[Elecraft] 630 MHz transmit and receive using the K3s or modified K3

[Wayne Burdick]

Thanks for the info, Ed. I'm going to have to figure out my own antenna for this band. 

Wayne
N6KR

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http://www.elecraft.com

> On Sep 17, 2017, at 12:01 PM, Edward R Cole <kl7uw at acsalaska.net> wrote:
> 
> Thanks Wayne.
> 
> I have been using my K3 (SN 4043) purchased in 2010 on 495 to 502 KHz from 2012 as part of the ARRL Experimental 500-KHz Group using experimental license WD2XSH/45.  Primarily using std CW or WSPR at about 4w ERP.  Our experimental license specified using power up to 20w ERP so one had to calculate from EIRP.
> 
> New ham regs now use EIRP which is typically shown if modeling an antenna using EZNEC.  I modeled my 43-foot high by 122-foot long inverted-L which results in impedance at 503-KHz of Z = 0.83 - j886.5.  I measured the antenna using my modified MFJ-269B at 18 - j0 after adjusting the base loading coil for resonance.
> 
> Then get total radiated power from TPR = 0.83/18 * 100 = 4.6w  (note my amplifier is running 100w into 50-ohm load).
> From EZNEC-5 antenna gain = 1.48 , EIRP = 4.6 * 1.48 = 6.8w
> ERP = 6.8/1.64 = 4.15w.  Thus my antenna efficiency is only 4%.
> 
> My unmodified K3 will only operate down to 490-KHz but I have the new synth board and mod kit for the KBPF3 to install which will extend operation to the new 630m band (472-479 KHz).  I was able to get 1mw output with my unmodified K3 in TEST which I drove a modified NDB transmitter to 100w.  The NDB is an aircraft CW beacon with dual xtal LO separated by 400-Hz.  By CW keying that shift it produced a mcw signal.  I removed he LO and simply capacitively couple about 0.1 mw to fully drive the three stage amplifier.  I was able to pick up the NDB surplus for $40 which is self-contained with 55v PS.  I expect them to quickly be snatched up by 630 ops.
> 
> I home made a 10-inch by 11-inch base coil wound 1/4 inch spacing on a plastic form to provide loading.  I have two taps which are moved between winter and summer soil conditions which shift the ground resistance enough to shift resonant frequency.  I got about 5-Hz SWR bandwidth.
> 
> Previous to the new mods, I ran a SDR-IQ receiver and only transmitted with the K3.  I have picked up the CW signal from an Oregon station and my signal has been detected as far as Buffalo, NY.
> 
> AFAIK only two commercial radio will operate on our new ham band:  K3s (and mod K3) or theTS590.  This opens a market for entrepreneurs to provide preamps, amplifiers and transverters.  Puts Elecraft ahead of the "crowd", again!
> 
> NOTE:  FCC requires pre-registering with UTC before operating on 630m.  Its a 30-day process.  I'm waiting for my approval.
> 
> 
> 
> 73, Ed - KL7UW
>  http://www.kl7uw.com
> Dubus-NA Business mail:
>  dubususa at gmail.com 
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