500 kHz Transceive Operation With the K3

[wayne burdick]

A few countries allow experimental amateur radio operation in the 500
kHz band (600 meters). This is a fascinating and historic band that is
used for beacons and ground-wave communications. For hams, there are
very specific mode and power restrictions, and an experimental license
may be required. In the U.S., see http://www.500kc.com/ and
http://www.arrl.org for the latest news.

The K3 can be used for both receive and transmit on this band as
explained below.


500 kHz Receive-Only Operation
------------------------------

The K3 can receive signals in the 500-kHz band if both the KXV3 and
KBPF3 modules are installed.

The KXV3 (RF I/O module) is needed because it provides an RX ANT IN
jack. This jack bypasses the high-pass filter in the normal receive
antenna path. At 500 kHz, the high-pass filter--which protects the T/R
PIN diodes--will attenuate signals by about 20 dB. There is no such
attenuation at 500 kHz when using the RX ANT IN jack, and sensitivity
is excellent. We measured an MDS of -133 dBm with preamp OFF and a DSP
filter bandwidth of 50 Hz.

The KBPF3 (general-coverage module) is needed because the normal
160-meter band-pass filter covers only about 1.7 to 2.1 MHz. The KBPF3
includes a low-pass filter that passes signals down to 500 kHz with
very little attenuation.

A low-noise receiving antenna is recommended for use at 500 kHz.

Diversity receive should be very useful at 500 kHz. To do this, you'll
need a sub receiver (KRX3) that is equipped with its own KBPF3 module.
You'll also need a separate receive antenna for the sub, oriented
differently from the receive antenna used with the main receiver.


500-kHz Transmit/Receive Operation
----------------------------------

The K3 cannot be used to directly transmit on 500 kHz at high power.
The low-pass filter cutoff frequency is well above that needed for
attenuation of harmonics on this band, and other components in the
transmit path are optimized for 1.8 MHz and higher.

However, the K3 can put out a clean 500 kHz signal of about 0.5
milliwatts at the XVTR OUT jack (on the KXV3). This can be fed to an
external amplifier (this is left as an exercise for the reader).
Transmit power is restricted on this band, and is usually expressed as
ERP (Effective Radiated Power). This means you can use high power to
make up for the use of an electrically short antenna. Since 1/4
wavelength at 500 kHz is about 468 feet, not many hams will be using a
full-length vertical or dipole.

As with receive, transmit at 500 kHz requires the KXV3 and KBPF3
modules. In this case, though, you'll need to use the XVTR IN and XVTR
OUT jacks, with XVTR IN going to the receive antenna, and XVTR OUT
going to your 500 kHz amplifier and a transmit antenna. If the same
antenna is used for both transmit and receive, an external T/R switch
will also be needed, controlled by the K3's KEY OUT signal. If separate
transmit/receive antennas are used, it may be necessary to provide a
PIN-diode switch to open or short the receive antenna during transmit.
The XVTR IN jack is normally used with a transverter, so it doesn't
have such protection built in.

IMPORTANT: In order to transmit at 500 kHz via the XVTR OUT jack, you
must set CONFIG:KXV3 to TEST. This routes all signals through XVTR IN
and XVTR OUT, which is why the receive antenna must be connected to
XVTR IN in this case. (You can't use XVTR OUT for transmit and RX ANT
IN for receive due to switching limitations.) Be sure to set KXV3 back
to NOR when using normal ham bands.

If interest in the 500-kHz band is sufficient, we'll change add 160
meters as an IF band for use with transverters. This would allow you to
set up a 500 kHz transverter band, so it would not be necessary to set
KXV3 to TEST.


Synthesizer Considerations
--------------------------

Before using 500 kHz, you'll need to make sure your synthesizer is
adjusted to cover this band. Tap DISP and use VFO B to locate the
"PLL1" display. If the voltage is less than 0.9 V when VFO A is set,
contact customer support for suggestions on how to adjust it. If you
plan to transmit on this band, connect an short (3') antenna to the
XVTR OUT jack and listen to your signal with another 500 kHz receiver.
Make sure the signal sounds clean.


73,
Wayne
N6KR


----

http://www.elecraft.com

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[WE0H]

Excellent news Wayne. I will forward this to our 600 meter email reflector.

Is there any way possible that you can do a similar mod for the K2 to
make it transmit on 600 meters? Our new band that we should be granted
will be 495kc-510kc. Of course that is a Part 5 Experimental band thus
far. The ARRL will be working with the FCC down the road to see if they
can turn this into a Amateur Radio Band.

Many thanks,

--
Mike
WE0H
WD2XSH/16 on 600m
WD2XGI on 1750m & 2200m
K2 #6698



wayne burdick wrote:

> A few countries allow experimental amateur radio operation in the 500
> kHz band (600 meters). This is a fascinating and historic band that is
> used for beacons and ground-wave communications. For hams, there are
> very specific mode and power restrictions, and an experimental license
> may be required. In the U.S., see http://www.500kc.com/ and
> http://www.arrl.org for the latest news.
>
> The K3 can be used for both receive and transmit on this band as
> explained below.
>
>
> 500 kHz Receive-Only Operation
> ------------------------------
>
> The K3 can receive signals in the 500-kHz band if both the KXV3 and
> KBPF3 modules are installed.
>
> The KXV3 (RF I/O module) is needed because it provides an RX ANT IN
> jack. This jack bypasses the high-pass filter in the normal receive
> antenna path. At 500 kHz, the high-pass filter--which protects the T/R
> PIN diodes--will attenuate signals by about 20 dB. There is no such
> attenuation at 500 kHz when using the RX ANT IN jack, and sensitivity
> is excellent. We measured an MDS of -133 dBm with preamp OFF and a DSP
> filter bandwidth of 50 Hz.
>
> The KBPF3 (general-coverage module) is needed because the normal
> 160-meter band-pass filter covers only about 1.7 to 2.1 MHz. The KBPF3
> includes a low-pass filter that passes signals down to 500 kHz with
> very little attenuation.
>
> A low-noise receiving antenna is recommended for use at 500 kHz.
>
> Diversity receive should be very useful at 500 kHz. To do this, you'll
> need a sub receiver (KRX3) that is equipped with its own KBPF3 module.
> You'll also need a separate receive antenna for the sub, oriented
> differently from the receive antenna used with the main receiver.
>
>
> 500-kHz Transmit/Receive Operation
> ----------------------------------
>
> The K3 cannot be used to directly transmit on 500 kHz at high power.
> The low-pass filter cutoff frequency is well above that needed for
> attenuation of harmonics on this band, and other components in the
> transmit path are optimized for 1.8 MHz and higher.
>
> However, the K3 can put out a clean 500 kHz signal of about 0.5
> milliwatts at the XVTR OUT jack (on the KXV3). This can be fed to an
> external amplifier (this is left as an exercise for the reader).
> Transmit power is restricted on this band, and is usually expressed as
> ERP (Effective Radiated Power). This means you can use high power to
> make up for the use of an electrically short antenna. Since 1/4
> wavelength at 500 kHz is about 468 feet, not many hams will be using a
> full-length vertical or dipole.
>
> As with receive, transmit at 500 kHz requires the KXV3 and KBPF3
> modules. In this case, though, you'll need to use the XVTR IN and XVTR
> OUT jacks, with XVTR IN going to the receive antenna, and XVTR OUT
> going to your 500 kHz amplifier and a transmit antenna. If the same
> antenna is used for both transmit and receive, an external T/R switch
> will also be needed, controlled by the K3's KEY OUT signal. If separate
> transmit/receive antennas are used, it may be necessary to provide a
> PIN-diode switch to open or short the receive antenna during transmit.
> The XVTR IN jack is normally used with a transverter, so it doesn't
> have such protection built in.
>
> IMPORTANT: In order to transmit at 500 kHz via the XVTR OUT jack, you
> must set CONFIG:KXV3 to TEST. This routes all signals through XVTR IN
> and XVTR OUT, which is why the receive antenna must be connected to
> XVTR IN in this case. (You can't use XVTR OUT for transmit and RX ANT
> IN for receive due to switching limitations.) Be sure to set KXV3 back
> to NOR when using normal ham bands.
>
> If interest in the 500-kHz band is sufficient, we'll change add 160
> meters as an IF band for use with transverters. This would allow you to
> set up a 500 kHz transverter band, so it would not be necessary to set
> KXV3 to TEST.
>
>
> Synthesizer Considerations
> --------------------------
>
> Before using 500 kHz, you'll need to make sure your synthesizer is
> adjusted to cover this band. Tap DISP and use VFO B to locate the
> "PLL1" display. If the voltage is less than 0.9 V when VFO A is set,
> contact customer support for suggestions on how to adjust it. If you
> plan to transmit on this band, connect an short (3') antenna to the
> XVTR OUT jack and listen to your signal with another 500 kHz receiver.
> Make sure the signal sounds clean.
>
>
> 73,
> Wayne
> N6KR
>
>
> ----
>
> http://www.elecraft.com

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[wayne burdick]

Mike-WE0H wrote:

> Excellent news Wayne. I will forward this to our 600 meter email
> reflector.
>
> Is there any way possible that you can do a similar mod for the K2 to
> make it transmit on 600 meters?

The K2's synthesizer won't go low enough in frequency. You could
probably modify it, but I haven't tried this.

73,
Wayne
N6KR

---

http://www.elecraft.com

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[AC7AC]

CONTENTS DELETED

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[wayne burdick]

The present limit is 500 kHz. I could probably move it down a little,
but not to 400 -- the synth won't go that low.

73,
Wayne
N6KR

Ron D'Eau Claire wrote:

> Am I missing something, or is the K3 capable of going below 500 kHz?
>
> 500 kHz is near the top of the 600 meter "marine" band which extends
> down
> nearly to 400 kHz (IIRC 426 kHz is a popular frequency).

---

http://www.elecraft.com

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[WE0H]

See if you can make it go to 495.000kc as that is the bottom end of any
possible Amateur Band. If it can tune 495.000kc thru 515.000kc, that
should cover any future Amateur 600m band. There are currently
Experimental stations using that spectrum and Amateur Bands in other
countries. The band coverage varies by country but is within that window
worldwide.

Mike
WE0H


wayne burdick wrote:

> The present limit is 500 kHz. I could probably move it down a little,
> but not to 400 -- the synth won't go that low.
>
> 73,
> Wayne
> N6KR
>
> Ron D'Eau Claire wrote:
>
>> Am I missing something, or is the K3 capable of going below 500 kHz?
>>
>> 500 kHz is near the top of the 600 meter "marine" band which extends
>> down
>> nearly to 400 kHz (IIRC 426 kHz is a popular frequency).
>
> ---
>
> http://www.elecraft.com

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[Rick Dettinger-3]

On Jun 10, 2009, at 2:20 PM, Mike-WE0H wrote:

> See if you can make it go to 495.000kc as that is the bottom end of  
> any
> possible Amateur Band. If it can tune 495.000kc thru 515.000kc, that
> should cover any future Amateur 600m band. There are currently
> Experimental stations using that spectrum and Amateur Bands in other
> countries. The band coverage varies by country but is within that  
> window
> worldwide.
>
The main tuning stops at 500.000 khz but I was able to get the display  
down to 490.001 khz with the RIT on receive.  Finally, I have found a  
use for my RIT control.  Now, I just need to find a use for my Memory  
buttons (:.

73,
Rick   K7MW
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