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DIY Hard-drawn copper wire

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Edward A. Dauer

DIY Hard-drawn copper wire

In a recent post Jim, K9YC, suggested making hard-drawn copper wire for antennas by attaching a few hundred feet of bare copper wire to a tree or telephone pole at one end and to a bumper hitch at the other, then driving away very slowly until it snaps. That sounded like a very attractive idea - much in the ham tradition. I wondered, though, whether it could be done using a car without a bumper hitch. The minimum breaking strength of number 8 hard-drawn copper wire (though it might be closer to number 10 after being stretched) is between 644 and 826 pounds, according to a chart I found on the Internet. Rather than test it empirically with my 16-year-old SUV (no bumper hitch), I wondered what 700 or 800 pounds of shear force would do to an automobile frame, assuming attachment to a suitable bolt somewhere. Or would the tree fall over first?

Ted, KN1CBR
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NK7Z

Re: DIY Hard-drawn copper wire

But the real question is:

If the tree falls over, and no one hears it, did it really fall over,
and did the wire snap?

Sorry, I could not resist...
--
73's, and thanks,
Dave

For software/hardware reviews see:
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On Thu, 2016-02-11 at 14:34 +0000, Dauer, Edward wrote:

> In a recent post Jim, K9YC, suggested making hard-drawn copper wire
> for antennas by attaching a few hundred feet of bare copper wire to a
> tree or telephone pole at one end and to a bumper hitch at the other,
> then driving away very slowly until it snaps.  That sounded like a
> very attractive idea - much in the ham tradition.  I wondered,
> though, whether it could be done using a car without a bumper
> hitch.  The minimum breaking strength of number 8 hard-drawn copper
> wire (though it might be closer to number 10 after being stretched)
> is between 644 and 826 pounds, according to a chart I found on the
> Internet.  Rather than test it empirically with my 16-year-old SUV
> (no bumper hitch), I wondered what 700 or 800 pounds of shear force
> would do to an automobile frame, assuming attachment to a suitable
> bolt somewhere.  Or would the tree fall over first?
>
> Ted, KN1CBR
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Henry Pollock - K4TMC

Re: DIY Hard-drawn copper wire

Also...just in case...make sure the wire is longer than the height of the
tree...

73,
Henry - K4TMC

On Thu, Feb 11, 2016 at 9:57 AM, Dave Cole <[hidden email]> wrote:

> But the real question is:
>
> If the tree falls over, and no one hears it, did it really fall over,
> and did the wire snap?
>
> Sorry, I could not resist...
> --
> 73's, and thanks,
> Dave
>
> For software/hardware reviews see:
> http://www.nk7z.net
>
> For MixW support see:
> https://groups.yahoo.com/neo/groups/mixw/info
>
> For SSTV help see:
> http://groups.yahoo.com/neo/groups/MM-SSTV/info
>
>
>
> On Thu, 2016-02-11 at 14:34 +0000, Dauer, Edward wrote:
> > In a recent post Jim, K9YC, suggested making hard-drawn copper wire
> > for antennas by attaching a few hundred feet of bare copper wire to a
> > tree or telephone pole at one end and to a bumper hitch at the other,
> > then driving away very slowly until it snaps. That sounded like a
> > very attractive idea - much in the ham tradition. I wondered,
> > though, whether it could be done using a car without a bumper
> > hitch. The minimum breaking strength of number 8 hard-drawn copper
> > wire (though it might be closer to number 10 after being stretched)
> > is between 644 and 826 pounds, according to a chart I found on the
> > Internet. Rather than test it empirically with my 16-year-old SUV
> > (no bumper hitch), I wondered what 700 or 800 pounds of shear force
> > would do to an automobile frame, assuming attachment to a suitable
> > bolt somewhere. Or would the tree fall over first?
> >
> > Ted, KN1CBR
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
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> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to [hidden email]
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Vic Rosenthal

Re: DIY Hard-drawn copper wire

In reply to this post by Edward A. Dauer

I have actually done this -- but I didn't drive until it broke. I just
gave it a little stretch. And it wasn't no. 8 wire!
Worked a treat, as our UK cousins say.

73,
Vic, 4X6GP/K2VCO
Rehovot, Israel
http://www.qsl.net/k2vco/

On 11 Feb 2016 16:34, Dauer, Edward wrote:

> In a recent post Jim, K9YC, suggested making hard-drawn copper wire
> for antennas by attaching a few hundred feet of bare copper wire to a
> tree or telephone pole at one end and to a bumper hitch at the other,
> then driving away very slowly until it snaps. That sounded like a
> very attractive idea - much in the ham tradition. I wondered,
> though, whether it could be done using a car without a bumper hitch.
> The minimum breaking strength of number 8 hard-drawn copper wire
> (though it might be closer to number 10 after being stretched) is
> between 644 and 826 pounds, according to a chart I found on the
> Internet. Rather than test it empirically with my 16-year-old SUV
> (no bumper hitch), I wondered what 700 or 800 pounds of shear force
> would do to an automobile frame, assuming attachment to a suitable
> bolt somewhere. Or would the tree fall over first?
>
> Ted, KN1CBR

Bill Frantz

Re: DIY Hard-drawn copper wire

In reply to this post by Edward A. Dauer

Trees are quite strong. When we do demonstrations by breaking
equipment during cave rescue classes, we use trees as anchors
and a truck with an electric winch attached to one tree. Some of
these things break at several thousand pounds force. (We measure
the force with a load cell.)

The basics for tree anchors:

(1) Make sure the tree is alive and healthy.
(2) Wrap the tree with a tarp or heavy cloth to protect its bark
from damage.
(3) Then wrap it with 2" nylon webbing at least 3 times. Use a
water knot to join the webbing. Leave the knot facing the load
and pull the rest of the loops out to a carabiner or quick link
rated for the expected load. This arrangement gives you a chance
of being able to untie the know when you are finished. (2"
tubular webbing is rated at 4000#. If you pull two loops, that
is 4 strands and 16000#. Derate by 50% for knots, bends around
carabiners etc and get 8000#.)
(4) If you are breaking things, such as #8 copper wire, cover
them with blankets to minimize the danger of having them snap
through the air.
(5) Keep everyone far enough away so flying wire won't hit them,
or keep them in a closed vehicle.

73 Bill AE6JV

On 2/11/16 at 6:34 AM, [hidden email] (Dauer, Edward) wrote:

>I wondered what 700 or 800 pounds of shear force would do to an
>automobile frame, assuming attachment to a suitable bolt
>somewhere. Or would the tree fall over first?
-----------------------------------------------------------------------
Bill Frantz | Security is like Government | Periwinkle
(408)356-8506 | services. The market doesn't | 16345
Englewood Ave
www.pwpconsult.com | want to pay for them. | Los Gatos,
CA 95032

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Rick WA6NHC-2

Re: DIY Hard-drawn copper wire

Even the smallest trees have substantial strength, species dependent of
course (some have no tap root and only surface structure). Bind LOW on
the tree to make the pull closest to the anchor of the tree (the roots).

Vehicle frames are much stronger than a piece of typical (for antennas)
copper wire, no worries. Even the smallest car can handle the strain of
a SMALL trailer (or passengers of large girth), BUT one should move
slowly to not shock load the wire or vehicle AND (in addition to the
excellent advice given) the safe zone is any place further away than the
total length of the wire plus at least 20% (factor in stretching) since
it may whip upon snapping. While it's slightly possible that it could
snap in multiple places and become airborne, distance is your friend.
When in doubt, use another tree as a shield PLUS distance and safety
equipment (hard hat, goggles etc.).

Rick nhc

On 2/11/2016 12:13 PM, Bill Frantz wrote:

> Trees are quite strong. When we do demonstrations by breaking
> equipment during cave rescue classes, we use trees as anchors and a
> truck with an electric winch attached to one tree. Some of these
> things break at several thousand pounds force. (We measure the force
> with a load cell.)
>
> The basics for tree anchors:
>
> (1) Make sure the tree is alive and healthy.
> (2) Wrap the tree with a tarp or heavy cloth to protect its bark from
> damage.
> (3) Then wrap it with 2" nylon webbing at least 3 times. Use a water
> knot to join the webbing. Leave the knot facing the load and pull the
> rest of the loops out to a carabiner or quick link rated for the
> expected load. This arrangement gives you a chance of being able to
> untie the know when you are finished. (2" tubular webbing is rated at
> 4000#. If you pull two loops, that is 4 strands and 16000#. Derate by
> 50% for knots, bends around carabiners etc and get 8000#.)
> (4) If you are breaking things, such as #8 copper wire, cover them
> with blankets to minimize the danger of having them snap through the air.
> (5) Keep everyone far enough away so flying wire won't hit them, or
> keep them in a closed vehicle.
>
> 73 Bill AE6JV
>
> On 2/11/16 at 6:34 AM, [hidden email] (Dauer, Edward) wrote:
>
>> I wondered what 700 or 800 pounds of shear force would do to an
>> automobile frame, assuming attachment to a suitable bolt somewhere.
>> Or would the tree fall over first?
> -----------------------------------------------------------------------
> Bill Frantz | Security is like Government | Periwinkle
> (408)356-8506 | services. The market doesn't | 16345 Englewood Ave
> www.pwpconsult.com | want to pay for them. | Los Gatos, CA 95032
>
> ______________________________________________________________
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Jim Brown-10

Re: DIY Hard-drawn copper wire

On Thu,2/11/2016 12:42 PM, Rick WA6NHC wrote:
> BUT one should move slowly to not shock load the wire or vehicle AND
> (in addition to the excellent advice given) the safe zone is any place
> further away than the total length of the wire plus at least 20%

When we've done this, my partner has driven the vehicle and I've been
the observer, carefully out of range. I've never been more than about
100 ft from the wire, and we typically start with about 200 ft. In the
half dozen or so times I've done that, the wire has simply broken
gracefully either near the tree trunk or near the vehicle. What nearly
always happens is that the wire breaks at a point of maximum stretch
along the length. That doesn't mean that it CAN'T snap around, but so
far it has not.

73, Jim K9YC
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Rick WA6NHC-2

Re: DIY Hard-drawn copper wire

I try to not give Murphy any chance, ever, at all. Sometimes that
actually works out. ;-) The tension that is suddenly released, has to
dissipate SOMEwhere, the trick is to not be in the way when that
happens. Copper, because it is soft, uses less energy to stretch, but
... hanging cloths on the wire is good because it's a visual indicator
that the wire is still intact (the cloths are not on the ground) as well
as acting as a shock absorber should the wire fail.

Rick nhc

On 2/11/2016 12:56 PM, Jim Brown wrote:

> On Thu,2/11/2016 12:42 PM, Rick WA6NHC wrote:
>> BUT one should move slowly to not shock load the wire or vehicle AND
>> (in addition to the excellent advice given) the safe zone is any
>> place further away than the total length of the wire plus at least 20%
>
> When we've done this, my partner has driven the vehicle and I've been
> the observer, carefully out of range. I've never been more than about
> 100 ft from the wire, and we typically start with about 200 ft. In the
> half dozen or so times I've done that, the wire has simply broken
> gracefully either near the tree trunk or near the vehicle. What nearly
> always happens is that the wire breaks at a point of maximum stretch
> along the length. That doesn't mean that it CAN'T snap around, but so
> far it has not.
>
> 73, Jim K9YC
> ______________________________________________________________
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kevinr@coho.net

Re: DIY Hard-drawn copper wire

In reply to this post by Edward A. Dauer

From what I can find on the 'net, in my dad's metallurgy manuals, and a
scan of my CRC the ductility of pure copper is 0.62. A piece of copper
wire which is thoroughly annealed will allow stretching of 62% before it
fails at the ductile-brittle transition. This transition point is
temperature dependent so a warmer day is better. Once you have
stretched the copper you can stretch it again as long as you anneal it
first. I did not look up the annealing temperature of copper.

Thus, for safety's sake, stretch the line to a 50% increase or less to
avoid having it part on you. Copper alloys allow for less ductility so
decrease the amount of stretching to avoid an accidental parting.
GL,
Kevin. KD5ONS
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Bernhard.Horst

Microham Microkeyer II, RFI in mike with my K3

In reply to this post by Henry Pollock - K4TMC

Good morning gents...

I have RFI in the mike since using the Microkeyer II from Mikroham.

Mainly on 20m and the lower bands when transmitting with about 700watts and above.

My antenna is about 5meters above the shack on the roof of my house (2 el Ultrabeam), but the effect also can be observed on the lower bands where the vertical is about 12 meters away from the shack. ==> Direct RFI?

I am using the front mike jack on my K3 and Microkeyer

- I have put a capacitor across USB and connector ground in the Microkeyer as recommended by Microham.

- All devices are grounded on common ground and same wall plug.

- I have extra grounded my PCs ground with USB ground as the resistance was not good enough..its now 2 Ohms USB between USB and connector ground. Also recommendation by Microham.

- Bought an extra shielded USB cable and put ferrite cords on.

- Mic line is shielded and ferrite cords in every cable and line

- Common mode chokes at the antenna feedpoint and also at the end of the coax going into the shack.

- Pin 8 of the mike jack is not connected. See http://elecraft.365791.n2.nabble.com/K3-quot-RF-Feedback-quot-and-microHAM-MK2R-or-microKEYER-II-td1080853.html

Microham is stating on their website that it has to do with the wiring of the K3 mike lines in the frontpanel..

I am really lost and helpful for any ideas. Is there an alternative to Microham?

Thinking about going back to my old USB interface, but integration of Radio, Software and Ultrabeam is really nice

We had a similar issue on our clubstation and could cure it with ferrites...on a YAESU rig.

Any hint is appreciated..and thanks for quick feedback as usual.

Already dropped a line to Elecraft support if they have some hints...

I am glad the effect does not show on CW :-)

Many thanks in advance.

Best 73s

Bernie

DL5RDP
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john@kk9a.com

Re: Microham Microkeyer II, RFI in mike with my K3

This week I wired rewired my MicroHAM Micro2R cables for K3S's. As I
recall, I used pin 7 for the mic ground and pin 8 for the PTT ground. In a
brief test it worked ok into a dummy load. Is this not correct?

John KK9A

Bernhard.Horst at bmw.de Bernhard.Horst at bmw.de
Fri Feb 12 01:43:33 EST 2016

Good morning gents...

I have RFI in the mike since using the Microkeyer II from Mikroham.

Mainly on 20m and the lower bands when transmitting with about 700watts
and above.

My antenna is about 5meters above the shack on the roof of my house (2 el
Ultrabeam), but the effect also can be observed on the lower bands where
the vertical is about 12 meters away from the shack. ==> Direct RFI?

I am using the front mike jack on my K3 and Microkeyer

- I have put a capacitor across USB and connector ground in the Microkeyer
as recommended by Microham.

- All devices are grounded on common ground and same wall plug.

- I have extra grounded my PCs ground with USB ground as the resistance
was not good enough..its now 2 Ohms USB between USB and connector ground.
Also recommendation by Microham.

- Bought an extra shielded USB cable and put ferrite cords on.

- Mic line is shielded and ferrite cords in every cable and line

- Common mode chokes at the antenna feedpoint and also at the end of the
coax going into the shack.

- Pin 8 of the mike jack is not connected. See
http://elecraft.365791.n2.nabble.com/K3-quot-RF-Feedback-quot-and-microHAM-MK2R-or-microKEYER-II-td1080853.html

Microham is stating on their website that it has to do with the wiring of
the K3 mike lines in the frontpanel..

I am really lost and helpful for any ideas. Is there an alternative to
Microham?

Thinking about going back to my old USB interface, but integration of
Radio, Software and Ultrabeam is really nice

We had a similar issue on our clubstation and could cure it with
ferrites...on a YAESU rig.

Any hint is appreciated..and thanks for quick feedback as usual.

Already dropped a line to Elecraft support if they have some hints...

I am glad the effect does not show on CW :-)

Many thanks in advance.

Best 73s
Bernie
DL5RDP

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Joe Subich, W4TV-4

Re: Microham Microkeyer II, RFI in mike with my K3

> As I recall, I used pin 7 for the mic ground and pin 8 for the PTT
> ground. In a brief test it worked ok into a dummy load. Is this not
> correct?

That is correct although with the K3/K3S since the Elecraft mic RFI
change it should not matter (both pin 7 and pin 8 are connected to
the "ground" foil on the front panel circuit board).

Early K3 front panels included an RF choke in the mic *and* PTT returns
which made the "pin 1 problem" much worse. With the RF choke removed
(bypassed) the issue is significantly reduced but there may still be a
problem if the overall station installation has any "RF on the coax."

73,

... Joe, W4TV

On 2/12/2016 7:59 AM, [hidden email] wrote:
> This week I wired rewired my MicroHAM Micro2R cables for K3S's. As I
> recall, I used pin 7 for the mic ground and pin 8 for the PTT ground. In a
> brief test it worked ok into a dummy load. Is this not correct?
>
> John KK9A
>
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KEN-3

Re: DIY Hard-drawn copper wire

In reply to this post by Bill Frantz

On 2/11/16 3:13 PM, Bill Frantz wrote:
> (4) If you are breaking things, such as #8 copper wire, cover them
> with blankets to minimize the danger of having them snap through the air.
> (5) Keep everyone far enough away so flying wire won't hit them, or
> keep them in a closed vehicle.

Those are what I was thinking. Be sure to be safely inside the car and
be willing to damage the car.

p.s. I think it's cheaper and better to just purchase harddrawn copper
or copperweld wire. YMMV

Ken WA8JXM
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Grant Youngman

Re: DIY Hard-drawn copper wire

>
> p.s. I think it's cheaper and better to just purchase harddrawn copper or copperweld wire. YMMV
>

It’s hard to disagree with this. I can just see myself with a 100’ of wire tied to my mailbox on one end, pulling the other end down the street on the bumper of my car — wait .. there is no bumper on my car.

I don’t buy Dacron thread and weave my own line, either :-)

Grant NQ5T
K3 #2091, KX3 #8342
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Rick WA6NHC-2

Re: DIY Hard-drawn copper wire

In reply to this post by KEN-3

All true Ron, but remember that copper is only the main element in the alloy at hand.

The one time you take something in safety for granted is the one time it turns on you. It waits...

73,
Rick nhc

Sent from my iPad

> On Feb 13, 2016, at 9:47 AM, Ron D'Eau Claire <[hidden email]> wrote:
>
> Copper is ductile, not elastic. So pulling it will cause it to stretch but
> when it breaks it does not return to its original length releasing a lot of
> energy. It will simply separate at the point of failure, as others noted.
>
> Even so, I am careful any time I'm applying a lot of pressure to anything.
> Murphy reigns supreme over mere mortal Hams.
>
> 73, Ron AC7AC
>
> -----Original Message-----
>
>> On 2/11/16 3:13 PM, Bill Frantz wrote:
>> (4) If you are breaking things, such as #8 copper wire, cover them
>> with blankets to minimize the danger of having them snap through the air.
>> (5) Keep everyone far enough away so flying wire won't hit them, or
>> keep them in a closed vehicle.
>
>
> Those are what I was thinking. Be sure to be safely inside the car and
> be willing to damage the car.
>
> p.s. I think it's cheaper and better to just purchase harddrawn copper or
> copperweld wire. YMMV
>
> Ken WA8JXM
> ______________________________________________________________
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Jim Brown-10

Re: DIY Hard-drawn copper wire

In reply to this post by KEN-3

On Sat,2/13/2016 8:30 AM, Ken wrote:
> p.s. I think it's cheaper and better to just purchase harddrawn copper
> or copperweld wire. YMMV

It's certainly good to see that you guys who have never done it know so
much about how it's done.

And copperweld is a VERY BAD idea.

73, Jim K9YC
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Bernhard.Horst

Re: Microham Microkeyer II, RFI in mike with my K3

In reply to this post by Joe Subich, W4TV-4

Dear all,

just an update..the Microham Microkeyer II has definitely a problem with RF!
I replaced the Microkeyer with a homebrew USB and soundcard interface (Built in 2008) and made new cable distribution box..And the problems are gone.

I have S-NO 280 on the microkeyer..hope the newer ones are better. But definitely not my kind of solution for that cost!

73s
Bernie
DL5RDP

-----Ursprüngliche Nachricht-----
Von: Joe Subich, W4TV [mailto:[hidden email]]
Gesendet: Freitag, 12. Februar 2016 14:15
An: [hidden email]
Betreff: Re: [Elecraft] Microham Microkeyer II, RFI in mike with my K3

> As I recall, I used pin 7 for the mic ground and pin 8 for the PTT
> ground. In a brief test it worked ok into a dummy load. Is this not
> correct?

That is correct although with the K3/K3S since the Elecraft mic RFI
change it should not matter (both pin 7 and pin 8 are connected to
the "ground" foil on the front panel circuit board).

Early K3 front panels included an RF choke in the mic *and* PTT returns
which made the "pin 1 problem" much worse. With the RF choke removed
(bypassed) the issue is significantly reduced but there may still be a
problem if the overall station installation has any "RF on the coax."

73,

... Joe, W4TV

On 2/12/2016 7:59 AM, [hidden email] wrote:
> This week I wired rewired my MicroHAM Micro2R cables for K3S's. As I
> recall, I used pin 7 for the mic ground and pin 8 for the PTT ground. In a
> brief test it worked ok into a dummy load. Is this not correct?
>
> John KK9A
>

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Jim Brown-10

Re: Microham Microkeyer II, RFI in mike with my K3

On Sun,2/14/2016 11:20 PM, [hidden email] wrote:
> just an update..the Microham Microkeyer II has definitely a problem with RF!

Without diving into the details, I helped W6OAT chase down RFI issues in
his station. He had a MicroHam box with an "interface" to the radio that
was a jumble of wires. Virtually NO attention had been paid to the
fundamental concept of a transmission line in the interface between it
and the radio. While that is acceptable at baseband (audio), it is
monumentally foolish when RF is present (i.e. an antenna on the roof).

Current flows in loops, whether at DC or at RF, and the loops form both
antennas and magnetic loops whose coupling is proportional to the loop
area. In the near field, magnetic coupling dominates, so the loop area
can be a VERY big deal. EVERY signal path between devices must be
treated as a transmission line of RFI is a potential issue. That means
EVERY signal path should be a twisted pair or a coaxial pair, so that
the path forms a transmission line. Any interface that does not do this
is an invitation to RFI if the antenna is close enough, or if the power
is high enough, or both.

This is NOT an indictment of Microham -- at a CQP expedition a few years
ago, a team member showed up with an interface betweeen is radio and his
amp to key the amp that was an RCA to RCA cable with a single wire, no
shield. Chassis to chassis was depended on for the return. That works
fine at DC to key the amp, but the resulting current loop area gives
that circuit VERY STRONG coupling to an RF field, both as a magnetic
circuit and as an antenna.

Noted RFI guru Henry Ott talks about understanding where ALL the current
flows, which is revealed by "the hidden schematic lurking behind the
ground symbol" that causes most issues with RFI and crosstalk.

73, Jim K9YC
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Joe Subich, W4TV-4

Re: Microham Microkeyer II, RFI in mike with my K3

In reply to this post by Bernhard.Horst

> just an update..the Microham Microkeyer II has definitely a problem
> with RF!

microKEYER II does not have a problem with RF. You must have an
exceptional problem with common mode RF on your feedline(s) and
that would impact *any* interface in the mic line.

> I replaced the Microkeyer with a homebrew USB and soundcard
> interface (Built in 2008) and made new cable distribution box..And
> the problems are gone.

Unless your homebrew interface includes mic handling circuits with
a wide range preamp, your test in meaningless. Any change in cable
length can make significant differences in RFI as it moves the high
voltage point.

73,

... Joe, W4TV

On 2/15/2016 2:20 AM, [hidden email] wrote:

> Dear all,
>
> just an update..the Microham Microkeyer II has definitely a problem with RF!
> I replaced the Microkeyer with a homebrew USB and soundcard
> interface (Built in 2008) and made new cable distribution box..And
> the problemsare gone.
>
> I have S-NO 280 on the microkeyer..hope the newer ones are better. But definitely not my kind of solution for that cost!
>
> 73s
> Bernie
> DL5RDP
>
> -----Ursprüngliche Nachricht-----
> Von: Joe Subich, W4TV [mailto:[hidden email]]
> Gesendet: Freitag, 12. Februar 2016 14:15
> An: [hidden email]
> Betreff: Re: [Elecraft] Microham Microkeyer II, RFI in mike with my K3
>
>
>> As I recall, I used pin 7 for the mic ground and pin 8 for the PTT
>> ground. In a brief test it worked ok into a dummy load. Is this not
>> correct?
>
> That is correct although with the K3/K3S since the Elecraft mic RFI
> change it should not matter (both pin 7 and pin 8 are connected to
> the "ground" foil on the front panel circuit board).
>
> Early K3 front panels included an RF choke in the mic *and* PTT returns
> which made the "pin 1 problem" much worse. With the RF choke removed
> (bypassed) the issue is significantly reduced but there may still be a
> problem if the overall station installation has any "RF on the coax."
>
> 73,
>
> ... Joe, W4TV
>
>
> On 2/12/2016 7:59 AM, [hidden email] wrote:
>> This week I wired rewired my MicroHAM Micro2R cables for K3S's. As I
>> recall, I used pin 7 for the mic ground and pin 8 for the PTT ground. In a
>> brief test it worked ok into a dummy load. Is this not correct?
>>
>> John KK9A
>>
>

Guy Olinger K2AV

Microham Microkeyer II, RFI in mike with my K3

In reply to this post by Bernhard.Horst

Hi Bernie,

If you are running QRO over your roof, your RFI proofing needs to be
perfect. Your situation is only exceeded in nastiness by being next door to
a 50 kW AM station and maybe not then. Your induced common mode RF
voltages on conductors can be double and triple the desired signal voltages
on the cables and ridiculously more than microphone voltages.

One CAN get lucky and get by, but if one does it's only by dumb blind luck
and any change to cable routing or position and count of station equipment
can disable or polute electronic functions.

If you succumb to the temptation to attribute the changes to the last thing
changed or moved, you will be sent down the rabbit hole to join company
with Alice and the Mad Hatter where nothing makes sense any more. This can
include complaints to manufacturers straight from Wonderland requiring
apologies afterward. Been there, done that. Know whereof I speak.

It is quite probable that replacing the box changed cable specifics. Any
connection that is not a tenth of an ohm or less needs to be replaced or
repaired. I have no idea where you got 2 ohms as a satisfactory connection
resistance. Maybe the USB signal itself will tolerate that under
otherwise non-stressed circumstances but it's far away out of bounds for
RFI proofing.

In your case, QRO on the roof, you need to take maximum anti-RF measures on
**ALL** conductors in the shack. Otherwise just changing orientation of
cables may remove or incite RFI, or worse makes RFI intermittent leading to
suspicions of poltergeist.

I have finally gotten to the point where all retail audio cables need to be
replaced with soldered coax or shielded pairs with WOVEN shields.
ESPECIALLY audio cables terminated in RCA plugs which typically have the
cheapest shields known to man. No retail manufacturer is testing them for
RFI susceptibility in rooftop QRO conditions.

There is a good selection of shielded pair and coax cable with Teflon
dielectric/insulation and woven shields easily soldered to *quality* RCA
plugs or other connectors without melting the wire.

I know that QRO on the roof is all that's available for many folks. Just
understand that's the very stiffest possible demand on all RFI proofing
issues. No cheapies, no short cuts, no omissions allowed in the protocol.

73, Guy K2AV

On Monday, February 15, 2016, <[hidden email]
<javascript:_e(%7B%7D,'cvml','[hidden email]');>> wrote:

> Dear all,
>
> just an update..the Microham Microkeyer II has definitely a problem with
> RF!
> I replaced the Microkeyer with a homebrew USB and soundcard interface
> (Built in 2008) and made new cable distribution box..And the problems are
> gone.
>
> I have S-NO 280 on the microkeyer..hope the newer ones are better. But
> definitely not my kind of solution for that cost!
>
> 73s
> Bernie
> DL5RDP
>
> -----Ursprüngliche Nachricht-----
> Von: Joe Subich, W4TV [mailto:[hidden email]]
> Gesendet: Freitag, 12. Februar 2016 14:15
> An: [hidden email]
> Betreff: Re: [Elecraft] Microham Microkeyer II, RFI in mike with my K3
>
>
> > As I recall, I used pin 7 for the mic ground and pin 8 for the PTT
> > ground. In a brief test it worked ok into a dummy load. Is this not
> > correct?
>
> That is correct although with the K3/K3S since the Elecraft mic RFI
> change it should not matter (both pin 7 and pin 8 are connected to
> the "ground" foil on the front panel circuit board).
>
> Early K3 front panels included an RF choke in the mic *and* PTT returns
> which made the "pin 1 problem" much worse. With the RF choke removed
> (bypassed) the issue is significantly reduced but there may still be a
> problem if the overall station installation has any "RF on the coax."
>
> 73,
>
> ... Joe, W4TV
>
>
> On 2/12/2016 7:59 AM, [hidden email] wrote:
> > This week I wired rewired my MicroHAM Micro2R cables for K3S's. As I
> > recall, I used pin 7 for the mic ground and pin 8 for the PTT ground. In
> a
> > brief test it worked ok into a dummy load. Is this not correct?
> >
> > John KK9A
> >
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

--
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