[Elecraft] 500 kHz Transceive Operation With the K3

[Mike-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