Re: [Elecraft] Correct Link..

[Kurt Pawlikowski]

David,

   As I don't have a K3 (), I was wondering if you might post a 
screen capture of your "baby" in action. {'-)


   Regards,

   kurtt

   Kurt Pawlikowski, AKA WB9FMC
   The Pinrod Corporation
   [EMAIL PROTECTED]
   (773) 284-9500
   http://pinrod.com

David Fleming wrote:

Sorry. Here's the correct link..

http://sight.net/K3Meter

David, W4SMT

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RE: [Elecraft] So you want an analog s-meter for the K3?

[Joe Subich, W4TV]

David, 

I'd suggest some averaging ... perhaps five or 10 sample 
log weighted moving average ... and recommend converting 
from BG; to SM; polling since the BG; scale is truncated 
if CWT is selected in CW or data modes. 

73, 

   ... Joe, W4TV 
 


> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of David Fleming
> Sent: Sunday, November 02, 2008 12:10 AM
> To: elecraft@mailman.qth.net
> Subject: [Elecraft] So you want an analog s-meter for the K3?
> 
> 
> Here you go...
> 
> http:/sight.net/K3Meter
> 
> And there's a Windows version too! :)
> 
> Enjoy!
> 
> David, W4SMT
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[Elecraft] So you want an analog s-meter for the K3?

[Don Rasmussen]

Fabulous David !

Now add some dampening for the movement and it will be perfect, it's a bit 
jumpy at present. Love the meter face. 


 

[Elecraft] So you want an analog s-meter for the K3?
David Fleming dflem at yahoo.com 
Sat Nov 1 23:09:45 EST 2008 

Previous message: [Elecraft] Elecraft CW Net NON-Announcement 
Next message: [Elecraft] Correct Link.. 
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] 



Here you go...

http:/sight.net/K3Meter

And there's a Windows version too! :)

Enjoy!

David, W4SMT


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[Elecraft] Correct Link..

[David Fleming]

Sorry. Here's the correct link..

http://sight.net/K3Meter

David, W4SMT

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[Elecraft] So you want an analog s-meter for the K3?

[David Fleming]

Here you go...

http:/sight.net/K3Meter

And there's a Windows version too! :)

Enjoy!

David, W4SMT
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[Elecraft] Elecraft CW Net NON-Announcement

[Kevin Rock]

Good Evening,
   The Elecraft CW Net will NOT be run tomorrow due to large numbers of avid 
(rabid?) contesters banging away at their keyboards :)  I am sure they will all 
be just a little crazy by this point in the contest so I don't wish to goad 
them into untoward behaviors.  Next week the nets will be back.  The time will 
change too.  Not the local time but the Zulu time.  As usual I will probably 
get confused but with a week to resolve this issue I may just get it right this 
time.  So same local time (that's the easy part).
   See you all next week,
  Kevin.  KD5ONS


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Re: [Elecraft] Using K3 with AMP

[Don Wilhelm]

George,

What K3 jack are you connecting the amp to?  You should be connecting to 
the KEYOUT jack.  If you have connected to the K3 PTT input instead, I 
could understand that you might have difficulties like you describe.


73,
Don W3FPR

K4GM-George wrote:
For several years I keyed my Dentron Clipperton L amp from the jack on 
my Pro II. I did not use any buffer and it always worked fine because 
the voltage/current being keyed are w/i limitations of the Pro II.  
Without powering up the AMP I ran a cable from the AMP to the jack on 
the K3 I just received.  I noticed that WITHOUT AC power to the amp 
when I moved the standby switch to operate the K3 PTT was keyed and 
the rig put out normal power.  This is w/o the AMP being ON.  Any 
thoughts from anyone? I do have an AMPKEYER available to use between 
the units but thought I could key the AMP  directly. Why would my 
STANDY/OPERATE switch on the amp operate as a PTT switch?  Do I need 
to set a parameter in the K3?  Of course all equipment share a common 
ground connection.




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Re: [Elecraft] [K2] Excessive PSK IMD with new K2/100

[Don Wilhelm]

David,

The KPA100 can be coupling back into the KSB2 option.
Remove the right side panel and tuck the ribbon cable and speaker cable 
up into the space at the top of the KPA100 instead of letting it dangle 
near the KSB2 board.


I will not guarantee that it will help, but it often makes a difference 
on SSB, and can also help on data modes.


73,
Don W3FPR

dberkley wrote:

Just built a KPA100 for my K2 S/N 6274.  When originally running PSK on the
barefoot K2 had no problem achieving IMD around -30 dB (measured with
PSKmeter).  The K2 had a KAT2 tuner which was removed, and replaced by an
external autotuner when the KPA100 was installed.

With the new KPA100 in place I can't get the IMD below about -24 dB and it
seems to be independent of power setting or actual output power (including
bypass mode at 5 watts which is where I set the original K2) and remarkably
independent of audio drive, which wasn't true with original K2.  There is a
broad minimum in the IMD when the ALC barely flickers on the 3rd bar. 
Optimal performance is on 20m but there is little difference on other bands

(when the audio is adjusted).

Any thoughts on what has changed?  Is there any obvious way to improve IMD,
although I guess > -20 dB is in the barely acceptable range?
  


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[Elecraft] Using K3 with AMP

[K4GM-George]

For several years I keyed my Dentron Clipperton L amp from the jack on 
my Pro II. I did not use any buffer and it always worked fine because 
the voltage/current being keyed are w/i limitations of the Pro II.  
Without powering up the AMP I ran a cable from the AMP to the jack on 
the K3 I just received.  I noticed that WITHOUT AC power to the amp when 
I moved the standby switch to operate the K3 PTT was keyed and the rig 
put out normal power.  This is w/o the AMP being ON.  Any thoughts from 
anyone? I do have an AMPKEYER available to use between the units but 
thought I could key the AMP  directly. Why would my STANDY/OPERATE 
switch on the amp operate as a PTT switch?  Do I need to set a parameter 
in the K3?  Of course all equipment share a common ground connection.


73, K4GM George
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[Elecraft] [K2] Excessive PSK IMD with new K2/100

[dberkley]

Just built a KPA100 for my K2 S/N 6274.  When originally running PSK on the
barefoot K2 had no problem achieving IMD around -30 dB (measured with
PSKmeter).  The K2 had a KAT2 tuner which was removed, and replaced by an
external autotuner when the KPA100 was installed.

With the new KPA100 in place I can't get the IMD below about -24 dB and it
seems to be independent of power setting or actual output power (including
bypass mode at 5 watts which is where I set the original K2) and remarkably
independent of audio drive, which wasn't true with original K2.  There is a
broad minimum in the IMD when the ALC barely flickers on the 3rd bar. 
Optimal performance is on 20m but there is little difference on other bands
(when the audio is adjusted).

Any thoughts on what has changed?  Is there any obvious way to improve IMD,
although I guess > -20 dB is in the barely acceptable range?

73, David
K2MUN
-- 
View this message in context: 
http://n2.nabble.com/-K2--Excessive-PSK-IMD-with-new-K2-100-tp1444180p1444180.html
Sent from the [K2] mailing list archive at Nabble.com.

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RE: [Elecraft] K3 Feedback

[Dr. James C. Garland]

Lynn,
Your problem parallels mine exactly. Although your Astron switching supply
only powers the K3, the Astron internally jumpers its negative voltage
terminal to the chassis and AC ground. If you don't want to rewire the K3's
microphone connector, or jumper an intenral RF choke, as some have suggested
on the List, then you'll need to take the cover off your Astron and remove
the ground jumper from the negative terminal. I checked my 30Amp Astron
(Model SS-30M), and the jumper is easily removed. It goes from the negative
voltage terminal to a screw on the chassis.

I'll be interested in what the folks at Elecraft tell you about the audio
distortion problem. I doubt that the filter change will affect it, though
the 2.8 kHz filter is a very nice filter.

73,
Jim W8ZR

> -Original Message-
> From: [EMAIL PROTECTED] [mailto:elecraft-
> [EMAIL PROTECTED] On Behalf Of Lynn Lamb, W4NL
> Sent: Saturday, November 01, 2008 6:43 PM
> To: Elecraft Reflector
> Subject: [Elecraft] K3 Feedback
> 
> The exchange here on the reflector is enjoyable and very much a good
> source
> of information.   I have no answers for the feedback problem with the K3
> but
> let me offer my situation.
> 
> There is feedback in my audio using the NCS Switcher and I have discussed
> it
> with Doug of NCS.   There is no feedback using 5 other rigs.. the Orion,
> FT-950, K2, Omni VII, and TS-480.
> 
> There is no feedback when using a mic directly in the front of the K3..
> works great.  I've not tried the rear mic connection at all.
> 
> The power supply has nothing hooked up to it but the K3.  It's an Astron
> 25
> amp switching supply.
> 
> Many things I've tried.. the normal things mentioned here on the 'net'.
> Nothing helped.
> 
> Elecraft has my K3 now looking into this problem, calibrating and changing
> the 2.7 filter with a 2.8.  I noted the 2.7 was not an enclosed filter and
> the 2.8 ...or the other 8 pole filters I installed are enclosed.  I've ask
> it be replaced with the 2.8.  Will it help the feedback problem (?), I
> don't
> have a clue, but it can't hurt.
> 
> I feel Elecraft will find the problem soon.  Any group of folks who could
> design and build a box of 8.5 lbs of this caliber can find and fix this
> problem.  No question.
> 
> Thanks for all the ideas and may I say there IS comfort in numbers
> relative
> to this issue, hi.
> 
> 73, lynn W4NL
> 
> 
> www.SEDCO.Homestead.com
> 
> 
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[Elecraft] K3 sweepstakes this weekend

[Don Rasmussen]

K3 #272 was on the air for it's first ARRL SS this afternoon, on 20m and what a 
treat. This contest and the CQWWCW are the two contests that I dream of, even 
though I never post my logs. It's just a great time to stress test the 
transceiver and to get a real idea what the bands are doing since there is 
always someone on the band. Don't miss the opportunity, I did some more A/B 
tests and I've not had a radio in the past that was not the loser in at least 
some condition. So far, K3 has always been the best, or has been able to be 
dialed in to make it that way. Very nice. 
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[Elecraft] K3 Feedback

[Lynn Lamb, W4NL]

The exchange here on the reflector is enjoyable and very much a good source 
of information.   I have no answers for the feedback problem with the K3 but 
let me offer my situation.


There is feedback in my audio using the NCS Switcher and I have discussed it 
with Doug of NCS.   There is no feedback using 5 other rigs.. the Orion, 
FT-950, K2, Omni VII, and TS-480.


There is no feedback when using a mic directly in the front of the K3.. 
works great.  I've not tried the rear mic connection at all.


The power supply has nothing hooked up to it but the K3.  It's an Astron 25 
amp switching supply.


Many things I've tried.. the normal things mentioned here on the 'net'. 
Nothing helped.


Elecraft has my K3 now looking into this problem, calibrating and changing 
the 2.7 filter with a 2.8.  I noted the 2.7 was not an enclosed filter and 
the 2.8 ...or the other 8 pole filters I installed are enclosed.  I've ask 
it be replaced with the 2.8.  Will it help the feedback problem (?), I don't 
have a clue, but it can't hurt.


I feel Elecraft will find the problem soon.  Any group of folks who could 
design and build a box of 8.5 lbs of this caliber can find and fix this 
problem.  No question.


Thanks for all the ideas and may I say there IS comfort in numbers relative 
to this issue, hi.


73, lynn W4NL


www.SEDCO.Homestead.com 



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Re: [Elecraft] K3 RF Feedback Problem

[Paul Christensen]

"I know it is good engineering practice often to isolate internal 
circuitry from chassis ground. Lab quality signal generators, for example, 
usually tie the shell of their RF output connector to the chassis via a 
(typically) 100 ohm resistor..."


Moreover, designers of instrumentation-grade circuitry often tie multiple 
returns to one common chassis ground.  I know of one test equipment product 
that utilizes five separate return path references to ground (e.g., digital 
ground, analog ground, power supply ground, control systems ground, etc.), 
but in each case, the return path currents are controlled and reasonably 
isolated for each of the stated purposes.  Nevertheless, each of the five 
returns circuits in this example are tied to exactly one common chassis 
point.  But the current for the respective circuits circulate among their 
own returns and not with others.  They share just one low-impedance common 
point.  By contrast, ground loops exist in other equipment where one common 
return is used with multiple circuit bonding points and various DC, AF, and 
RF current are allowed to share and flow past sensitive devices.


For example, if there's a high current return path in a control circuit 
(e.g., open collector to a solenoid), then the ground returns on a sensitive 
3-stage-input instrumentation op-amp circuit (e.g., a high-gain mic pre-amp) 
should not be sensitive to the current demands of the solenoid.  The 
addition of a 100-ohm resistor in your example may be one such use of 
limiting return current on  circuit paths *within* a piece of equipment.


But what is occurring with the K3's mic returns is a total isolation of a 
common, grounded return path of the front and rear panel mic jacks at RF. 
Yes, from D.C. through audio frequencies the return path is unimpeded as a 
result of L4 and L7.  But in the presence of RF, at some frequency between 
AF and RF, the ground reference looking into the K3 mic connectors is 
completely lost.


"Perhaps it has something to do with using balanced line audio sources. 
Minimizing ground loops can be a headache when one has multiple audio 
devices, powered by different power supplies."


Even in balanced audio systems, the same rules apply.  Had the K3 been 
designed with a truly balanced, 3-stage instrumentation input for its mic 
pre-amp, the inclusion of L4 and L7 on the shielded return paths would have 
the same effect.  The saving grace in an instrumentation-input circuit (or 
in the alternative, an audio transformer input) is the inherently large 
common-mode rejection ratio (CMRR) across a very broad frequency span that 
limits the presence of RF on a twisted-pair audio line, even in the total 
absence of the cable shielding.  For nearly 100 years, the Bell System and 
its progeny have used unshielded twisted-pair balanced audio systems in the 
presence of outrageously-high RF fields with no measurable detriment to 
performance in many instances.


Paul, W9AC



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[Elecraft] K3 max power out 63W?

[Rob May]

I dont' know when it happened, but I can no longer get full power out of my K3 
(s/n 1417 FW 2.58 DSP 1.94).  Using the tune control, power out will not go 
above 63 watts.  I can do the TXGN calibration at 5W and 50W with no problem.  
But if I turn up the power, the output never goes above 63W, i.e. if I dial in 
50, I get 50W, if I dial in 63, I get 63W, if I dial in 75, I get 63W, if I 
dial in 100 or 120, I get 63W.  It used to work ok.  This is all into a dummy 
load with an indicated SWR of 1.1-1.  What could have happened?  I've tried 
going back to FW 2.45, but the problem still exists.  Any help would be 
appreciated.
Rob
NV5E

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Re: [Elecraft] K3 RF Feedback Problem

[Don Wilhelm]

Paul,

Although the inductors may be at fault (and IMHO should be jumpered 
out), there are other considerations that enter into the picture. The 
most predominate is the power supply. If external boxes have independent 
powering, that can often cause problems because the power supply common 
is not at the same potential for all the supplies. In addition, most 
Astron power supplies (and others too), connect the negative output 
terminal back the the AC safety ground which can cause ground currents 
to flow and give rise to many 'strange happenings'. A good check for 
power supply grounding problems is to temporarily run the K3 from a 12 
volt battery (an automotive type will do for the K3/100).


73,
Don W3FPR

Paul Christensen wrote:

Jim,
This may, or may not be the root cause of your RFI problem, but it is 
important to note that the K3 elevates the ground potential on both 
the front and rear panel MIC connectors. This is not a trivial issue. 
L7 is a 100 uH choke that isolates the ring of the rear panel TRS 
connector (J20) from chassis ground.
In the same manner, L4 (another 100 uH) RFC) isolates ground pins 7 & 
8 on the front panel MIC jack from chassis ground. The net effect of 
these chokes results in an "ungrounding" of the MIC inputs.. The 
addition of the chokes is something completely opposite of what is 
required in this part of the circuit.
When conducting other K3 audio mods, I went in and removed both L4 and 
L7, and jumpered the solder pads with 24 AWG buss wire.

In my case, RFI problems 100% solved.
Paul, W9AC

- Original Message -
*From:* Dr. James C. Garland 
*To:* elecraft@mailman.qth.net 
*Sent:* Saturday, November 01, 2008 9:57 AM
*Subject:* [Elecraft] K3 RF Feedback Problem

Gang,

I’m pulling my hair out over an RF feedback problem with my
K3/100, and wonder if anybody has any ideas? I use an external
station controller that switches key, microphone, CAT, line
in/out, etc. between different rigs. The microphone audio connects
to the K3’s rear panel microphone jack and when the K3’s power
exceeds about 15W (in SSB), the audio becomes greatly istorted. It
does this when all the other cables to the K3 (except the
microphone and power cord) are unplugged. It also does it when the
audio is fed to the K3 via the rear Line In jack. Everything in my
station is well-grounded. Here are some things I’ve noticed:

1. The feedback still occurs when a military-type completely
shielded 100W dummy load is screwed directly to the K3’s antenna
port. This suggests the RF from the K3 is getting into the audio
line from some other source than radiation from the coax cables in
the station, most likely the 12V power cord. To support this
conjecture, I also notice that the feedback threshold (15W) is not
changed when the K3 drives a linear amplifier.

2. I normally use a 30A Kepco 12V power supply to run the K3 and
my other station accessories. The RF feedback problem is improved
but not entirely eliminated if I use a separate 12V supply for the
K3. A common mode choke on the 12V line doesn’t appear to make any
difference.

3. I can see some modulation-induced fluctuationss on the 12V line
with an oscilloscope that increase with the K3’s power setting. I
haven’t looked at these fluctuations closely enough yet to know
whether it’s RF noise or just audio—frequency fluctuations caused
by the K3’s modulating current draw from the power supply.

To summarize, my conclusions so far are that (1) the 12V power
cord is a source of RF leakage from the K3, even though the K3 has
a filter at its 12V power connector to minimize this leakage; and
(2) The audio/DSP circuitry in the K3 is very sensitive to RF –
much more so than other transceivers in my station. (I’ve not had
this problem with other rigs.)

Because of this RF sensitivity, one evidently has to be very
careful when hooking accessories to the K3. The front panel
microphone jack is (to me) wired in a curious way, with the Mic
ground and PTT ground (shield) connections floating above the K3’s
chassis with a 100uH rf choke. Similarly, both the “hot” and
“shield” side of the rear panel mic input jack has series 100uH rf
chokes, which isolate the input from chassis ground.

The problem with this arrangement is that most accessories that
would connect to the rear panel audio input jacks have
single-ended outputs, with a shielded cable that is directly tied
to chassis ground at the accessory end of the cable. Thus, unless
one is very careful, it is easy to have a situtation where the
signal grounds in the audio circuitry of the K3 can fluctuate with
respect to the K3’s chassis ground, and this may be the source of
the RF feedback sensitivity.

Unfortunately, I can’t figure out 

RE: [Elecraft] K3 RF Feedback Problem

[Joe Subich, W4TV]

Jim, 

> When I floated the negative return of the 12V 
> supply, the distortion in the audio disappeared, so long as 
> no other accessories were powered by the same 12V power 
> supply. I measured about 200 mV p-p voltage fluctuations 
> between the negative supply voltage and the chassis of the 
> K3, when I talked into the K3 at 100W output.

When initially trying to resolve the issues with microHAM 
interfaces and the K3, I also thought this was the problem. 
Several users went to the extent of powering their radios 
from batteries in an attempt to prevent return currents from 
finding their way back to the power supply via the common 
chassis grounds on the accessory (microHAM) equipment. 

While is was successful in some cases, the only universal cure 
was fixing the "pin 1 problem" with the front panel microphone 
connector. 

> I know it is good engineering practice often to isolate 
> internal circuitry from chassis ground. Lab quality signal 
> generators, for example, usually tie the shell of their RF 
> output connector to the chassis via a (typically) 100 ohm 
> resistor. This isolation minimizes ground loop problems and 
> current imbalance in the coax cable. So I don't fault 
> Elecraft for doing this with the K3. 

The case of the K3 is just the opposite of what you describe. 
The internal circuitry is tied to the chassis but the external 
circuits are "floated" on the RF chokes in the return leads.  
Specifically, the rear panel PTT/Foot switch return, front and 
rear panel mic returns, the common on the ACC connector and the 
RS-232 return are all go through RF chokes before reaching the 
circuit common AND chassis ground. 

The cause of the problem is the use of a common choke for the 
front panel PTT and mic returns.  When external interfaces 
connect the PTT return to the chassis that 70 mV of ripple 
appears at the top of the common RF choke (L7) - here's the 
problem - effectively in series with the microphone signal!  
Anything that eliminates the common impedance (think 
"modulation choke") - including moving the PTT return 
connection from pin 8 to the shell (chassis) of the of the 
front panel mic jack or replacing L7 with a jumper - resolves 
the problem by eliminating the place the RF gets into the 
system.   

73, 

   ... Joe, W4TV 
 



> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of 4CX250B
> Sent: Saturday, November 01, 2008 5:02 PM
> To: elecraft@mailman.qth.net
> Subject: RE: [Elecraft] K3 RF Feedback Problem
> 
> 
> Thanks very much to Joe W4TV and  Ian  GM3SEK  for their 
> helpful comments.Here's what I've learned.
> 
> 1. RF leakage from the K3 into the 12V power cord does not 
> appear to be a problem, as Ian surmised. Furthermore, as Ian 
> also noted "If the PS is allowed to float and the common 
> negative return for all the accessories is moved very close 
> to the K3, that might solve the problems."  This was largely 
> correct. When I floated the negative return of the 12V 
> supply, the distortion in the audio disappeared, so long as 
> no other accessories were powered by the same 12V power 
> supply. I measured about 200 mV p-p voltage fluctuations 
> between the negative supply voltage and the chassis of the 
> K3, when I talked into the K3 at 100W output.
> 
> 2. 12V accessories ordinarily have their negative power 
> terminal tied to their chassis ground. This is true of all 
> the accessories in my station, including a homebrew keyer, an 
> Alpha 4510 wattmeter, an EQ Plus audio compander, a 60 stereo 
> amp used to drive bookshelf speakers,and my homebrew station 
> controller. When I connected ANY of these to the same 12V 
> line powering the K3, the distortion returned.  Evidently, 
> the K3's internal circuitry really like to have its local 
> circuit ground isolated from its chassis.
> 
> 3. A complicating factor is that I use a RIGrunner 12V 
> distribution panel (model 4010S) to distribute 12V around to 
> all the items in the station using standard Powerpole 
> connectors.  I discovered that the  frame of the RIGrunner is 
> internally connected to all its  negative (black) Powerpole 
> connectors, making it difficult to run an isolated negative 
> return on my 12V line.
> 
> My fix for all of these is to use two 12V power supplies: a 
> 30A Kepco supply with floating outputs for the K3, and a 6 
> Amp Lambda supply to power the accessories, via the RIGrunner 
> distribution panel. No other devices in my station, other 
> than the K3, have any problem with the negative 12V line tied 
> to their chassis.
> 
> I know it is good engineering practice often to isolate 
> internal circuitry from chassis ground. Lab quality signal 
> generators, for example, usually tie the shell of their RF 
> output connector to the chassis via a (typically) 100 ohm 
> resistor. This isolation minimizes ground loop problems and 
> current imbalance in the coax cable. So I don't fault 
> Elecraft for doing this with t

Re: [Elecraft] K3 default data mode

[Bob Thompson - N9SF]

Dave,
It was puzzling.  I had the same situation.  Because I often
use the M>V tap and a number key to change bands, I found that I was
resetting my data mode to AFSK A.
When a frequency is stored in a memory regardless of the mode, SSB, CW,
or data, the data mode in play at the time is stored as
well.
So, I went through all the "number key" memories and stored
them all again.  Even though the mode stored is CW, I went over to
the DATA MD and made sure it was FSK D.  Then I switched back to CW
and stored it, V>M and a number key.
It is a bit confusing, but I hope this helps.
73,
Bob - N9SF

At 02:10 PM 11/1/2008, you wrote:
Every time I switch to data
mode, the K3 comes up in AFSK A, which I never use. Is there a way to
have it default to FSK D?
Dave Hachadorian, K6LL
Yuma, AZ












. 
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[Elecraft] K2 40 Meter Problem

[Dave Agsten]

My brother is working on an intermittent problem with 40 meter receive. It 
started out with 40 meters going almost dead. Tapping on the chassis would 
return the receive function to normal for awhile. He just opened up the radio 
and tried to track down the problem. The KXV60 board, when tapped, would, make 
the problem disappear. He removed the board and narrowed the problem down to 
the 40 meter bandpass filter area. He looked at the solder joints and did not 
see any that looked bad. He's going to look those over again with more light 
and a bigger magnifying glass. Then, if he doesn't find anything, he will 
reheat all of the solder joints. He says that it seems most likely that the 
problem is around L1 and L2 since when he taps in that area, the problem goes 
away and then comes back. It may be the transformers, a relay or some other 
component. Hopefully, he'll find a bad solder joint or reheating them all will 
solve the problem. I'm wondering if anyone has
 possible solutions, a way to narrow the problem down further or any 
suggestions.

Tnx es 73,
Dave N8AG


  
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RE: [Elecraft] K3 RF Feedback Problem

[4CX250B]

Thanks very much to Joe W4TV and  Ian  GM3SEK  for their helpful 
comments.Here's what I've learned.

1. RF leakage from the K3 into the 12V power cord does not appear to be a 
problem, as Ian surmised. Furthermore, as Ian also noted "If the PS is allowed 
to float and the common negative return for all the accessories is moved very 
close to the K3, that might solve the problems."  This was largely correct. 
When I floated the negative return of the 12V supply, the distortion in the 
audio disappeared, so long as no other accessories were powered by the same 12V 
power supply. I measured about 200 mV p-p voltage fluctuations between the 
negative supply voltage and the chassis of the K3, when I talked into the K3 at 
100W output.

2. 12V accessories ordinarily have their negative power terminal tied to their 
chassis ground. This is true of all the accessories in my station, including a 
homebrew keyer, an Alpha 4510 wattmeter, an EQ Plus audio compander, a 60 
stereo amp used to drive bookshelf speakers,and my homebrew station controller. 
When I connected ANY of these to the same 12V line powering the K3, the 
distortion returned.  Evidently, the K3's internal circuitry really like to 
have its local circuit ground isolated from its chassis.

3. A complicating factor is that I use a RIGrunner 12V distribution panel 
(model 4010S) to distribute 12V around to all the items in the station using 
standard Powerpole connectors.  I discovered that the  frame of the RIGrunner 
is internally connected to all its  negative (black) Powerpole connectors, 
making it difficult to run an isolated negative return on my 12V line.

My fix for all of these is to use two 12V power supplies: a 30A Kepco supply 
with floating outputs for the K3, and a 6 Amp Lambda supply to power the 
accessories, via the RIGrunner distribution panel. No other devices in my 
station, other than the K3, have any problem with the negative 12V line tied to 
their chassis.

I know it is good engineering practice often to isolate internal circuitry from 
chassis ground. Lab quality signal generators, for example, usually tie the 
shell of their RF output connector to the chassis via a (typically) 100 ohm 
resistor. This isolation minimizes ground loop problems and current imbalance 
in the coax cable. So I don't fault Elecraft for doing this with the K3. The 
problem is that doing can introduce compatibility problems with otherstation  
instruments, as in my case.

Thanks again to all for your suggestions and commens.

73,

Jim W8ZR
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Re: [Elecraft] K3 default data mode

[Julian, G4ILO]

Dave Hachadorian wrote:
> 
> Every time I switch to data mode, the K3 comes up in AFSK A, 
> which I never use. Is there a way to have it default to FSK 
> D?
> 
Mine comes up in whatever data mode I last used on that band. I don't know
why yours should behave differently.

-
Julian, G4ILO. K2 #392  K3 #222.
http://www.g4ilo.com/ G4ILO's Shack   http://www.ham-directory.com/ Ham
Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 
-- 
View this message in context: 
http://n2.nabble.com/K3-default-data-mode-tp1442811p1443304.html
Sent from the Elecraft mailing list archive at Nabble.com.

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[Elecraft] K3 kit #1244 ERR TXG

[Tony Morgan]

Trying to do the transmitter gain alignment (5 watt)
Getting the ERR TXG on all bands.
KPA3 not installed.
Stock 2.7 filter installed only.
All modes set to use this filter on xmit using K3 utility.
Have run synth alignment  & ref osc alignment several times.
All tmp cables are in correct locations with good connections.
Latest firmware 2.46 installed.
Looked through archives but no help so far.
Any ideas appreciated.

73,

Tony W7GO
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RE: [Elecraft] K3 RF Feedback Problem

[Joe Subich, W4TV]

Jamie, 

We had to modify all microHAM interface cables for the K3 
to move the PTT ground from Pin 8 to the shell of the Foster 
(mic) jack to avoid the "Pin 1 problem" caused by the common 
RF choke (L7) on the front panel board.  

I suspect your multi-switcher also connects PTT to pin 2/8, 
mic to 1/7 and a shield between the chassis of both units. 
Moving the PTT ground from pin 8 to the shell of the Foster 
plug (or connecting PTT ground to the chassis in the 
multi-switcher and leaving pin 8 open) should eliminate 
the problem completely.  

As W9AC reports, replacing L7 with a jumper seems to be the 
best solution but it requires disassembling the front panel 
of the radio.  A good "work around" is to install a jumper 
between pin 8 and the shell of your mic connector. 

73, 

   ... Joe, W4TV 
 


> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of James 
> C. Hall, MD
> Sent: Saturday, November 01, 2008 1:13 PM
> To: 'Dr. James C. Garland'; elecraft@mailman.qth.net
> Cc: 'W. Douglas McDowell'
> Subject: RE: [Elecraft] K3 RF Feedback Problem
> 
> 
> Hi Jim:
>  
> I'm wondering what external station controller you are using. 
> I'm using a NCS Multi-Switcher and I ran into very similar 
> issues. I certainly felt (as did Doug at NCS) that it was a 
> ground loop problem. I used transformer isolated mike cables 
> and found that it was NOT a ground problem. I can give you my 
> long details, but the bottom line is that the mike gain in 
> the Multi-Switcher (internal) needed to be driven a bit 
> higher than normal, and the mike gain on the K3 need to be 
> quite low (5 or 6) to avoid the 'growl' effect. I'm 
> forwarding this to Doug at NCS as he is quite interested in 
> what's going on that might be causing this.
>  
> 73, Jamie
> WB4YDL
>  
> 
> 
> 
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of Dr. 
> James C. Garland
> Sent: Saturday, November 01, 2008 8:57 AM
> To: elecraft@mailman.qth.net
> Subject: [Elecraft] K3 RF Feedback Problem
>  
> Gang,
>  
> I'm pulling my hair out over an RF feedback problem with my 
> K3/100, and wonder if anybody has any ideas? I use an 
> external station controller that switches key, microphone, 
> CAT, line in/out, etc. between different rigs.  The 
> microphone audio connects to the K3's rear panel microphone 
> jack and when the K3's power exceeds about 15W (in SSB), the 
> audio becomes greatly istorted. It does this when all the 
> other cables to the K3 (except the microphone and power cord) 
> are unplugged. It also does it when the audio is fed to the 
> K3 via the rear Line In jack. Everything in my station is 
> well-grounded. Here are some things I've noticed:
>  
> 1.  The feedback still occurs when a military-type completely 
> shielded 100W dummy load is screwed directly to the K3's 
> antenna port. This suggests the RF from the K3 is getting 
> into the audio line from some other source than radiation 
> from the coax cables in the station, most likely the 12V 
> power cord. To support this conjecture, I also notice that 
> the feedback threshold (15W) is not changed when the K3 
> drives a linear amplifier. 
>  
> 2.  I normally use a 30A Kepco 12V power supply to run the K3 
> and my other station accessories. The RF feedback problem is 
> improved but not entirely eliminated if I use a separate 12V 
> supply for the K3. A common mode choke on the 12V line 
> doesn't appear to make any difference. 
>  
> 3. I can see some modulation-induced fluctuationss on the 12V 
> line with an oscilloscope that increase with the K3's power 
> setting. I haven't looked at these fluctuations closely 
> enough yet to know whether it's RF noise or just 
> audio-frequency  fluctuations caused by the K3's modulating 
> current draw from the power supply.
>  
> To summarize, my conclusions so far are that (1) the 12V 
> power cord is a source of RF leakage from the K3,  even 
> though the K3 has a filter at its 12V power connector to 
> minimize this leakage; and (2) The audio/DSP circuitry in the 
> K3 is very sensitive to RF - much more so than other 
> transceivers in my station.  (I've not had this problem with 
> other rigs.) 
>  
> Because of this RF sensitivity, one evidently has to be very 
> careful  when hooking accessories to the K3. The front panel 
> microphone jack is (to me) wired in a curious way, with the 
> Mic ground and PTT ground (shield) connections floating above 
> the K3's chassis with a 100uH rf choke. Similarly, both the 
> "hot" and "shield" side of the rear panel mic input jack has 
> series 100uH rf chokes, which isolate the input from chassis ground. 
>  
> The problem with this arrangement is that most accessories 
> that would connect to the rear panel audio input jacks have 
> single-ended outputs, with a shielded cable that is directly 
> tied to chassis ground at the accessory end of the cable. 
> Thus, unless one is very careful, it is easy to have a 
> situtati

Re: [Elecraft] K3 RF Feedback Problem

[Ian White GM3SEK]

Dr. James C. Garland wrote:


Gang,

 

I?m pulling my hair out over an RF feedback problem with my K3/100,
and wonder if anybody has any ideas? I use an external station
controller that switches key, microphone, CAT, line in/out, etc. between
different rigs.  The microphone audio connects to the K3?s rear panel
microphone jack and when the K3?s power exceeds about 15W (in
SSB), the audio becomes greatly istorted. It does this when all the other
cables to the K3 (except the microphone and power cord) are
unplugged. It also does it when the audio is fed to the K3 via the rear
Line In jack. Everything in my station is well-grounded. Here are some
things I?ve noticed:

 

1.  The feedback still occurs when a military-type completely shielded
100W dummy load is screwed directly to the K3?s antenna port. This
suggests the RF from the K3 is getting into the audio line from some
other source than radiation from the coax cables in the station, most
likely the 12V power cord. To support this conjecture, I also notice that
the feedback threshold (15W) is not changed when the K3 drives a
linear amplifier.

 

2.  I normally use a 30A Kepco 12V power supply to run the K3 and my
other station accessories. The RF feedback problem is improved but
not entirely eliminated if I use a separate 12V supply for the K3. A
common mode choke on the 12V line doesn?t appear to make any
difference.


I just measured the common-mode RF current on the K3's 12V power cord at 
about 2mA at 7MHz, 100W into a dummy load. The background level was 1mA, 
most of which was coming *up* the line from the SMPS.


The meter consists of an RF current transformer made from a clamp-on 
ferrite core, feeding an AD8307 wide-range log detector. It responds to 
the total common-mode current from all sources combined, with a 
bandwidth from LF to several hundred MHz.


For perspective, about 1mA of assorted RF crud is a typical background 
level on computer and monitor cables, including the filtered mains input 
or DC output of a good-quality SMPS.  Common-mode currents are also 
installation-specific, because they depend on the impedance into which 
the current is flowing, so in real-life installations it's only 
justifiable to compare orders of magnitude (the location of the decimal 
point) rather than obsess over exact values.


From that perspective, 2mA on the DC cord of the K3 is not a seriously 
high level of RF leakage from a box that is generating 100W of RF. It is 
also notable that the output cable leading to the dummy load has only a 
few mA of common-mode current (contrast that with 1.4A of 
differential-mode RF current flowing *inside* the shield).  My IC-746 
gave very similar results to the K3.


Therefore it seems unlikely that K3s in general would have enough RF 
leakage on the power cord to cause the problems you're seeing, Jim. That 
doesn't rule out the possibility of a fault on your particular rig... 
but maybe you should be looking for a broken shield connection or 
something else that has been disturbed by puling out the previous rig 
and installing the K3.


Most likely of all is a broken shield connection on a PL-259, which can 
let out high levels of RF current, which then crawls over the whole 
station.



3. I can see some modulation-induced fluctuationss on the 12V line with
an oscilloscope that increase with the K3?s power setting. I haven?t
looked at these fluctuations closely enough yet to know whether it?s RF
noise or just audio?frequency  fluctuations caused by the K3?s
modulating current draw from the power supply.

 

To summarize, my conclusions so far are that (1) the 12V power cord is
a source of RF leakage from the K3,  even though the K3 has a filter at
its 12V power connector to minimize this leakage; and (2) The
audio/DSP circuitry in the K3 is very sensitive to RF ? much more so
than other transceivers in my station.  (I?ve not had this problem with
other rigs.)

 

Because of this RF sensitivity, one evidently has to be very careful 
when hooking accessories to the K3. The front panel microphone jack
is (to me) wired in a curious way, with the Mic ground and PTT ground
(shield) connections floating above the K3?s chassis with a 100uH rf
choke. Similarly, both the ?hot? and ?shield? side of the rear panel mic
input jack has series 100uH rf chokes, which isolate the input from
chassis ground.

 

The problem with this arrangement is that most accessories that would
connect to the rear panel audio input jacks have single-ended outputs,
with a shielded cable that is directly tied to chassis ground at the
accessory end of the cable. Thus, unless one is very careful, it is easy
to have a situtation where the signal grounds in the audio circuitry of
the K3 can fluctuate with respect to the K3?s chassis ground, and this
may be the source of the RF feedback sensitivity.


Unfortunately, I can?t figure out the detailed mechanism for the 
feedback closely enough to figure out a solution. Foir example, I don?t 
know whet

RE: [Elecraft] Help!

[Dick Dievendorff]

Thanks for the follow-up response, Tom.  Problems like this can give one a
sinking feeling...  

Very glad you're QRV now.

I'm getting ready for Sweepstakes now, our club's big domestic contest of
the year.   I'm in Nevada.

73 de Dick, K6KR


-Original Message-
From: Tom Wylie [mailto:[EMAIL PROTECTED] 
Sent: Saturday, November 01, 2008 10:39 AM
To: Dick Dievendorff
Subject: Re: [Elecraft] Help!

Absolutely correct DIck - appears to have been a faulty serial cable - 
my first ever.
Cold sweat now over   hihi
K3 singing merrily.

Thanks for the guidance

73 de Tom
GM4FDM

Dick Dievendorff wrote:
> Do you have a direct connection between your computer and the K3?  Not
> through something like a microHAM controller, right?
>
> I test this all the time.  It's usually a cabling problem between the PC
and
> the K3.  
>
> Please use the K3 Utility's Port Tab "test communications" button or
restart
> the K3 Utility (both cause the K3 Utility to try communications at all
baud
> rates).  The K3 in its "boot loader" state (which is indicated by the red
Tx
> LED and "MCU LD" in the display (which may not be lit) will communicate at
> only 38,400 bps.  The K3 Utility's Test Communications button should
detect
> that the K3 is at this baud rate and show a "warning" (exclamation point)
> dialog box with that baud rate in it.  
>
> It might help to beg or borrow a different RS-232 cable.
>
> These problems are frightening, but are most often due to a
straightforward
> cabling problem.
>
> Dick, K6KR
>
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Tom Wylie
> Sent: Saturday, November 01, 2008 7:09 AM
> To: elecraft@mailman.qth.net
> Subject: [Elecraft] Help!
>
> This afternoon I tried to upgrade the firmware and got a problen.
>
> Now the K3  TX LED is blinking and the LCD display shows MCU  LD
>
> Referring to the handbook It says I should reload the firmware...
>
> My computers tells me the K3 is not responding and wont upload the new 
> firmware.
>
> Forcing a firmware Download:tried unplugging hte power from the K3 
> as suggested for 10 seconds,  held the POWER switch for 10 seconds  
> TX LED is now flashing as above and I still have MCU  LD on the LCD 
> Display and the computer STILL tells me the K3 is not 
> res[ponding...Where do I go from here?
>
>
> Tom
> GM4FDM
>
>   

-- 
So I met the bloke who invented crosswords today. I can't remember his
name, it's P something T something R.



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[Elecraft] Reminder - UK Elecraft net Sundays 0900 local, 3630 KHz

[Dave G4AON]

The frequency as always is plus or minus the QRM. There appears to be CW 
and SSB contests running on 80m, maybe another morning for keeping the 
shack warm with linears!


73 Dave, G4AON
K3/100, Acom 1000, dipole
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[Elecraft] K3 default data mode

[Dave Hachadorian]

Every time I switch to data mode, the K3 comes up in AFSK A, 
which I never use. Is there a way to have it default to FSK 
D?


Dave Hachadorian, K6LL
Yuma, AZ
























. 


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RE: [Elecraft] K3 RF Feedback Problem

[4CX250B]

Hi Jamie,
My station controller is a homebrewed unit that switches up to 25 different 
control and signal lines (mic, key, speakers, data, Line In/Out, amp relay, 
packet, etc.) for three radios  and three amplifiers, in any combination. The 
controller also operates a separate RF relay unit that transfers all the 
RF-carrying coax lines (rated 3 kW). It was a year-long project to design and 
build. (Actually, I have three of them, and they can be networked together, 
allowing control of 9 rigs and 9 amplifiers.) An LCD display shows what 
radios/amplifiers are currently selected. At some point, I'll write an article 
on it for a ham magazine. The unit (controller and RF relay box) all use 
printed circuit boards, so other than the microphone jacks (two mics can be 
selected), there is no point-to-point wiring. I've been testing it out with 
various radios, ironing out a few bugs, but have found no real problems other 
than the aforementioned problem with feedback in the K3.
73,
Jim W8ZR

From: James C. Hall, MD [EMAIL PROTECTED]
Sent: Saturday, November 01, 2008 11:13 AM
To: 4CX250B; elecraft@mailman.qth.net
Cc: 'W. Douglas McDowell'
Subject: RE: [Elecraft] K3 RF Feedback Problem

Hi Jim:

I’m wondering what external station controller you are using. I’m using a NCS 
Multi-Switcher and I ran into very similar issues. I certainly felt (as did 
Doug at NCS) that it was a ground loop problem. I used transformer isolated 
mike cables and found that it was NOT a ground problem. I can give you my long 
details, but the bottom line is that the mike gain in the Multi-Switcher 
(internal) needed to be driven a bit higher than normal, and the mike gain on 
the K3 need to be quite low (5 or 6) to avoid the ‘growl’ effect. I’m 
forwarding this to Doug at NCS as he is quite interested in what’s going on 
that might be causing this.

73, Jamie
WB4YDL


From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dr. James C. 
Garland
Sent: Saturday, November 01, 2008 8:57 AM
To: elecraft@mailman.qth.net
Subject: [Elecraft] K3 RF Feedback Problem

Gang,

I’m pulling my hair out over an RF feedback problem with my K3/100, and wonder 
if anybody has any ideas? I use an external station controller that switches 
key, microphone, CAT, line in/out, etc. between different rigs.  The microphone 
audio connects to the K3’s rear panel microphone jack and when the K3’s power 
exceeds about 15W (in SSB), the audio becomes greatly istorted. It does this 
when all the other cables to the K3 (except the microphone and power cord) are 
unplugged. It also does it when the audio is fed to the K3 via the rear Line In 
jack. Everything in my station is well-grounded. Here are some things I’ve 
noticed:

1.  The feedback still occurs when a military-type completely shielded 100W 
dummy load is screwed directly to the K3’s antenna port. This suggests the RF 
from the K3 is getting into the audio line from some other source than 
radiation from the coax cables in the station, most likely the 12V power cord. 
To support this conjecture, I also notice that the feedback threshold (15W) is 
not changed when the K3 drives a linear amplifier.

2.  I normally use a 30A Kepco 12V power supply to run the K3 and my other 
station accessories. The RF feedback problem is improved but not entirely 
eliminated if I use a separate 12V supply for the K3. A common mode choke on 
the 12V line doesn’t appear to make any difference.

3. I can see some modulation-induced fluctuationss on the 12V line with an 
oscilloscope that increase with the K3’s power setting. I haven’t looked at 
these fluctuations closely enough yet to know whether it’s RF noise or just 
audio—frequency  fluctuations caused by the K3’s modulating current draw from 
the power supply.

To summarize, my conclusions so far are that (1) the 12V power cord is a source 
of RF leakage from the K3,  even though the K3 has a filter at its 12V power 
connector to minimize this leakage; and (2) The audio/DSP circuitry in the K3 
is very sensitive to RF – much more so than other transceivers in my station.  
(I’ve not had this problem with other rigs.)

Because of this RF sensitivity, one evidently has to be very careful  when 
hooking accessories to the K3. The front panel microphone jack is (to me) wired 
in a curious way, with the Mic ground and PTT ground (shield) connections 
floating above the K3’s chassis with a 100uH rf choke. Similarly, both the 
“hot” and “shield” side of the rear panel mic input jack has series 100uH rf 
chokes, which isolate the input from chassis ground.

The problem with this arrangement is that most accessories that would connect 
to the rear panel audio input jacks have single-ended outputs, with a shielded 
cable that is directly tied to chassis ground at the accessory end of the 
cable. Thus, unless one is very careful, it is easy to have a situtation where 
the signal grounds in the audio circu

Re: [Elecraft] Bigger K3 S-meter

[K7TV]

Guy,

I too would like that capability, *but* it would not make sense to use the
K3 this way unless it has the long term gain stability (including vs.
temperature changes) to support it. In response to my raising that issue,
Geoff (GM4ESD) emailed me off list to suggest that the J-FET used used in
the K3 signal chain before the DSP (used in the hardware AGC loop unless I
am mistaken) may be a source of gain variation with temperature. On the
other hand, I would think that the K3 receive gain would be more stable
against temperature variations than an analog receiver that might have many
more stages that are susceptible.
I don't know if the K3 hardware is stable enough to be used as a calibrated
uV meter. If it is, then no doubt we will eventually see software and
firmware to make use of it. If not, then I would not fault Wayne, since a
designer cannot please everybody, and he must design for the goals that make
economic sense to him. 

It has been pointed out that some software defined receivers (presumably
without analog stages) can function well as calibrated signal strenght
meters for received signals. Personally I would want something like that
anyway, for the panoramic reception capability, so that makes me less
impatient for the K3 to be proven as or disproven as a precision RF
voltmeter. (I would still like to have a high-resolution S-meter, though,
inaccurate or not. Thanks Don Rasmussen for sharing your approach.). I have
a SoftRock Lite in the pipeline for a first panadapter attempt. The price of
that is so low that it isn't very important whether it is good enough or
not. If it is not, I will just move on to something better. It would be
interesting to know what you give up if you get, say, an SDR-IQ vs. a
Perseus. Of course the LP-Pan is also an alternative.

73,
Erik K7TV





I'd like to be able to calibrate it to 1 uV and 50 uV and know that the
noise on the band is -10 or +3 dBuV and that the signal from a friend has
gone down to +18 from +26 last week and previous.  That requires a
calibration, and while one could just use what the rig does naturally as a
reference, the K3 has changing SDR code, and maintaining a calibration on a
reference source sure does simplify things.

To another objection earlier in the thread, inexpensive test equipment
doesn't have selectability to narrow down on a single CW signal. So I'm
looking at the firmware only abilities (not hardware) of a K3 to do
something that has always been a bear.  Other SDR's have it, so I figure
Wayne will get to it in time, and I will have a piece of on-the-air test
gear that I've never had, and prior to now couldn't get without taking out a
mortgage.

73, Guy.

-- 
View this message in context: 
http://n2.nabble.com/Bigger-K3-S-meter-tp1399030p1442642.html
Sent from the Elecraft mailing list archive at Nabble.com.

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RE: [Elecraft] K3 Firmware 2.58

[Bill Johnson]

Wayne, Joe and Julian,

Thank you!  I will change to the 0051.  If I want lower will send 0050.  One
watt increments work for me.  I usually use 2 watts or 75, very little in
between.  I will use my K2 for variations in between if I so choose.  


73,

Bill
K9YEQ
K2 #35; KX1 #35; K3 #1744; mini mods


-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Joe Subich, W4TV
Sent: Friday, October 31, 2008 6:53 PM
To: 'Julian, G4ILO'; elecraft@mailman.qth.net
Subject: RE: [Elecraft] K3 Firmware 2.58


Julian, 

Assuming you are using the K22; extended mode, use 
PC0051; to set 5 Watts (5 Watts, high range).  The 
PC0500; sets to 5.0 Watts in the low range (turns 
off the PA).  

The only downside to using the PC0051; syntax is that 
you can't set the power to other than integral values 
of power (2.0, 3.0, 4.0, etc. Watts).  

73, 

   ... Joe, W4TV 
   



> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On Behalf Of Julian, G4ILO
> Sent: Friday, October 31, 2008 5:44 PM
> To: elecraft@mailman.qth.net
> Subject: RE: [Elecraft] K3 Firmware 2.58
> 
> 
> 
> 
> 
> Bill Johnson-9 wrote:
> > 
> > Julian,
> > 
> > Here's what's in the command:  PC0500;PC;DS;
> > 
> > I tried it again and I get the same thing.  The power cannot be 
> > adjusted with the front panel dial past 12 watts.
> > 
> > 
> > Bill
> > 
> You are right. Perhaps someone can advise how to reduce power 
> to below 12W by software command without disabling the 
> ability to increase it above that level again using the front 
> panel control.
> 
> -
> Julian, G4ILO. K2 #392  K3 #222.
> http://www.g4ilo.com/ G4ILO's Shack   
> http://www.ham-directory.com/ Ham
> Directoryhttp://www.g4ilo.com/kcomm.html KComm for 
> Elecraft K2 and K3 
> -- 
> View this message in context: 
> http://n2.nabble.com/K3-Firmware-2.58-tp1437773p1438626.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> 
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RE: [Elecraft] K3 RF Feedback Problem

[4CX250B]

Very interesting, Paul. I was aware of the isolation chokes, but hadn't known 
anybody to try jumpering them. I'd be interesting in hearing one of the K3 
designers explain what they had in mind by wiring the audio inputs this way. 
Perhaps it has something to do with using balanced line audio sources. 
Minimizing ground loops can be a headache when one has multiple audio devices, 
powered by different power supplies.

73,
Jim W8ZR

From: Paul Christensen [EMAIL PROTECTED]
Sent: Saturday, November 01, 2008 10:03 AM
To: 4CX250B; elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 RF Feedback Problem

Jim,

This may, or may not be the root cause of your RFI problem, but it is important 
to note that the K3 elevates the ground potential on both the front and rear 
panel MIC connectors.  This is not a trivial issue.  L7 is a 100 uH choke that 
isolates the ring of the rear panel TRS connector (J20) from chassis ground.

In the same manner, L4 (another 100 uH) RFC) isolates ground pins 7 & 8 on the 
front panel MIC jack from chassis ground.  The net effect of these chokes 
results in an "ungrounding" of the MIC inputs.. The addition of the chokes is 
something completely opposite of what is required in this part of the circuit.

When conducting other K3 audio mods, I went in and removed both L4 and L7, and 
jumpered the solder pads with 24 AWG buss wire.

In my case, RFI problems 100% solved.

Paul, W9AC

- Original Message -
From: Dr. James C. Garland
To: elecraft@mailman.qth.net
Sent: Saturday, November 01, 2008 9:57 AM
Subject: [Elecraft] K3 RF Feedback Problem

Gang,

I’m pulling my hair out over an RF feedback problem with my K3/100, and wonder 
if anybody has any ideas? I use an external station controller that switches 
key, microphone, CAT, line in/out, etc. between different rigs.  The microphone 
audio connects to the K3’s rear panel microphone jack and when the K3’s power 
exceeds about 15W (in SSB), the audio becomes greatly istorted. It does this 
when all the other cables to the K3 (except the microphone and power cord) are 
unplugged. It also does it when the audio is fed to the K3 via the rear Line In 
jack. Everything in my station is well-grounded. Here are some things I’ve 
noticed:

1.  The feedback still occurs when a military-type completely shielded 100W 
dummy load is screwed directly to the K3’s antenna port. This suggests the RF 
from the K3 is getting into the audio line from some other source than 
radiation from the coax cables in the station, most likely the 12V power cord. 
To support this conjecture, I also notice that the feedback threshold (15W) is 
not changed when the K3 drives a linear amplifier.

2.  I normally use a 30A Kepco 12V power supply to run the K3 and my other 
station accessories. The RF feedback problem is improved but not entirely 
eliminated if I use a separate 12V supply for the K3. A common mode choke on 
the 12V line doesn’t appear to make any difference.

3. I can see some modulation-induced fluctuationss on the 12V line with an 
oscilloscope that increase with the K3’s power setting. I haven’t looked at 
these fluctuations closely enough yet to know whether it’s RF noise or just 
audio—frequency  fluctuations caused by the K3’s modulating current draw from 
the power supply.

To summarize, my conclusions so far are that (1) the 12V power cord is a source 
of RF leakage from the K3,  even though the K3 has a filter at its 12V power 
connector to minimize this leakage; and (2) The audio/DSP circuitry in the K3 
is very sensitive to RF – much more so than other transceivers in my station.  
(I’ve not had this problem with other rigs.)

Because of this RF sensitivity, one evidently has to be very careful  when 
hooking accessories to the K3. The front panel microphone jack is (to me) wired 
in a curious way, with the Mic ground and PTT ground (shield) connections 
floating above the K3’s chassis with a 100uH rf choke. Similarly, both the 
“hot” and “shield” side of the rear panel mic input jack has series 100uH rf 
chokes, which isolate the input from chassis ground.

The problem with this arrangement is that most accessories that would connect 
to the rear panel audio input jacks have single-ended outputs, with a shielded 
cable that is directly tied to chassis ground at the accessory end of the 
cable. Thus, unless one is very careful, it is easy to have a situtation where 
the signal grounds in the audio circuitry of the K3 can fluctuate with respect 
to the K3’s chassis ground, and this may be the source of the RF feedback 
sensitivity.

Unfortunately, I can’t figure out the detailed mechanism for the feedback 
closely enough to figure out a solution. Foir example, I don’t know whether 
it’s better to leave the minus side of my 12V power supply floating, or to tie 
it to the chassis gound..  And even if I left it floating, it would be tied to 
the ch

RE: [Elecraft] K3 RF Feedback Problem

[James C. Hall, MD]

Hi Jim:

 

I'm wondering what external station controller you are using. I'm using a
NCS Multi-Switcher and I ran into very similar issues. I certainly felt (as
did Doug at NCS) that it was a ground loop problem. I used transformer
isolated mike cables and found that it was NOT a ground problem. I can give
you my long details, but the bottom line is that the mike gain in the
Multi-Switcher (internal) needed to be driven a bit higher than normal, and
the mike gain on the K3 need to be quite low (5 or 6) to avoid the 'growl'
effect. I'm forwarding this to Doug at NCS as he is quite interested in
what's going on that might be causing this.

 

73, Jamie

WB4YDL

 

  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Dr. James C. Garland
Sent: Saturday, November 01, 2008 8:57 AM
To: elecraft@mailman.qth.net
Subject: [Elecraft] K3 RF Feedback Problem

 

Gang,

 

I'm pulling my hair out over an RF feedback problem with my K3/100, and
wonder if anybody has any ideas? I use an external station controller that
switches key, microphone, CAT, line in/out, etc. between different rigs.
The microphone audio connects to the K3's rear panel microphone jack and
when the K3's power exceeds about 15W (in SSB), the audio becomes greatly
istorted. It does this when all the other cables to the K3 (except the
microphone and power cord) are unplugged. It also does it when the audio is
fed to the K3 via the rear Line In jack. Everything in my station is
well-grounded. Here are some things I've noticed:

 

1.  The feedback still occurs when a military-type completely shielded 100W
dummy load is screwed directly to the K3's antenna port. This suggests the
RF from the K3 is getting into the audio line from some other source than
radiation from the coax cables in the station, most likely the 12V power
cord. To support this conjecture, I also notice that the feedback threshold
(15W) is not changed when the K3 drives a linear amplifier. 

 

2.  I normally use a 30A Kepco 12V power supply to run the K3 and my other
station accessories. The RF feedback problem is improved but not entirely
eliminated if I use a separate 12V supply for the K3. A common mode choke on
the 12V line doesn't appear to make any difference. 

 

3. I can see some modulation-induced fluctuationss on the 12V line with an
oscilloscope that increase with the K3's power setting. I haven't looked at
these fluctuations closely enough yet to know whether it's RF noise or just
audio-frequency  fluctuations caused by the K3's modulating current draw
from the power supply.

 

To summarize, my conclusions so far are that (1) the 12V power cord is a
source of RF leakage from the K3,  even though the K3 has a filter at its
12V power connector to minimize this leakage; and (2) The audio/DSP
circuitry in the K3 is very sensitive to RF - much more so than other
transceivers in my station.  (I've not had this problem with other rigs.) 

 

Because of this RF sensitivity, one evidently has to be very careful  when
hooking accessories to the K3. The front panel microphone jack is (to me)
wired in a curious way, with the Mic ground and PTT ground (shield)
connections floating above the K3's chassis with a 100uH rf choke.
Similarly, both the "hot" and "shield" side of the rear panel mic input jack
has series 100uH rf chokes, which isolate the input from chassis ground. 

 

The problem with this arrangement is that most accessories that would
connect to the rear panel audio input jacks have single-ended outputs, with
a shielded cable that is directly tied to chassis ground at the accessory
end of the cable. Thus, unless one is very careful, it is easy to have a
situtation where the signal grounds in the audio circuitry of the K3 can
fluctuate with respect to the K3's chassis ground, and this may be the
source of the RF feedback sensitivity.

 

Unfortunately, I can't figure out the detailed mechanism for the feedback
closely enough to figure out a solution. Foir example, I don't know whether
it's better to leave the minus side of my 12V power supply floating, or to
tie it to the chassis gound..  And even if I left it floating, it would be
tied to the chassis anyway by the other accessories hooked to it, and this
might cause more problems than grounding it at the power supply terminal.
Somehow, it seems like a wiring change in the ground configuration of the
K3's audio circutis to improve RF isolation may be needed to lick the
problem completely.

 

73,

 

Jim Garland W8ZR

 

 

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Re: [Elecraft] K3 RF Feedback Problem

[Paul Christensen]

Jim,

This may, or may not be the root cause of your RFI problem, but it is important 
to note that the K3 elevates the ground potential on both the front and rear 
panel MIC connectors.  This is not a trivial issue.  L7 is a 100 uH choke that 
isolates the ring of the rear panel TRS connector (J20) from chassis ground.  

In the same manner, L4 (another 100 uH) RFC) isolates ground pins 7 & 8 on the 
front panel MIC jack from chassis ground.  The net effect of these chokes 
results in an "ungrounding" of the MIC inputs.. The addition of the chokes is 
something completely opposite of what is required in this part of the circuit.  

When conducting other K3 audio mods, I went in and removed both L4 and L7, and 
jumpered the solder pads with 24 AWG buss wire.  

In my case, RFI problems 100% solved.

Paul, W9AC
  
  - Original Message - 
  From: Dr. James C. Garland 
  To: elecraft@mailman.qth.net 
  Sent: Saturday, November 01, 2008 9:57 AM
  Subject: [Elecraft] K3 RF Feedback Problem


  Gang,

   

  I'm pulling my hair out over an RF feedback problem with my K3/100, and 
wonder if anybody has any ideas? I use an external station controller that 
switches key, microphone, CAT, line in/out, etc. between different rigs.  The 
microphone audio connects to the K3's rear panel microphone jack and when the 
K3's power exceeds about 15W (in SSB), the audio becomes greatly istorted. It 
does this when all the other cables to the K3 (except the microphone and power 
cord) are unplugged. It also does it when the audio is fed to the K3 via the 
rear Line In jack. Everything in my station is well-grounded. Here are some 
things I've noticed:

   

  1.  The feedback still occurs when a military-type completely shielded 100W 
dummy load is screwed directly to the K3's antenna port. This suggests the RF 
from the K3 is getting into the audio line from some other source than 
radiation from the coax cables in the station, most likely the 12V power cord. 
To support this conjecture, I also notice that the feedback threshold (15W) is 
not changed when the K3 drives a linear amplifier. 

   

  2.  I normally use a 30A Kepco 12V power supply to run the K3 and my other 
station accessories. The RF feedback problem is improved but not entirely 
eliminated if I use a separate 12V supply for the K3. A common mode choke on 
the 12V line doesn't appear to make any difference. 

   

  3. I can see some modulation-induced fluctuationss on the 12V line with an 
oscilloscope that increase with the K3's power setting. I haven't looked at 
these fluctuations closely enough yet to know whether it's RF noise or just 
audio-frequency  fluctuations caused by the K3's modulating current draw from 
the power supply.

   

  To summarize, my conclusions so far are that (1) the 12V power cord is a 
source of RF leakage from the K3,  even though the K3 has a filter at its 12V 
power connector to minimize this leakage; and (2) The audio/DSP circuitry in 
the K3 is very sensitive to RF - much more so than other transceivers in my 
station.  (I've not had this problem with other rigs.) 

   

  Because of this RF sensitivity, one evidently has to be very careful  when 
hooking accessories to the K3. The front panel microphone jack is (to me) wired 
in a curious way, with the Mic ground and PTT ground (shield) connections 
floating above the K3's chassis with a 100uH rf choke. Similarly, both the 
"hot" and "shield" side of the rear panel mic input jack has series 100uH rf 
chokes, which isolate the input from chassis ground. 

   

  The problem with this arrangement is that most accessories that would connect 
to the rear panel audio input jacks have single-ended outputs, with a shielded 
cable that is directly tied to chassis ground at the accessory end of the 
cable. Thus, unless one is very careful, it is easy to have a situtation where 
the signal grounds in the audio circuitry of the K3 can fluctuate with respect 
to the K3's chassis ground, and this may be the source of the RF feedback 
sensitivity.

   

  Unfortunately, I can't figure out the detailed mechanism for the feedback 
closely enough to figure out a solution. Foir example, I don't know whether 
it's better to leave the minus side of my 12V power supply floating, or to tie 
it to the chassis gound..  And even if I left it floating, it would be tied to 
the chassis anyway by the other accessories hooked to it, and this might cause 
more problems than grounding it at the power supply terminal. Somehow, it seems 
like a wiring change in the ground configuration of the K3's audio circutis to 
improve RF isolation may be needed to lick the problem completely.

   

  73,

   

  Jim Garland W8ZR

   

   



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Re: [Elecraft] Bigger K3 S-meter

[Guy, K2AV]

I'd like to be able to calibrate it to 1 uV and 50 uV and know that the noise
on the band is -10 or +3 dBuV and that the signal from a friend has gone
down to +18 from +26 last week and previous.  That requires a calibration,
and while one could just use what the rig does naturally as a reference, the
K3 has changing SDR code, and maintaining a calibration on a reference
source sure does simplify things.

To another objection earlier in the thread, inexpensive test equipment
doesn't have selectability to narrow down on a single CW signal. So I'm
looking at the firmware only abilities (not hardware) of a K3 to do
something that has always been a bear.  Other SDR's have it, so I figure
Wayne will get to it in time, and I will have a piece of on-the-air test
gear that I've never had, and prior to now couldn't get without taking out a
mortgage.

73, Guy.


David Woolley (E.L) wrote:
> 
> Guy, K2AV wrote:
>> beam kind of thing.  Although that can be done relatively with the audio
>> voltage level, it wouldn't allow me to tell a local that his ground wave
>> signal has gone down 3 db and is staying there, or be able to create data
>> for studies over time.  
> 
> You only require that both measurements be relative to the same 
> reference, not that the absolute value of that reference be known.  3dB 
> always represents the same ratio.
> 
> 
> 
> -- 
> David Woolley
> "The Elecraft list is a forum for the discussion of topics related to 
> Elecraft products and more general topics related ham radio"
> List Guidelines 
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> 
> 

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[Elecraft] RE: K3 Bigger S-Meter

[Dave Agsten]

Right on Joe " If you want a test instrument, purchase a test instrument 
and don't load up the cost of the K3 for all of the other 
users. "

It seems like a few folks are never satisfied. They want more and more and 
more... It seems like there is no end to it.

I don't think too many folks really worry themselves to death over the S-Meter 
reading. I'm more concerned with being able to just copy a cw signal, not 
wondering if it's S6 or S7. It seems rather silly.

73,
Dave N8AG




  
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RE: [Elecraft] Help!

[Dick Dievendorff]

Do you have a direct connection between your computer and the K3?  Not
through something like a microHAM controller, right?

I test this all the time.  It's usually a cabling problem between the PC and
the K3.  

Please use the K3 Utility's Port Tab "test communications" button or restart
the K3 Utility (both cause the K3 Utility to try communications at all baud
rates).  The K3 in its "boot loader" state (which is indicated by the red Tx
LED and "MCU LD" in the display (which may not be lit) will communicate at
only 38,400 bps.  The K3 Utility's Test Communications button should detect
that the K3 is at this baud rate and show a "warning" (exclamation point)
dialog box with that baud rate in it.  

It might help to beg or borrow a different RS-232 cable.

These problems are frightening, but are most often due to a straightforward
cabling problem.

Dick, K6KR

-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Tom Wylie
Sent: Saturday, November 01, 2008 7:09 AM
To: elecraft@mailman.qth.net
Subject: [Elecraft] Help!

This afternoon I tried to upgrade the firmware and got a problen.

Now the K3  TX LED is blinking and the LCD display shows MCU  LD

Referring to the handbook It says I should reload the firmware...

My computers tells me the K3 is not responding and wont upload the new 
firmware.

Forcing a firmware Download:tried unplugging hte power from the K3 
as suggested for 10 seconds,  held the POWER switch for 10 seconds  
TX LED is now flashing as above and I still have MCU  LD on the LCD 
Display and the computer STILL tells me the K3 is not 
res[ponding...Where do I go from here?


Tom
GM4FDM

-- 
So I met the bloke who invented crosswords today. I can't remember his
name, it's P something T something R.



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[Elecraft] RE: K3 RF Feedback Problem

[Dr. James C. Garland]

Thanks to all for your replies and interest. To answer some raised
questions: 

(1) The K3 works well (no feedback) with an MH-2 microphone connected to the
front panel jack. The problem comes about when any other audio source (e.g.,
another microphone, or W2IHY Eq Plus) is connected to the rear panel mic
jack. Unfortunately, I can't easily connect another microphone directly to
the rear jack, without routing it first through my station controller.
However, I _can_ route the EQ Plus directly into the rear panel jack,
bypassing the controller, and see no change in the feedback problem. I've
not had the feedback problem with three other rigs I've tested.

(2) My test with the dummy load connected directly to the antenna input on
the K3 was intended to establish that RF was not getting into the audio by
radiation from coax cables in the shack. My best guess is that RF is
"leaking" out of the K3's power cable into my 12V distribution panel, and
from there into the audio line of connected devices.

(3) I'm not 100% sure that the problem is actually caused by RF. It might be
caused by audio modulation of the 12V on my power distribution panel
resulting from fluctuations of the DC current when the K3 is voice
modulated. One way to check that possibility, which I plan to do today, is
to see if the problem persists when the K3 is operating in AM and the power
supply current is roughly constant. I also plan to look at the audio and 12V
lines with a scope. I'll let you all know what I find. However, since I've
experienced no other problems using the identical hookup with other rigs,
e.g., a Yaesu FT-2000D, I can't help but think the K3 is abnormally
sensitive to this kind of problem.

73,

Jim W8ZR

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Re: [Elecraft] Bigger K3 S-meter

[David Woolley (E.L)]

Guy, K2AV wrote:

beam kind of thing.  Although that can be done relatively with the audio
voltage level, it wouldn't allow me to tell a local that his ground wave
signal has gone down 3 db and is staying there, or be able to create data
for studies over time.  


You only require that both measurements be relative to the same 
reference, not that the absolute value of that reference be known.  3dB 
always represents the same ratio.




--
David Woolley
"The Elecraft list is a forum for the discussion of topics related to 
Elecraft products and more general topics related ham radio"

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Re: [Elecraft] Sub Receiver Question

[Iain MacDonnell - K6IAM]

-.-. --.-N3TU -.-. --.- wrote:

How do I get the sub receiver to receive? I can hear my main receiver on the
left speaker and static on the right receiver.  It sounds like I don't have
an antenna on the sub. I checked the sub receiver's frequency with the main
receiver and there is activity on the band. 


Have you selected the right antenna input for the sub-RX? Hold BSET,
then tap ANT. See page 37 of the owner's manual.

~Iain
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Re: [Elecraft] Is There A Desk Mic with a MH2 element?

[Dave G4AON]

We have all sorts of microphones in use on the UK Elecraft (SSB) net and 
they mostly sound fine. One or two sound really great but that might be 
more related to the user's voice than the microphone. The Heil Goldline 
usually sounds good, that is using the "Pro" broadcast element as 
opposed to the HC-4 or 5 (they have a wide/narrow toggle switch and 
include the "Pro" and either HC-4 or 5 element). However all manner of 
microphones can be made to sound good with the equaliser!


73 Dave, G4AON
K3/100 #80, using a Sony ECM-MS907 mic (which just happened to be to hand)
-
I have tried all kinds of mics on my K3 but the hand mic that came with the
radio sounds nice and rich. Somehow the transmit EQ gives me greater range
with this mic that has the MH2 element compared to the other mics. I don't
tell anyone at first that I am running a K3 and they are complimenting me on
the audio. Is there a desk mic with the MH2 element?
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Re: [Elecraft] K3 RF Feedback Problem

[Dave G4AON]

You "can't" have RF feedback if you are using a dummy load, unless one 
of the connectors/leads inside the K3 isn't properly connected - 
allowing high levels or RF inside the cabinet.


As per Stewart's comment, have you tried a directly connected mic and 
also are you sure that power supply isn't causing a problem?


73 Dave, G4AON
K3/100 #80
-
Have you tried just running the mic into your K3 without the
external station controller ?
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Re: [Elecraft] K3 RF Feedback Problem

[Stewart Baker]

Have you tried just running the mic into your K3 without the
external station controller ?
What is that controller ?

73
Stewart G3RXQ
On Sat, 1 Nov 2008 07:57:10 -0600, Dr. James C. Garland wrote:
> Gang,
>
>
> I’m pulling my hair out over an RF feedback problem with my
K3/100, and wonder if
> anybody has any ideas? I use an external station controller that
switches key,
> microphone, CAT, line in/out, etc. between different rigs.  The
microphone audio
> connects to the K3’s rear panel microphone jack and when the
K3’s power exceeds about
> 15W (in SSB), the audio becomes greatly istorted. It does this
when all the other
> cables to the K3 (except the microphone and power cord) are
unplugged. It also does it
> when the audio is fed to the K3 via the rear Line In jack.
Everything in my station is
> well-grounded. Here are some things I’ve noticed:
>
>
> 1.  The feedback still occurs when a military-type completely
shielded 100W dummy load
> is screwed directly to the K3’s antenna port. This suggests the
RF from the K3 is
> getting into the audio line from some other source than
radiation from the coax cables
> in the station, most likely the 12V power cord. To support this
conjecture, I also
> notice that the feedback threshold (15W) is not changed when the
K3 drives a linear
> amplifier.
>
>
> 2.  I normally use a 30A Kepco 12V power supply to run the K3
and my other station
> accessories. The RF feedback problem is improved but not
entirely eliminated if I use a
> separate 12V supply for the K3. A common mode choke on the 12V
line doesn’t appear to
> make any difference.
>
>
> 3. I can see some modulation-induced fluctuationss on the 12V
line with an oscilloscope
> that increase with the K3’s power setting. I haven’t looked at
these fluctuations
> closely enough yet to know whether it’s RF noise or just
audio—frequency  fluctuations
> caused by the K3’s modulating current draw from the power
supply.
>
>
> To summarize, my conclusions so far are that (1) the 12V power
cord is a source of RF
> leakage from the K3,  even though the K3 has a filter at its 12V
power connector to
> minimize this leakage; and (2) The audio/DSP circuitry in the K3
is very sensitive to
> RF – much more so than other transceivers in my station.  (I’ve
not had this problem
> with other rigs.)
>
>
> Because of this RF sensitivity, one evidently has to be very
careful  when hooking
> accessories to the K3. The front panel microphone jack is (to
me) wired in a curious
> way, with the Mic ground and PTT ground (shield) connections
floating above the K3’s
> chassis with a 100uH rf choke. Similarly, both the “hot” and
“shield” side of the rear
> panel mic input jack has series 100uH rf chokes, which isolate
the input from chassis
> ground.
>
>
> The problem with this arrangement is that most accessories that
would connect to the
> rear panel audio input jacks have single-ended outputs, with a
shielded cable that is
> directly tied to chassis ground at the accessory end of the
cable. Thus, unless one is
> very careful, it is easy to have a situtation where the signal
grounds in the audio
> circuitry of the K3 can fluctuate with respect to the K3’s
chassis ground, and this may
> be the source of the RF feedback sensitivity.
>
>
> Unfortunately, I can’t figure out the detailed mechanism for the
feedback closely
> enough to figure out a solution. Foir example, I don’t know
whether it’s better to
> leave the minus side of my 12V power supply floating, or to tie
it to the chassis
> gound..  And even if I left it floating, it would be tied to the
chassis anyway by the
> other accessories hooked to it, and this might cause more
problems than grounding it at
> the power supply terminal. Somehow, it seems like a wiring
change in the ground
> configuration of the K3’s audio circutis to improve RF isolation
may be needed to lick
> the problem completely.
>
>
> 73,
>
>
> Jim Garland W8ZR


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[Elecraft] Help!

[Tom Wylie]

This afternoon I tried to upgrade the firmware and got a problen.

Now the K3  TX LED is blinking and the LCD display shows MCU  LD

Referring to the handbook It says I should reload the firmware...

My computers tells me the K3 is not responding and wont upload the new 
firmware.


Forcing a firmware Download:tried unplugging hte power from the K3 
as suggested for 10 seconds,  held the POWER switch for 10 seconds  
TX LED is now flashing as above and I still have MCU  LD on the LCD 
Display and the computer STILL tells me the K3 is not 
res[ponding...Where do I go from here?



Tom
GM4FDM

--
So I met the bloke who invented crosswords today. I can't remember his
name, it's P something T something R.



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[Elecraft] K3 RF Feedback Problem

[Dr. James C. Garland]

Gang,

 

I'm pulling my hair out over an RF feedback problem with my K3/100, and
wonder if anybody has any ideas? I use an external station controller that
switches key, microphone, CAT, line in/out, etc. between different rigs.
The microphone audio connects to the K3's rear panel microphone jack and
when the K3's power exceeds about 15W (in SSB), the audio becomes greatly
istorted. It does this when all the other cables to the K3 (except the
microphone and power cord) are unplugged. It also does it when the audio is
fed to the K3 via the rear Line In jack. Everything in my station is
well-grounded. Here are some things I've noticed:

 

1.  The feedback still occurs when a military-type completely shielded 100W
dummy load is screwed directly to the K3's antenna port. This suggests the
RF from the K3 is getting into the audio line from some other source than
radiation from the coax cables in the station, most likely the 12V power
cord. To support this conjecture, I also notice that the feedback threshold
(15W) is not changed when the K3 drives a linear amplifier. 

 

2.  I normally use a 30A Kepco 12V power supply to run the K3 and my other
station accessories. The RF feedback problem is improved but not entirely
eliminated if I use a separate 12V supply for the K3. A common mode choke on
the 12V line doesn't appear to make any difference. 

 

3. I can see some modulation-induced fluctuationss on the 12V line with an
oscilloscope that increase with the K3's power setting. I haven't looked at
these fluctuations closely enough yet to know whether it's RF noise or just
audio-frequency  fluctuations caused by the K3's modulating current draw
from the power supply.

 

To summarize, my conclusions so far are that (1) the 12V power cord is a
source of RF leakage from the K3,  even though the K3 has a filter at its
12V power connector to minimize this leakage; and (2) The audio/DSP
circuitry in the K3 is very sensitive to RF - much more so than other
transceivers in my station.  (I've not had this problem with other rigs.) 

 

Because of this RF sensitivity, one evidently has to be very careful  when
hooking accessories to the K3. The front panel microphone jack is (to me)
wired in a curious way, with the Mic ground and PTT ground (shield)
connections floating above the K3's chassis with a 100uH rf choke.
Similarly, both the "hot" and "shield" side of the rear panel mic input jack
has series 100uH rf chokes, which isolate the input from chassis ground. 

 

The problem with this arrangement is that most accessories that would
connect to the rear panel audio input jacks have single-ended outputs, with
a shielded cable that is directly tied to chassis ground at the accessory
end of the cable. Thus, unless one is very careful, it is easy to have a
situtation where the signal grounds in the audio circuitry of the K3 can
fluctuate with respect to the K3's chassis ground, and this may be the
source of the RF feedback sensitivity.

 

Unfortunately, I can't figure out the detailed mechanism for the feedback
closely enough to figure out a solution. Foir example, I don't know whether
it's better to leave the minus side of my 12V power supply floating, or to
tie it to the chassis gound..  And even if I left it floating, it would be
tied to the chassis anyway by the other accessories hooked to it, and this
might cause more problems than grounding it at the power supply terminal.
Somehow, it seems like a wiring change in the ground configuration of the
K3's audio circutis to improve RF isolation may be needed to lick the
problem completely.

 

73,

 

Jim Garland W8ZR

 

 

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[Elecraft] Is There A Desk Mic with a MH2 element?

[-.-. --.-N3TU -.-. --.-]

I have tried all kinds of mics on my K3 but the hand mic that came with the
radio sounds nice and rich. Somehow the transmit EQ gives me greater range
with this mic that has the MH2 element compared to the other mics.  I don't
tell anyone at first that I am running a K3 and they are complimenting me on
the audio. Is there a desk mic with the MH2 element? 
-- 
View this message in context: 
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[Elecraft] Sub Receiver Question

[-.-. --.-N3TU -.-. --.-]

How do I get the sub receiver to receive? I can hear my main receiver on the
left speaker and static on the right receiver.  It sounds like I don't have
an antenna on the sub. I checked the sub receiver's frequency with the main
receiver and there is activity on the band. 
-- 
View this message in context: 
http://n2.nabble.com/Sub-Receiver-Question-tp1442011p1442011.html
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[Elecraft] K3:Problem with KPA3

[Michael van Hauten]

hi Folks,
my K3 works fine in the Low power mode. But when setting power to more than 
12W, i hear the relay switching but i get no output power, the dc power goes to 
20A  What happens? In the menue, KPA3 is set to nor. Do i have a short in the 
KPA3 or ist the problem a Menue setting?
Thanks for your help.
Michael, DC0ZO
K3 #1999___
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