick,

Some numbers: using the K3 Schematic, "K3S RF Board" Sheet 2, Section
B1. The power meter uses a series Schottky diode detector. The low
reasonable resolution is about 0.3 VDC, or 0.3 * .707 = 0.21 Vrms out of
the directional coupler.

The Power for 0.21 Vrms is:
0.21^2 / 50 = .88 mW
Assuming a 20 dB coupler 1:10 turns ratio, 0.88mW * 100 = 0.88W
reflected power.

Assuming forward power of 100 watts and 0.88 watt reflected power the
return loss is:
10 * log(100 / 0.88) = 20.6 dB

Using the calculator:
https://www.allaboutcircuits.com/tools/vswr-return-loss-calculator/
20.6 dB Return Loss computes to VSWR = 1.222

Therefore, the best lowest estimated K3 VSWR, assuming a 20 dB coupler,
is about 1.2.

Check my numbers.

John KN5L


On 7/27/18 9:58 AM, Dick Dickinson wrote:
> I've noticed that I'm not showing a reading of less than 1.1:1 SWR on my
> antennas per K3 SWR Numerical Readout.  K3EZ will record 1.0:1 SWR in band
> sweeps.
> 
> Can the K3(S) Numerical Display show 1.0:1 SWR?  If so, is there a likely
> reason why K3EZ will show 1.0:1 while my K3 will only go as far down as
> 1.1:1?
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Re: [Elecraft] K2 Narrow Spaced DR Measurement

[John Oppenheimer]

I believe I understand the low level IMD values not matching the line.
Looking at the Sherwood table, the K2 2kHz DR is "Phase Noise" limited.
Makes sense that phase noise would muck with the low values. Within
Ron's presentations it is mentioned that ARRL tried to solve the problem
with very narrow filters to remove the phase noise.

The 3rd order line slope is defined as two! Seams to me, the simple
approach is to find the line, as was done in the plot (notice the line
equation has "2*x"), and simply extend the line to the noise floor.

If the page is reloaded, there is a new "S3" line in the K2 plot to
demonstrate where the phase noise is an issue, about 12 dB below S3, or
S1 signals. Don't know about others, but the noise floor of my antennas
is well above S1, closer to S3 on a good day.

John KN5L


On 10/29/2018 08:38 AM, John Oppenheimer wrote:
> While evaluating a receiver design, a K2 Narrow Spaced Dynamic Range
> measurement was performed to validate the test bench. The K2 plot is on
> the page: https://www.kn5l.net/newReceiverProject/plot-IMD/
> 
> If the two line equations are used, the Noise floor is -138 dBm and 2kHz
> dynamic range is 87 dB. These are close to the Sherwood values of -136
> and 80. The K2 settings are my normal operation IF/AF BW settings, which
> is a little narrower than the Sherwood measurement parameters.
> 
> The question is the low level IMD measurement points do not follow the
> line equation. Is this expected?
> 
> Guess I need to order a $60 Mini-Circuits ZFSC-2-6+
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[Elecraft] K2 Narrow Spaced DR Measurement

[John Oppenheimer]

While evaluating a receiver design, a K2 Narrow Spaced Dynamic Range
measurement was performed to validate the test bench. The K2 plot is on
the page: https://www.kn5l.net/newReceiverProject/plot-IMD/

If the two line equations are used, the Noise floor is -138 dBm and 2kHz
dynamic range is 87 dB. These are close to the Sherwood values of -136
and 80. The K2 settings are my normal operation IF/AF BW settings, which
is a little narrower than the Sherwood measurement parameters.

The question is the low level IMD measurement points do not follow the
line equation. Is this expected?

Guess I need to order a $60 Mini-Circuits ZFSC-2-6+

John KN5L
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Re: [Elecraft] Data transmission on 30 meters with PX3 problem

[John Oppenheimer]

On 09/02/2018 07:56 AM, Don Wilhelm wrote:
> That W3EDP antenna is a strong suspect, as is any off-center fed antenna 
> or end fed antenna.  They can produce large amounts of RF in the shack.

Hi Gwen,

Don is correct. The W3EDP with a large choke Balun, as pictured, between
the Unun and KX3 is an OCF Doublet with a resonant frequency of 11 MHz.
It is rather difficult, if not impossible, to isolate a dipole end
impedance using a choke Balun. The KX3, being at the high impedance
point on 30 meters, will experience a rather high RF voltage.

A way to determine if the rig is part of the antenna is to use what I
call a "touch test." Observe SWR while transmitting, if touching the KX3
antenna BNC jack causes the SWR to change, then the KX3 is part of the
antenna. At the extreme, the touch results with a RF burn. I have
experience RF burn at 15 watts.

John KN5L
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Re: [Elecraft] K2 a little deaf? FIXED!

[John Oppenheimer]

On 07/03/2018 04:21 PM, w2bvh wrote:
> The MDS problem is now apparently fixed!

Great news Lenny! I got interested and spent the afternoon measuring my
K2. Once having the results, I had to send them! And wanted to test my
new test equipment.

The K2 is an amazing radio. I'm glad that the Elecraft team is keeping
the kit available.

John KN5L K2 #7212
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Re: [Elecraft] K2 a little deaf?

[John Oppenheimer]

On 07/02/2018 01:22 PM, w2bvh wrote:
> _XFil BW Hz)    MDS (dBm)
> _400  -125

Measured K2; 14 MHz with 400 Hz BW using XG3 and Fluke 87V (True RMS
with averaging mode). With full AF gain, the two -107 dBm / off voltages
were 322.3 mV and 12.5 mV, => -135.2 dB MDS

K2 sidetone pitch is 600 Hz.

AGC ON, 50 uV input sets one LED segment above S9

Using a new Rigol DG1023Z, set to 13.8 mVPP and a VNWA measured 73.78 dB
attenuator. 12.6 / 368.4 => -136.3 dB MDS. The 1023 accuracy is +-1mV,
or about +-0.65 dB.

John KN5L
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Re: [Elecraft] K2 a little deaf?

[John Oppenheimer]

Hi Lenny,

In the past I've used the "Measuring Receiver Sensitivity" found in the
XG3 manual:
http://www.elecraft.com/manual/E740154%20XG3%20Owner%27s%20Manual.pdf
to be rather close to published K2 numbers.

John KN5L
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Re: [Elecraft] KPA-1500 ATU not working well

[John Oppenheimer]

Here is a picture and some plot images:

http://www.kn5l.net/Elecraft/CP1/

Not super accurate 60 and 100 Ohm loads, but provides an insight of the
coupler operation.

John KN5L

On 06/22/2018 04:15 PM, Wes Stewart wrote:
> I don't quite understand your methodology but there is one, apparently little 
> known caveat with the use of the "Elecraft" coupler topology.    AFAIK, this 
> was 
> first used by John Grebenkemper, KI6WX, in his Tandem Match, described in 
> QST, 
> January 1987.
> 
> Paul Kiciak, N2PK, mentions in his paper, "An HF In-Line Return Loss And 
> Power 
> Meter", that this coupler suffers from poor input match at lower frequencies. 
>  
> So the SWR meter has high SWR!
> 
> If the CP1 wasn't so expensive, I'd buy one just to measure it.
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Re: [Elecraft] KPA-1500 ATU not working well

[John Oppenheimer]

Putting the Elecraft CP1 through the paces with a 2 port VNA can be
enlightening. The CP1 seems to be representative of Elecraft directional
couplers across the line. There's a picture of the W2 high power HF
coupler in the manual, it's just larger cores.

Sweeping a 20 dB CP1 across the band with a VNWA with a 60 Ohm load,
1.2:1, results with a relative constant -40 dB reflected gain and a -20
forward gain. A closer match to 50 Ohm fall's apart with a wide -40 db
to -70 dB dip at 7 MHz reflected across the band at 50 Ohm.

I can agree, 1.2 : 1 is about the limit.

John KN5L

On 06/22/2018 01:11 PM, Wes Stewart wrote:
> That's a return loss of ~20 dB.  Now I have 
> no idea of what the directivity of the coupler is in the KAT500 or KPA1500 
> but 
> considering it has to work from 1.8 to 54 MHz and to keep the numbers easy, 
> 20 
> dB wouldn't be unreasonable.
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Re: [Elecraft] KPA1500 Linearity

[John Oppenheimer]

Hi Scott,

I wonder how the linearity of the two power meters was evaluated?

Some years ago I checked the K3 and KX3 power meter against two other
meters. They were just within 10%
http://www.kn5l.net/Elecraft/Power.html

John KN5L

On 06/19/2018 04:56 PM, K9MA wrote:
> I just repeated the linearity measurements, on both 40 and 15 meters.  I 
> used the KPA1500 meter to measure output, and the K3 power setting for 
> input.
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Re: [Elecraft] K2 initial power ramp after band change

[John Oppenheimer]

Hi Bob,

The K3s, KX3, and KX2 use a similar ALC power control design.

John KN5L

On 06/17/2018 07:47 AM, Bob McGraw K4TAX wrote:
> I've noticed a bit of the same thing on my K3S.   Not an issue but I 
> view as a nice safety feature preventing overshoot and over drive of my 
> KPA500.
> 
> 73
> 
> Bob, K4TAX
> 
> On 6/17/2018 7:07 AM, John Oppenheimer wrote:
>> Hi Martin,
>>
>> The power ramp up is normal behavior. The K2 uses requested power
>> control (Page 92, "Requested vs. Actual Power:" paragraph)
>>
>> With a per band set value (Page 111, "Microcontroller" paragraph, "ALC,
>> which is used on CW to maintain the user-specified power level across
>> all bands.")
>>
>> When changing bands, the output power is sampled by the microcontroller
>> resulting with a change in the transmitter ALC to increase power. The
>> ALC action requires a few dits or TUNE to complete.
>>
>> John KN5L K2 #7212
>>
>> On 06/17/2018 01:43 AM, Martin Sole wrote:
>>> After a band change the first dit, or two, is not at full power.
>>> There seems to be an initial ramp up after which all is good and I don't
>>> see any fluctuation in power. Supply is 13.5 volts when producing full
>>> power, about 13.9 with just the receiver running. Full power current on
>>> 28Mhz is showing on the display as 2.66A. I can see the ramp up on the
>>> bar graph, it shows one bar for the first 3-4 dots then ramps up to all
>>> 10 bars. I have confirmed the same with an external power meter.
>>> Anything I can do about this?
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Re: [Elecraft] K2 initial power ramp after band change

[John Oppenheimer]

Hi Martin,

The power ramp up is normal behavior. The K2 uses requested power
control (Page 92, "Requested vs. Actual Power:" paragraph)

With a per band set value (Page 111, "Microcontroller" paragraph, "ALC,
which is used on CW to maintain the user-specified power level across
all bands.")

When changing bands, the output power is sampled by the microcontroller
resulting with a change in the transmitter ALC to increase power. The
ALC action requires a few dits or TUNE to complete.

John KN5L K2 #7212

On 06/17/2018 01:43 AM, Martin Sole wrote:
> After a band change the first dit, or two, is not at full power. 
> There seems to be an initial ramp up after which all is good and I don't 
> see any fluctuation in power. Supply is 13.5 volts when producing full 
> power, about 13.9 with just the receiver running. Full power current on 
> 28Mhz is showing on the display as 2.66A. I can see the ramp up on the 
> bar graph, it shows one bar for the first 3-4 dots then ramps up to all 
> 10 bars. I have confirmed the same with an external power meter. 
> Anything I can do about this?
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Re: [Elecraft] OT antenna question

[John Oppenheimer]

Hi Mike,

An EZNEC model using 30 feet AGL and Q=200 for the coils, has a very
close match the the reported values.

20M, the antenna does not seem to degrade form a simple dipole with a
Gain of about 6 dBi at about 30 degrees elevation.

80M, it's about 5 dBi at 90 degrees elevation. Expected from a low
dipole. The impedance at resonance is about 25 Ohm, so should have a SWR
about 2. A lower measured SWR may be the result of other system loses.

I'd suggest this antenna is a good option for the constraints imposed.

John KN5L

On 05/28/2018 11:39 AM, Michael Blake wrote:
> The center sections of the dipole are tuned for resonance at about 14.15 MHz 
> and the end sections, past the loading inductors on each dipole leg, are 
> tuned for resonance a 3.7 MHz.  The resonance dips at both frequencies are 
> quite sharp and the SWR on both bands is less than 1.5 to 1.
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Re: [Elecraft] Samuel Morse's birthday (Friday, April 27th); good excuse to break out your old hand keys

[John Oppenheimer]

I was inspired by Wayne's announcement to setup outside on my back
porch.  I decided that Morse code is Morse code independent of the key
and used a memory keyer and Vibroplex Iambic key.

The weather in Texas was wonderful!

Calling CQ resulted with several QSOs. It was a fun day.

The setup:
http://www.kn5l.net/SBM/

John KN5L
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Re: [Elecraft] KX3 keying connection to amp question?

[John Oppenheimer]

Hi Ed,

The KX3 specification rates the key line at: "Accessory I/O (ACC2 Jack)
KEYLINE: 30 V, 100 mA max, open drain;" on page 54.

The amplifier should also have a specification. As long as the amp is
under 30V and 100 ma, all will be OK with a direct connection. If the
amp does not have a specification, amp key input measurements can be
performed with a voltmeter and an amp-meter.

John KN5L

On 03/12/2018 10:30 AM, Eddy Avila wrote:
> Greetings, can anyone suggest how to connect a KX3 to a non-Elecraft amp
> keying circuit? I'm thinking I should use a small reed relay to do the
> keying. The amp uses the typical grounding a pin on the amp to key up
> amplifier.
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Re: [Elecraft] KXPA100 DC current at 20 50 watts

[John Oppenheimer]

Thank you Jan!

Also a thank you to the private direct reports.

I'm in a temporary limited shack condition. To KIS, using a K2/10 with a
battery. While sending an endless string of auto-keyer 10W CQs on 20M my
mind wondered to: what is the addition battery drain for 3 dB?

Testing a K3, the bias current for the 100W amplifier is about 5A. I
wondered what the KXPA100 bias current is? Based on the reported
numbers, it's about 7A.

There's been a bunch of list comments about the amazing K2. I agree!
Looking at the Elecraft shipping page, there's been a K2 run. Long live
the K2.

John KN5L

On 03/12/2018 07:56 AM, Jan wrote:
> At 10W    3.0A  and 14V    KX3 alone
> 
> At 20W    10A   and 14V    KX3 + KXPA100
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[Elecraft] KXPA100 DC current at 20 50 watts

[John Oppenheimer]

Hi KXPA100 users,

Can you report the DC input current at 20 and 50 output watts? Actual
measurements will be most helpful.

John KN5L
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[Elecraft] Old Coax, was RG-8X

[John Oppenheimer]

The discussion about old coax reminded me of a recent acquisition. A
couple of weeks ago I went through my old childhood home in FL, just
before it was sold, to look for "stuff" from the past. The property had
a shed, which predated our home, which had old radio stuff in it when I
was young. Looked high and low for something "radio." Finally, up in the
rafters of the shed was a coil for coax with UHF connectors. It predates me.

https://www.icloud.com/sharedalbum/#B0iGhtLJ3GJNmWk

When were those connectors used? Yes, I cleaned off the crud that came
off with a damp cloth.

John KN5L
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Re: [Elecraft] Antenna Analyzer

[John Oppenheimer]

The SARK 110 is very small with many features:

http://www.sark110.com/

John KN5L
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[Elecraft] FR - KX2 max output now 12 watts (experimental)

[John Oppenheimer]

Used the new FW during my early morning 40M CW session. Used KX2 #80
with external LiFePO4 battery and inline W1 Power Meter. Antenna SWR =
1.3. The W1 12W LED does turn on. Measured DL1 power is 11.8 watts.
Ambient operating temperature was 22 C.

Sent many CQs before receiving an answer. Had two long QSOs. Maximum PA
temperature during CQs and conversations was 41 C.

John KN5L
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[Elecraft] KX3 RTC only HW request

[John Oppenheimer]

Hi Elecraft list,

I've had a KX3 for over five years, never installed internal batteries,
never plan to.

I miss having a builtin clock. Sure would be nice to have a RTC board
option, no charging circuitry, with a button cell to maintain clock
time. And FW access to the time correction registers as in the KX2.

John KN5L
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Re: [Elecraft] KX3 with BL2 Question

[John Oppenheimer]

Hi Stan:

Post ten.

There are two ways to approach this, just put something up, or measure
and optimize. When using the KX3 ATU, both methods will provide similar
results.

An 88 foot Doublet and feedline is modeled using EZNEC and SimSmith. The
results found here:
http://www.kn5l.net/Doublet88/

The Balun, both 1:1 and 4:1 is modeled with a perfect conventional
transformer block "A." The KX3 ATU is modeled with the L-C network block
"LC1." A five foot RG-58A/U between the Balun and KX3 is added.

For modeling, Wireman 551 is used and tuned for optimal results on 40
and 20. As shown, a 1:1 Balun results with the best match with SWR below
1.5:1 on both 40 and 20 at the KX3. With system loss below 1 dB.

For this antenna, other bands will have a better match with a 4:1 Balun,
with loses below 1.5 dB.

What is shown is that there is only about 0.5 dB difference between the
optimal and just put it up approach on 40 and above. Using a BL2 and
switching between 1:1 and 4:1 depending on the band.

A short antenna will have a very low impedance, causing the additional
feedline loss to increase significantly, Greater than 4.5 dB is for 80.

John KN5L
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Re: [Elecraft] K3 TVI on 40 meters only

[John Oppenheimer]

May find some information about the issue here:
http://adslm.dohrenburg.net/uverse/

It will depend on which VSDL frequency is being used by the modem. My
modem seemed to pick the high end of 40 meters most of the time.

John KN5L

On 08/25/2017 09:16 PM, Jim Brown wrote:
> I can't think of a mechanism whereby ANY ham rig could be the CAUSE of 
> interference to cable TV or DSL.
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Re: [Elecraft] K3 TVI on 40 meters only

[John Oppenheimer]

Hi Mike,

Did you replace the uVerse modem recently? I had the same 40M problem
after replacing the modem. Google the issue, I believe you'll find
similar experiences.

John KN5L

On 08/25/2017 05:24 PM, Mike Pilgrim wrote:
> have TVI in my u-Verse TVs when using the
> K3 on 40 meters
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Re: [Elecraft] KX2 versus K3 Keyer Speed

[John Oppenheimer]

Hi Phil,

Yes there is a little difference.

One standard for WPM can be found in:
https://en.wikipedia.org/wiki/Morse_code
as T = 1200 / W or WPM = 1200 / T
Where T is dot duration in mS.

To remove weighting, using an oscilloscope to measure Dot and Space
time. The keyer is using the micro-controller, which is doing other
things, therefore there is a little jitter. To filter jitter out,
oscilloscope averaging is enabled.

K3  116.0 mS (Dot+Space) = 20.7 WPM
KX2 114.8 mS (Dot+Space) = 20.9 WPM

John KN5L


On 08/11/2017 09:54 AM, Phil Hystad wrote:
> I think I have detected a subtle difference between the keyer speed of my KX2 
> and my K3.  Is this possible?  How far off?  About one word per minute I 
> think.  The KX2 being faster that is.  Thus, I run my K3 at 20 wpm as my 
> normal speed and my KX2 at 19 wpm to obtain the same feel.  Defininately not 
> large enough to be a bother, I am mostly just curious as to whether this is 
> true.
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Re: [Elecraft] KX2 CW Speed

[John Oppenheimer]

Hi Scott,

Measuring the KX2 DOT period with KYR-SP set to 32 WPM is 34.6 ms. Which
equates to 34.7 WPM.

KX2 #80
John KN5L

On 08/02/2017 12:49 PM, K9MA wrote:
> According to the RBN reports, my KX2 seems to send about 2 wpm faster 
> than the set speed, like 34 vs 32.  Has anyone else noticed this?
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Re: [Elecraft] [KX3] Re: Kx2 paddle issue

[John Oppenheimer]

This is the response I received from Elecraft support:

On 06/27/2017 01:34 PM, Elecraft Support wrote:
> To your question, yes, we are now using a drop of Locktite Blue (not
> Red) on the threads for the 2 screws that hold the round contacts in
> place.

John KN5L

On 07/24/2017 10:45 AM, KENT TRIMBLE wrote:
> The issue is not that the paddles don't leave the factory fully tested 
> and operational, but that the stand-offs (E700348) loosen after a period 
> of time from normal use.
> 
> As posted by several of us previously, the fix is simply to place a 
> small dab of Loctite Blue on the threads of the two flathead screws 
> (E700277) which secure the stand-offs.
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Re: [Elecraft] KX2 heatsink

[John Oppenheimer]

On 06/19/2017 10:41 AM, Wayne Burdick wrote:
> - Running from a lower supply voltage (e.g., the 11 V internal battery)
>   should reduce power dissipation

With external 13.8V input, power lowered to 5W at 3 minutes 48 seconds.

With internal battery, at 8 minutes, the PA temperature was 60C.

John KN5L
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Re: [Elecraft] KX2 heatsink

[John Oppenheimer]

On 06/19/2017 10:41 AM, Wayne Burdick wrote:
> - Running from a lower supply voltage (e.g., the 11 V internal battery)
>   should reduce power dissipation

This is counter to what I had thought! But:

With external 13.8V input, power lowered to 5W at 3 minutes 48 seconds.

With internal battery, I gave up at after 8 minutes, with PA temperature
at 60C.

Maybe a new KX2 11V power supply is needed for dx-peditions similar to
Linas' adventure to Aland Islands.

John KN5L
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Re: [Elecraft] KX2 heatsink

[John Oppenheimer]

Hi Linas,

My KX2 dropped from 10W to 5W at 3 minutes 48 seconds of key down,
starting at 25C.

John KN5L
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Re: [Elecraft] New KX2 beta firmware available with built-in CW/Data logging function

[John Oppenheimer]

Hi Wayne,

Testing the new logging feature in 2.77. A couple of suggestions:

When dumping the log using LG; can the dump stop after dumping the last
valid character, rather then a long string of "---" ?

Can the memory keyer operations be logged. Maybe just a M# or some other
character string which can be identified as a memory keyer with number
operation. Maybe an "R" for repeat.

John KN5L
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[Elecraft] KX2 MENU:TIME Feature Request

[John Oppenheimer]

Hi Wayne,

I'd like a change which sets seconds to zero when tapping the 3 button?

John KN5L
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Re: [Elecraft] The "Kinda Random Antenna"

[John Oppenheimer]

501 ladder line #18 solid CCS copper thickness is 0.0717 mm
http://copperweld.com/sites/copperweld.com/files/w30ccs-ed5230.pdf

RF skin saturation is well below 1 MHz using the calculator:
http://owenduffy.net/calc/SkinDepth.htm

551 is #18, 19/30 stranded, #30 CCS copper thickness is 0.0178 mm

John KN5L

On 02/01/2017 01:18 PM, Lynn W. Taylor, WB6UUT wrote:
> This may not always be possible.
> 
> Copper-clad steel exists because it's stronger than copper.  Wind, ice, 
> or simply a long span can exceed the strength of copper, and then you 
> don't have an antenna at all.
> 
> "Over-engineering" by making the wire bigger also makes it heaver and 
> gives it a larger cross section (more windage).
> 
> I guess you could take your large diameter copper and wrap it around 
> something else to hold it up, but that's basically the idea behind 
> copper clad steel.
> 
> To me, the earlier post means that not all copper-clad wire is suitable 
> for all antennas -- with #553 as an example.
> 
> 73 -- Lynn
> 
> On 2/1/2017 10:57 AM, Clay Autery wrote:
>> Well then...  that seems to vindicate my desire to avoid CCS wire and
>> "overengineer" with the use of larger wire diameters.
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Re: [Elecraft] The "Kinda Random Antenna"

[John Oppenheimer]

Wireman 553 uses a 19 strand Copper Clad Steal (CCS) conductor which
results with very thin copper cladding. 553 is skin saturated at about
15 MHz. The loss at 1.8 MHz is approximately 0.21 dB per 100 feet.

http://www.kn5l.net/wm553/

Using EZNEC and SimSmith for the antenna below results with 13.8 dB
transmission line loss. Slightly greater loss then Wes' calculations.

John KN5L

On 01/31/2017 04:12 PM, Wes Stewart wrote:
> A 130' dipole, 60' high on 160 has a feed point Z of ~4.5 -j1200.  One 
> hundred 
> feet of Wireman 553 (typical ladderline) will transform this to ~7.5 +j16 at 
> the 
> input.  The total loss in this "low-loss" line is over 12 dB.
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Re: [Elecraft] KX3 Transmit EQ Settings

[John Oppenheimer]

A K3/P3 can be used to measure the KX3 SSB TX bandpass. The process is
to speak random words for several seconds while monitoring with a P3 in
"Peak" mode. After about 30 seconds the display will stabilize.

The K3 filter width is 2.1 KHz 350 - 2450

Here are some measurements:
http://kn5l.net/KX3-TxEq/

John KN5L
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Re: [Elecraft] KX3 Transmit EQ Settings

[John Oppenheimer]

The Heil site as some suggestions here:
https://www.heilsound.com/amateur/support/dsp-settings/all-things-elecraft

Using a K3/P3 to measure the response curve, I use:
-16 -16 -16 -2 +3 +9 +16 +8

John KN5L

On 11/09/2016 03:28 PM, k4mmg@gmail.com wrote:
> Any suggestions on what EQ settings for good SSB communication using the 
> Elecraft hand mic?
> 
> Any suggestions on what EQ settings for good SSB communications using any 
> other type of mike?
> 
> I am not seeking any fancy audio profile.
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Re: [Elecraft] KX3 tuner loss?

[John Oppenheimer]

Hi Barry,

The tuner will have negligible compared to the transmission line
miss-match loss.

Take a look at the KX3 list messages:

https://groups.yahoo.com/neo/groups/KX3/conversations/messages/60190
https://groups.yahoo.com/neo/groups/KX3/conversations/messages/60192

John KN5L

On 11/03/2016 09:20 AM, Barry N1EU wrote:
> I'd appreciate knowledgeable estimates of the loss in dB through the KX3
> ATU when working into a 44ft (NorCal) doublet fed with twinlead, with or
> without a BL2 balun inline, on 20/17/15M.
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Re: [Elecraft] Performance of the KX2 batt

[John Oppenheimer]

Using the DISP voltage, using internal battery, receive is 11.7V and 10W
in TUNE is 10.8V. a drop of 0.9V. The receive drop is a tenth or two, or
round down to a 1V total voltage drop during 10W transmit. The minimum
battery voltage would then be 11V or 3.67V per cell. Looking at
representative discharge curves, 3.67V, is consistent with a 50% discharge.

John KN5L

On 10/16/2016 08:01 AM, Chip Stratton wrote:
> The unloaded voltage of your pack, and the number of amp-hours used are
> consistent with each other, you are about half-way through the usable
> amp-hours of the battery, which has a 2.3 amp-hour rated capacity. Not sure
> exactly what to expect about the voltage drop under load, but I am not
> surprised by it, it would suggest the battery supply has about a 350
> milliohm resistance which again is not surprising.
> 
> I think all is normal with your battery and rig. I'm sure someone else on
> the list with confirm or deny me!
> 
> They could have used Panasonic 3.2 amp-hour 18650 cells in the battery pack
> with no increase in size for longer operating time, but maybe it was a
> weight isssue?
> 
> Chip
> AE5KA
> 
> On Sun, Oct 16, 2016 at 8:31 AM, Howard Sherer  wrote:
> 
>> I have been running my KX2 with the Elecraft supplied batt pack for the
>> past two weeks and have a question for others using the same. I can run the
>> KX2 at 10W only till I have used 1.12 AH of the batt capacity and its key
>> up V=11.0 and key down is 10.3. At this time I can only run the KX2 at 5W.
>>
>> I was expecting that I would be able to run the KX2 at 10W for a longer
>> period. I have repeated this through 4 recharge cycles and the results ar
>> the same. Is my batt pack showing reduced performance?
>>
>> Overall I am very pleased with the performance of the KX2
>>
>> Howard AE3T
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Re: [Elecraft] K2 Poor sensitivity

[John Oppenheimer]

Hi Paul,

There is a procedure for estimating MDS documented in the XG3 manual,
the "Measuring Receiver Sensitivity" section:
http://www.elecraft.com/manual/E740154%20XG3%20Owner%27s%20Manual%20Rev%20D2%20-%20ECO%2001887.pdf

I've performed this test and found my K2 to have a reasonable match.

John KN5L

On 09/27/2016 05:38 AM, Radiobeamer wrote:
> I noticed that the S meter was not moving very much so I thought to
> check the sensitivity.  According to the spec we should have a sensitivity
> (MDS) of something like -130dBm without the preamp and -135dBm with the
> preamp.  I have an HP signal generator and, without being too precise about
> MDS etc,
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[Elecraft] KX2 KXIO2 Time Hack

[John Oppenheimer]

Hi Wayne,

Sure would be nice if while in TIME MENU, pushing "3" would set seconds
to zero. This would make it much easier to hack to WWV. Or to maintain
backwards compatibility, program "4" as a seconds hack button.

John KN5L
KX2 #80
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Re: [Elecraft] KX3 Antenna Tuner Settings

[John Oppenheimer]

Here is Wayne's email referencing the KX3 ATU L and C values:

On 08/02/2012 12:29 PM, Wayne Burdick wrote:
> We're still working on getting the schematics formatted for
> publication. Meanwhile, here are the approximate L and C values:
>
>   L:   8, 4, 2, 1, 0.5, 0.25, 0.12, and 0.06 uH
>
>   C:   1360, 680, 330, 164, 82, 39, 18, 10 pF


John KN5L

On 07/25/2016 04:36 PM, John Oppenheimer wrote:
> The command is:
> AK (ATU Network Values; KX3/KX2 only, GET only)
> 
> Programmer's Reference Page 3.
> 
> The KX3 L and C values can be found from the schematic. Wayne sent an
> email some years ago with the list of L can C values.
> 
> I don't believe that the KX2 L and C values have been published.
> 
> John KN5L
> 
> On 07/25/2016 04:12 PM, thelastdb wrote:
>> Hi Bob,
>> Which tab is that under?
>> Myron WVØHPrinted on Recycled Data  Original message From: 
>> Bob N3MNT <b...@hogbytes.com> Date: 7/25/2016  3:05 PM  (GMT-07:00) To: 
>> elecraft@mailman.qth.net Subject: Re: [Elecraft] KX3 Antenna Tuner Settings 
>> Connect the KX3 utility it will show you the exact values the tuner has
>> chosen to match the antenna.
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Re: [Elecraft] KX3 Antenna Tuner Settings

[John Oppenheimer]

The command is:
AK (ATU Network Values; KX3/KX2 only, GET only)

Programmer's Reference Page 3.

The KX3 L and C values can be found from the schematic. Wayne sent an
email some years ago with the list of L can C values.

I don't believe that the KX2 L and C values have been published.

John KN5L

On 07/25/2016 04:12 PM, thelastdb wrote:
> Hi Bob,
> Which tab is that under?
> Myron WVØHPrinted on Recycled Data  Original message From: 
> Bob N3MNT  Date: 7/25/2016  3:05 PM  (GMT-07:00) To: 
> elecraft@mailman.qth.net Subject: Re: [Elecraft] KX3 Antenna Tuner Settings 
> Connect the KX3 utility it will show you the exact values the tuner has
> chosen to match the antenna.
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Re: [Elecraft] Linear PS Recommendations

[John Oppenheimer]

Hi All,

Here is a link to a schematic for the 3/4 A power supplies with the
added parts for external voltage protection:

http://www.ameradio.com/doc/Astron%20RS-3A,%20RS-4A%20schematic.pdf

John KN5L

On 07/21/2016 07:41 AM, Myron Schaffer wrote:
> It used to be that waythe RS linear models could not tolerate external 
> voltage present when unpowered, not anymore. Astron has incorporated 
> back-voltage protection through incorporation of some diodes installed in key 
> locations to prevent this.
> 
> You can verify if your supply has this modification by looking at the circuit 
> board and see a 1N4001 type diode soldered across 2-pins (can't remember 
> which ones off the top of my head) of the IC voltage regulator LM-723 chip 
> and others hung in various places to protect the pass transistor as well. 
> Usually soldered to the solder side of the circuit board so they are easy to 
> spot. I can't remember is there were some small capacitors added as well.
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[Elecraft] KX2 FIL display change suggestion

[John Oppenheimer]

Can the FIL default display "FIL ADJ" be replaced with the current
setting? This change will allow viewing the BW without the need to tune
the BW.

Using MCU 2.66 / DSP 1.48

John KN5L
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Re: [Elecraft] Suggested KX3 "upgrade"

[John Oppenheimer]

My general operating style is to use a CW memory REPEAT for sending CQ,
both at home and during field operations.

I sure would be nice to end the memory with a tap of the key and not
send an element. Both my new KX2 and KX3.

John KN5L

On 05/30/2016 06:27 PM, Jim Rodenkirch wrote:
> Could sumpin' be done, firmware wise, to let us hit the the key without
> sending the dit or dah?
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[Elecraft] KX2 with Begali Adventurer Mono

[John Oppenheimer]

Thank you Ed, this is the answer I've been waiting for:

John KN5L

On 05/20/2016 11:10 PM, Ed Muns wrote:
> I have been using a Begali Adventurer Mono on my KX2 SN 20 for several weeks
> now with no problem.  The screws look short enough and are not anywhere
> close to the PCB.
> 
> This morning (Friday) before the Dayton vendor displays opened, I had Wayne
> look at my paddle and he verified that the screws were short enough.
> 
> Ed W0YK
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Re: [Elecraft] W1

[John Oppenheimer]

I performed some additional research, Johnny, VR2XMC, measured TP1 V at
4.82 back in December 2006. Maybe the 4.5 is a typo and should be 4.8:
http://elecraft.365791.n2.nabble.com/some-questions-of-W1-td442330.html

John KN5L

On 12/31/2015 06:22 AM, John Oppenheimer wrote:
> Hi Ed.
> 
> The W1 DC voltage calibration resulted with incorrect reading with my
> W1. My hunch is that components have changed since Elecraft established
> the TP1 DC calibration voltage almost a decade ago.
> 
> I have a KX3F with unchanged factory power calibration. Based on
> comments from Wayne, the KX3 is calibrated at 7.0 watts.
> 
> My W1 TP1 voltage is 4.812 using a Fluke 87V
> 
> Setting up a test bench with KX3 -> W1 -> DL1
> 
> Using W1 Utility to display W1 power:
> http://www.elecraft.com/software/W1/elecraft_w1_software.htm
> 
> TP1 V = 4.812
> KX3 power = 7.0 W
> W1 power = 7.02
> DL1 V = 12.91 = 6.93 watts
> 
> The W1 20 dB directional coupler does absorb power, at 7 watts, the
> directional coupler will absorb 0.07 watts. Adding 0.07 to the DL1
> measurements equals 7.00 watts.
> 
> John KN5L
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Re: [Elecraft] W1

[John Oppenheimer]

Hi Ed.

The W1 DC voltage calibration resulted with incorrect reading with my
W1. My hunch is that components have changed since Elecraft established
the TP1 DC calibration voltage almost a decade ago.

I have a KX3F with unchanged factory power calibration. Based on
comments from Wayne, the KX3 is calibrated at 7.0 watts.

My W1 TP1 voltage is 4.812 using a Fluke 87V

Setting up a test bench with KX3 -> W1 -> DL1

Using W1 Utility to display W1 power:
http://www.elecraft.com/software/W1/elecraft_w1_software.htm

TP1 V = 4.812
KX3 power = 7.0 W
W1 power = 7.02
DL1 V = 12.91 = 6.93 watts

The W1 20 dB directional coupler does absorb power, at 7 watts, the
directional coupler will absorb 0.07 watts. Adding 0.07 to the DL1
measurements equals 7.00 watts.

John KN5L
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