Upgrading K3 s/n 11xx to operate on the 472KHz

[Jack Colson]

What needs to be upgraded or added to a stock K3 s/n 11xx to receive/transmit on 472KHz?
Thank you,
73,
Jack, W3TMZ
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[markmusick]

Jack,
This should get you started. This is from the KSYN3A FAQ dated February 13,
2015.

8. What is required to use the 600-meter band?    a. This band is available
in some countries, often on an experimental basis. Specific restrictions may
apply. A K3 fitted with a KSYN3A, as well as a KXV3 and KBPF3A, can receive
signals on this band, and can put out about 1 milliwatt of transmit power.
An external amplifier will be needed, connected to the XVTR OUT jack. At
present we don't have information on such amplifiers. You can also get on
this band using an upconversion transverter whose output is on a low HF band
(also not presently supplied by Elecraft). For a general introduction to the
600-meter band, see:
http://en.wikipedia.org/wiki/600-meter_amateur_radio_band   
   
9. Can a transverter I.F. of "0" be defined as an alternative to setting
CONFIG:KXV3 to TEST?    a. Not at this time, though we hope to add this
capability. Those who frequently alternate between TEST and NOR modes can
assign the KXV3 menu entry to a programmable
function switch, or write a switch macro to change this menu setting as well
as set up the VFO, preamp, etc., for this band.

*** Here is information provided by Wayne in an e-mail to the reflector on
9/16/2017:

Here's some info to get you started on 630 meters with the K3S or K3. For
receive purposes, either transceiver is fully self-contained. For transmit,
you'll need an external amp of some kind.

RECEIVE

The K3S, or a modified K3, will receive on this band via the XVTR IN jack
(or RX ANT IN). You'll need:

  - A KXV3 transverter interface module (standard with the K3S but optional
for the K3)

  - A KBPF3A filter module, or a KBPF3 with a small mod (see KBPF3MDKT). The
KBPF3A mod kit also comes with a capacitor to be installed on the K3's RF
board to suppress LF noise.

RX performance is quite good on 630 meters.

Note: The XVTR IN and RX ANT IN jacks work on 630 meters (472 kHz) because
both are post-TR switch. The TR switch has high-pass filtering that rolls
off starting around 1 MHz, so you can't use ANT 1 or ANT 2.

TRANSMIT

You can get a transmit signal out on 630 meters using the XVTR OUT jack
(same requirements as above). Our initial tests shows about 0.5 milliwatts.
In this case you'd use XVTR IN for receive, not RX ANT IN.

You'll then need an external amplifier. It could be keyed using the rig's
KEY OUT jack. This signal could also be used to control a T/R switch if you
needed to use the same antenna for both transmit and receive. If you use two
different antennas, you'll still have to cut the RX antenna off during TX,
most likely.

Firmware configuration:

To use XVTR IN and OUT on this band, set up the radio for 160 meters, then
set the CONFIG:KXV3 menu entry to TEST. This is necessary because 160 meter
isn't available as a transverter IF selection (yet).

73,
Wayne
N6KR


Mark, WB9CIF    

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Jack Colson
Sent: Sunday, October 1, 2017 10:59 PM
To: [hidden email]
Subject: [Elecraft] Upgrading K3 s/n 11xx to operate on the 472KHz

What needs to be upgraded or added to a stock K3 s/n 11xx to
receive/transmit on 472KHz?
Thank you,
73,
Jack, W3TMZ
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[Don Wilhelm]

Jack,

You will need the new synthesizer - two if you have the KRX3.
You will also need the KBPF3A.  If you already have a KBPF3, there is an
upgrade kit that you can install - the KBPF3MDKT (see K3 Parts and Mod
Kits).
You will also need the KXV3 (or KXV3A or KXV3B) option in your K3
because the antenna must connect to the RX ANT IN or XVTR IN.  Transmit
is on the KXV3 XVTR OUT jack - you will need an amplifier because the
output is low level (none sold by Elecraft).

73,
Don W3FPR

On 10/1/2017 6:58 PM, Jack Colson wrote:
> What needs to be upgraded or added to a stock K3 s/n 11xx to receive/transmit on 472KHz?
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[Edward R Cole]

I used my K3 on 495-502 KHz as an experimental station.  I got 1mw
output at the XVT Tx output jack running the TEST mode.

For amplifier, I bought a surplus Southern Avionics NDB (aircraft Non
Directional Beacon) transmitter.  It is a xtal controlled oscillator
amplified to 100w into 50-ohm load.  25w and 50w NDB's were also
made.  Check surplus electronic sales for them.  I suspect the supply
will be small and quickly disappear once discovered by new 630m hams.

Using with the K3, I removed the oscillator ckts and used a 0.1 mfd
disc ceramic cap to couple from coax to the bandpass filter (single
slug-tuned coil which feeds a 2N2222 pre-driver (about 10mw
output).  I disconnected the internal antenna loading coil and
switched the multi-tapped output coupling coil to 50-ohms.

You will need to build a base loading coil for using a very-short
vertical antenna (if you have one for 160m, just substitute the loading coil).

630m is brand new ham radio country so prepared to design, modify,
and build some of your equipment and antennas.  Or wait a year or so
as small mfr's will likely show up or start up providing gear.

I should have approval by Oct. 15 to start on 472-479 KHz.  I plan to
use CW/psk31/FT8 as ham modes and run an APRS beacon on 471-KHz as
WD2XSH/45 under the old ARRL Experimental License.  Many of us are
looking to run beacons around 471-KHz just outside the new 630m Ham
Band (only legal if you hold an experimental license).

73, Ed - KL7UW
   http://www.kl7uw.com
Dubus-NA Business mail:
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