Re: [Elecraft] Nearby Ham Interference

[Dave Hachadorian]

I have one special low band receive antenna that I need to 
protect.  I use a grain of wheat bulb in series with the antenna 
with two back-to-back 1N5818 Schottky Diodes (low Vf) to ground 
on the receiver side.


You can use a receiver protector on the main TX antenna of a 
transceiver,  but the protector has to go in the RX ANT OUT / RX 
ANT IN loop, and then you have to select RX ANT for receiving.



Dave Hachadorian, K6LL
Yuma, AZ


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Re: [Elecraft] Nearby Ham Interference

[Ian White]

In a multi-transmitter setup, use a simple throwaway RF detector to test
for potentially damaging levels of RF *before* connecting the second
radio. 

The simplest RF indicator consists of a 50-ohm resistor, one diode, one
capacitor and an LED, haywired together on the rear of an SO-239.
Sensitivity depends on the type of detector diode and LED, but typically
the LED will begin to glow at RF levels above a few tens of milliwatts
into 50 ohms. So if the LED shows anything more than a very dim glow, it
would be risky to connect a radio. 

And if the detector burns out, well, that was the whole point of using a
"throwaway" device - to take the bullet instead of your K3! Replace the
damaged parts and carry on testing.

(Obviously there's much more to say about this, but the details are
currently buried in unsearchable Yahoo archives.)


73 from Ian GM3SEK


>-Original Message-
>From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of
>Dave Olean
>Sent: 20 January 2016 06:36
>To: elecraft@mailman.qth.net
>Subject: Re: [Elecraft] Nearby Ham Interference
>
>
>Hello Brendan,
>I have two ten meter 5 el yagi antenna arrays that are just under 300
ft
>apart. One is on a 70 ft tower and consists of three yagis. The other
is a
>single yagi at 30 ft. If the two yagis are boresighted on each other, I
see
>only 17 dB of attenuation between them. I checked the isolation with a
>signal generator and a crystal detector with an HP 415E meter. This can
>blow
>out a front end even running 100 watts. Each yagi has almost 9 dBd gain
in
>free space.  I guess it depends on what ur antenna is, but yagis on the
>higher bands can cause problems when aimed at each other. I did fry one
K3
>using an amp with this setup. I took out a diode.
>Be careful, and make a few checks to avoid surprises.
>Dave K1WHS
>- Original Message -
>From: "Jim Brown" <j...@audiosystemsgroup.com>
>To: <elecraft@mailman.qth.net>
>Sent: Wednesday, January 20, 2016 12:30 AM
>Subject: Re: [Elecraft] Nearby Ham Interference
>
>
>> On Tue,1/19/2016 3:05 PM, Ian wrote:
>>> Consider one of these:http://www.dxengineering.com/parts/dxe-
>rg5000hd
>>
>> The K3 is pretty well protected -- if, for example, you hit it with
too
>> much signal, the attenuator will kick in and the preamp will turn
off. And
>> if that doesn't reduce the signal enough, you'll get a HIGH SIGNAL
warning
>> on your display. In addition to that, there's a diode on the front
end.
>>
>> I'd verify that an RX is getting overloaded before spending dollars
on
>> this product. With antennas 300 ft apart, it's unlikely that you're
going
>> blow anything up unless the other station is running an amp.
>>
>> 73, Jim K9YC
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Re: [Elecraft] Nearby Ham Interference

[Ian]

With this device across the K3's RX in/out ports and RX ANT selected you can
use it with a single TX/RX antenna.  See p.41 of the K3S owner manual.
Works fb, very minimal insertion loss.
73, Ian N8IK 


-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of
j...@kk9a.com
Sent: Tuesday, January 19, 2016 21:58
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Nearby Ham Interference

He said that he has a protector on the Beverage.  The RG5000HD is for
receive antennas only so it will not work when he listens using his TX
antenna on 10m-30m.

John KK9A


Ian ik7565 at verizon.net
Tue Jan 19 18:05:07 EST 2016

Consider one of these: http://www.dxengineering.com/parts/dxe-rg5000hd 

73, Ian N8IK 


-Original Message-
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of
k8kzb at charter.net
Sent: Tuesday, January 19, 2016 08:17
To: 'Elecraft Reflector' 
Subject: [Elecraft] Nearby Ham Interference



My neighbor is a ham, right now I set up a webpage for us to coordinate what
band we are on so that we are not on the same band at the same time. I
originally set this up for field day but it also works good for us.


We are both CW ops and have not ran into issues yet but, there is always a
but, we both want to make sure we do our best to protect our equipment which
we both have K3's.


I have a beverage that i use for 40 through 160 and i have a front end
protector on my rx input but what about 10 theough 30? I have a beam and
rotatable dipole for those bands so how do i protect my receiver better on
those bands?


Our tx antennas are roughly 300 feet apart, he has a vertical right now and
i have both a vertical and a beam to switch between. He plans on a beam this
summer and it will be the same distance apart.


Thoughts...


73,

Jeff K8KZB

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Re: [Elecraft] Nearby Ham Interference

[Charlie T, K3ICH]

I've used a similar (simpler) test fixture which
consisted of a small "grain-of-wheat" bulb,
probably a 5V @ 30 mA, (??) wired directly across
the non-active antenna feed.  A rule-of-thumb is
if you see a glow, you're asking for trouble. 
Watching the bulb connected to a 600' Beveridge,
which is about 50 feet from both a 20-10M Log
Periodic and a 40/60/80/160M dipole, the bulb
would glow at varying intensities when
transmitting up to 100 W on all bands that the
antennas are designed for.  Some bands would show
hardly any glow at 100W but others would light the
lamp to full brightness at < 50 W with no rhyme or
reason to which bands.

It was enough to convince me to either NOT to
leave the Beveridge connected or make sure I had
some sort of protection.  I use a commercial
Collins "Receiver Protector" in line with the wire
which seems to be adequate even running an amp.

73, Charlie k3ICH


-Original Message
From: Elecraft
[mailto:elecraft-boun...@mailman.qth.net] On
Behalf Of Ian White
Sent: Wednesday, January 20, 2016 3:10 AM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Nearby Ham Interference

In a multi-transmitter setup, use a simple
throwaway RF detector to test for potentially
damaging levels of RF *before* connecting the
second radio. 

The simplest RF indicator consists of a 50-ohm
resistor, one diode, one capacitor and an LED,
haywired together on the rear of an SO-239.
Sensitivity depends on the type of detector diode
and LED, but typically the LED will begin to glow
at RF levels above a few tens of milliwatts into
50 ohms. So if the LED shows anything more than a
very dim glow, it would be risky to connect a
radio. 

And if the detector burns out, well, that was the
whole point of using a "throwaway" device - to
take the bullet instead of your K3! Replace the
damaged parts and carry on testing.

(Obviously there's much more to say about this,
but the details are currently buried in
unsearchable Yahoo archives.)


73 from Ian GM3SEK



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Re: [Elecraft] Nearby Ham Interference

[Ian]

Consider one of these: http://www.dxengineering.com/parts/dxe-rg5000hd 

73, Ian N8IK 


-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of
k8...@charter.net
Sent: Tuesday, January 19, 2016 08:17
To: 'Elecraft Reflector' <elecraft@mailman.qth.net>
Subject: [Elecraft] Nearby Ham Interference



My neighbor is a ham, right now I set up a webpage for us to coordinate what
band we are on so that we are not on the same band at the same time. I
originally set this up for field day but it also works good for us.


We are both CW ops and have not ran into issues yet but, there is always a
but, we both want to make sure we do our best to protect our equipment which
we both have K3's.


I have a beverage that i use for 40 through 160 and i have a front end
protector on my rx input but what about 10 theough 30? I have a beam and
rotatable dipole for those bands so how do i protect my receiver better on
those bands?


Our tx antennas are roughly 300 feet apart, he has a vertical right now and
i have both a vertical and a beam to switch between. He plans on a beam this
summer and it will be the same distance apart.


Thoughts...


73,

Jeff K8KZB 



Sent from Outlook Mobile


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Re: [Elecraft] Nearby Ham Interference

[Nels Nelsen]

I have seen how effecttive item #5 is on the previous post.
And if you don't follow  all of Jim's advice then you are really missing
out.
I have seen companies  spend thousands of dollars for advice that you just
got for free.
Nels Nelsen NE7LS

   n_n

And I am still working on #9  (and the rest)
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Re: [Elecraft] Nearby Ham Interference

[Alan]

If you're worried about burning out the receiver front end, why not test 
it?  Add a 20 dB (or more) attenuator in front of the receiver and have 
your neighbor try transmitting on all bands and antennas.  The K3 S 
meter is pretty accurate.  Just add 20 dB to the reading to see how much 
RF is coming down the coax.


Alan N1AL


On 01/19/2016 05:17 AM, k8...@charter.net wrote:



My neighbor is a ham, right now I set up a webpage for us to
coordinate what band we are on so that we are not on the same band at
the same time. I originally set this up for field day but it also
works good for us.


We are both CW ops and have not ran into issues yet but, there is
always a but, we both want to make sure we do our best to protect our
equipment which we both have K3's.


I have a beverage that i use for 40 through 160 and i have a front
end protector on my rx input but what about 10 theough 30? I have a
beam and rotatable dipole for those bands so how do i protect my
receiver better on those bands?


Our tx antennas are roughly 300 feet apart, he has a vertical right
now and i have both a vertical and a beam to switch between. He plans
on a beam this summer and it will be the same distance apart.


Thoughts...


73,

Jeff K8KZB



Sent from Outlook Mobile


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n...@sonic.net


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Re: [Elecraft] Nearby Ham Interference

[Brendon Whateley]

This discussion has made me curious -- especially when I carry my KX3
around at field day -- how much signal is safe and how much can do physical
front end damage?

Brendon KK6AYI


- Brendon

On Tue, Jan 19, 2016 at 10:44 AM, Alan  wrote:

> If you're worried about burning out the receiver front end, why not test
> it?  Add a 20 dB (or more) attenuator in front of the receiver and have
> your neighbor try transmitting on all bands and antennas.  The K3 S meter
> is pretty accurate.  Just add 20 dB to the reading to see how much RF is
> coming down the coax.
>
> Alan N1AL
>
>
>
> On 01/19/2016 05:17 AM, k8...@charter.net wrote:
>
>>
>>
>> My neighbor is a ham, right now I set up a webpage for us to
>> coordinate what band we are on so that we are not on the same band at
>> the same time. I originally set this up for field day but it also
>> works good for us.
>>
>>
>> We are both CW ops and have not ran into issues yet but, there is
>> always a but, we both want to make sure we do our best to protect our
>> equipment which we both have K3's.
>>
>>
>> I have a beverage that i use for 40 through 160 and i have a front
>> end protector on my rx input but what about 10 theough 30? I have a
>> beam and rotatable dipole for those bands so how do i protect my
>> receiver better on those bands?
>>
>>
>> Our tx antennas are roughly 300 feet apart, he has a vertical right
>> now and i have both a vertical and a beam to switch between. He plans
>> on a beam this summer and it will be the same distance apart.
>>
>>
>> Thoughts...
>>
>>
>> 73,
>>
>> Jeff K8KZB
>>
>>
>>
>> Sent from Outlook Mobile
>>
>>
>> __
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Re: [Elecraft] Nearby Ham Interference

[Jim Brown]

On Tue,1/19/2016 3:05 PM, Ian wrote:
Consider one of these:http://www.dxengineering.com/parts/dxe-rg5000hd  



The K3 is pretty well protected -- if, for example, you hit it with too 
much signal, the attenuator will kick in and the preamp will turn off. 
And if that doesn't reduce the signal enough, you'll get a HIGH SIGNAL 
warning on your display. In addition to that, there's a diode on the 
front end.


I'd verify that an RX is getting overloaded before spending dollars on 
this product. With antennas 300 ft apart, it's unlikely that you're 
going blow anything up unless the other station is running an amp.


73, Jim K9YC
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Re: [Elecraft] Nearby Ham Interference

[john]

He said that he has a protector on the Beverage.  The RG5000HD is for
receive antennas only so it will not work when he listens using his TX
antenna on 10m-30m.

John KK9A


Ian ik7565 at verizon.net 
Tue Jan 19 18:05:07 EST 2016

Consider one of these: http://www.dxengineering.com/parts/dxe-rg5000hd 

73, Ian N8IK 


-Original Message-
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of
k8kzb at charter.net
Sent: Tuesday, January 19, 2016 08:17
To: 'Elecraft Reflector' 
Subject: [Elecraft] Nearby Ham Interference



My neighbor is a ham, right now I set up a webpage for us to coordinate what
band we are on so that we are not on the same band at the same time. I
originally set this up for field day but it also works good for us.


We are both CW ops and have not ran into issues yet but, there is always a
but, we both want to make sure we do our best to protect our equipment which
we both have K3's.


I have a beverage that i use for 40 through 160 and i have a front end
protector on my rx input but what about 10 theough 30? I have a beam and
rotatable dipole for those bands so how do i protect my receiver better on
those bands?


Our tx antennas are roughly 300 feet apart, he has a vertical right now and
i have both a vertical and a beam to switch between. He plans on a beam this
summer and it will be the same distance apart.


Thoughts...


73,

Jeff K8KZB

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Re: [Elecraft] Nearby Ham Interference

[Dave Olean]

Hello Brendan,
I have two ten meter 5 el yagi antenna arrays that are just under 300 ft 
apart. One is on a 70 ft tower and consists of three yagis. The other  is a 
single yagi at 30 ft. If the two yagis are boresighted on each other, I see 
only 17 dB of attenuation between them. I checked the isolation with a 
signal generator and a crystal detector with an HP 415E meter. This can blow 
out a front end even running 100 watts. Each yagi has almost 9 dBd gain in 
free space.  I guess it depends on what ur antenna is, but yagis on the 
higher bands can cause problems when aimed at each other. I did fry one K3 
using an amp with this setup. I took out a diode.

Be careful, and make a few checks to avoid surprises.
Dave K1WHS
- Original Message - 
From: "Jim Brown" <j...@audiosystemsgroup.com>

To: <elecraft@mailman.qth.net>
Sent: Wednesday, January 20, 2016 12:30 AM
Subject: Re: [Elecraft] Nearby Ham Interference



On Tue,1/19/2016 3:05 PM, Ian wrote:

Consider one of these:http://www.dxengineering.com/parts/dxe-rg5000hd


The K3 is pretty well protected -- if, for example, you hit it with too 
much signal, the attenuator will kick in and the preamp will turn off. And 
if that doesn't reduce the signal enough, you'll get a HIGH SIGNAL warning 
on your display. In addition to that, there's a diode on the front end.


I'd verify that an RX is getting overloaded before spending dollars on 
this product. With antennas 300 ft apart, it's unlikely that you're going 
blow anything up unless the other station is running an amp.


73, Jim K9YC
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[Elecraft] Nearby Ham Interference

[k8kzb]

My neighbor is a ham, right now I set up a webpage for us to coordinate what 
band we are on so that we are not on the same band at the same time. I 
originally set this up for field day but it also works good for us.


We are both CW ops and have not ran into issues yet but, there is always a but, 
we both want to make sure we do our best to protect our equipment which we both 
have K3's.


I have a beverage that i use for 40 through 160 and i have a front end 
protector on my rx input but what about 10 theough 30? I have a beam and 
rotatable dipole for those bands so how do i protect my receiver better on 
those bands?


Our tx antennas are roughly 300 feet apart, he has a vertical right now and i 
have both a vertical and a beam to switch between. He plans on a beam this 
summer and it will be the same distance apart.


Thoughts...


73,

Jeff K8KZB 



Sent from Outlook Mobile


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Re: [Elecraft] Nearby Ham Interference

[Jim Brown]

On Tue,1/19/2016 5:17 AM, k8...@charter.net wrote:

Our tx antennas are roughly 300 feet apart, he has a vertical right now and i 
have both a vertical and a beam to switch between. He plans on a beam this 
summer and it will be the same distance apart.


Thoughts...


For operation so close together, you really must view this as a multi-op 
station. :) Rules -- very practical ones.


1) Both stations must use rigs with excellent strong signal performance.

2) Both stations must use rigs with very clean TX performance, and 
operate them from supplies of at least 13.8V under load.


3) If using power amps, both stations must tune their amp very carefully.

4) Yes, antenna directivity matters.

At county expeditions for the California QSO Party, we set up three 
stations -- two CW, one SSB, with antennas that are as widely separated 
as possible. Each station is a K3 with new synth board, a KPA500, and a 
KAT500. With 2-el Yagis spaced about 250 ft apart, we can operate CW and 
SSB on the same band with no QRM. The Yagis are carefully located and 
aimed so they are colinear when pointed 70 degrees azimuth (what works 
in W6 for US contests). Our wire antennas for 80 and 40 are about 300 ft 
apart, and we can operate CW and SSB on those bands too.


5) Bandpass filtering helps when you're NOT on the same band. We use 
TXBPF filter sets between the K3s and the KPA500s, and we have 
double-stub notch filters on the 40M and 80M CW feedlines to kill the 
second harmonic of the power amp.


6) Cross polarization can help.

7) Both stations need very good coax with well installed connectors. 
Coax shielding effectiveness depends on a shield with very low 
resistance and very good uniformity. THAT'S why there's no RG8X or RG58 
in my station -- shield resistance is directly related to skin effect, 
and a larger diameter shield has less resistance than a small one.


8) Both stations need very good common mode chokes at the feedpoint of 
their antennas. This prevents radiation and reception by the feedlines.


9) Every little thing matters -- little things add up to a lot. I wasn't 
satisfied with the effectiveness of a 2-stub filter on my 40M antenna -- 
there was still too much second harmonic in my RX on 20M. Last fall, I 
bought some very good coax (Buryflex) and some Amphenol 83-1SP 
connectors and replaced every piece of coax inside my station. I have a 
lot of antenna switching, so that was nearly 100 ft of coax and 50 
connectors. The second harmonic dropped by about 10 dB!


Observations -- the only problem we've ever had with RX burnout was the 
first year we were there -- we strung two dipoles end to end with only a 
few feet between the ends and connected them to different K3s.


73, Jim K9YC
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