[Elecraft] Boots for the XG3...

[Joe Subich, W4TV]

 > Let the guys play with their XG3 with 0 dBm...best approach.

0 dBm is fine but I certainly would not want my neighbor putting a
1W XG3 into a decent (0 dBi) antenna - his Icom 746 is already a
terrible phase noise generator.  At 1W the calculation for the XG3
at 1 mile in a 500 Hz bandwidth at 14 MHz is roughly:

    +30 dBm (1W) - (105 dBC/Hz - 10*log(500)) - 60 dB (path loss)

With net antenna gain of 0dB, that's about -107 dBm on 20, go down
to 160 and it is around -90 dBm and go up to 6 and it drops to about
-118 dBm.  The situation at 160 may not be quite that bad but it
might be worse on six because of the net antenna gain factors.  In
any case, the noise for an XG3 amplified to 1W at 1 mile is well
above the ambient noise level - even a for multiband vertical in my
semi-rural/suburban area.

The hard numbers make it clear that 0 dBm is about the limit for an
XG3 into a "real" antenna!

73,

    ... Joe, W4TV


On 6/27/2011 5:12 PM, Edward R. Cole wrote:
> Joe,
>
> NO worries. I was just testing the waters to see if there *any*
> interest. I would have to build a prototype and test it before offering
> anything publicly. One might have to decide on a beacon frequency and
> build a multi-pole xtal filter to take care of phase noise or maybe use
> the XG3 in a PLL that would clean up the phase noise. Just about any
> approach seems a lot of work just to use the XG3. Most likely one is
> better building a clean beacon from scratch.
>
> Let the guys play with their XG3 with 0 dBm...best approach. I have used
> mine on 432 and 1296 as a test signal for my eme dish and placed it up
> to 200-foot from the dish. Using a 6-dB log-periodic antenna and 15-dB
> attenuators. Theoretically the XG3 outputs 1/n above 200-MHz (432 = -4.8
> dBm; 1296 = -9.5 dBm, assuming it is running at Fo=144 and n=3 or 9) I
> even pointed the log-periodic away from the dish to obtain a weaker
> signal. The dish has 34.5 dBi gain on 1296.
>
> I have a 144-MHz and 10-GHz dual beacon half-finished that runs with a
> TCXO for 10-GHz and xtal osc for 2m. Basically it is a 144/10,368
> transverter with 20-dB directional coupler to tap off 20mw 144-MHz for
> driving the transverter and 2w going to a omni-directional 2m antenna.
> The transverter should provide 100-125mw output to a multi-slot
> waveguide radiator for about 1/2w ERP on 10-GHz. I also have a 1w amp to
> boost the 10-GHz output.
>
> 73, Ed
>
> At 06:32 AM 6/27/2011, you wrote:
>
>> *PLEASE DO NOT* move forward with *any* amplifier for the XG-3.
>>
>> Like John Ragle I have looked at the phase noise from my XG-3 and it
>> is completely unsatisfactory for beacon use. At -33 dBm it raises the
>> receiver noise floor by more than 20 dB when measured at + 100 KHz on
>> 28 MHz and + 250 KHz in 50 MHz. The measured noise floor (MDS) is more
>> than -110 dBm and at 10W, the XG-3 would make an excellent jamming
>> device.
>>
>> When used as a beacon at even *ONE WATT* the required path loss would
>> need to be around 100 dB for the phase noise to be below the receiver
>> noise level and would still need to be 80 dB or more to be below the
>> local noise level on a "quiet" band.
>>
>> If "boots" become common for the XG-3, I would urge Wayne to remove
>> the beacon capability from the XG-3.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 6/27/2011 2:05 AM, Edward R. Cole wrote:
>>> I obtained some 7-pole LP filters from Coilcraft:
>>> http://www.coilcraft.com/lcfilt.cfm
>>> http://www.coilcraft.com/pdf_viewer/showpdf.cfm?f=pdf_store:lcfilt.pdf
>>> cost $3.00 in single quantities.
>>>
>>> This would take care of harmonic suppression. I have five of these
>>> for different frequencies but have been working on other projects so
>>> have not measured them using the XG3. I intend to install mine in
>>> 1-inch copper pipe with BNC connectors for better isolation at very
>>> weak signal levels, but that would not be needed if incorporated into
>>> a beacon amplifier. The easiest approach for that is using mmics and
>>> RF modules that are 50-ohm in/out. All that is required is some dc
>>> bias and some RF bypassing of the dc lines.
>>>
>>> This is probably more appropriate for a third party than
>>> Elecraft. I'm guessing it would be a low volume item.
>>>
>>> I proposed the MAR-6 plus M57735 to John Ragle. The M57735 costs
>>> $67.75 from RFParts.
>>> http://www.rfparts.com/pdf_docs/57704-68776/57735.pdf
>>> The M57735 is rated 17w out for 200mw in, so with 20mw drive one
>>> might get 1.7w (gain = 25 dB with 10mw drive).
>>> The MAR-6 are about $5 and will provide about 16-18dB gain with 0dBm
>>> input.
>>>
>>> Add filter, misc components, connectors, pcb, and enclosure and it is
>>> looking like about $100 without labor to assemble it. Someone
>>> offering this as a kit would probably want another 25% markup for
>>> their time. Add $12 for flat-rate shipping.
>>>
>>> How many folks would order a kit?
>>>
>>>
>>>
>>> 73, Ed - KL7UW, WD2XSH/45
>>> ======================================
>>> BP40IQ 500 KHz - 10-GHz www.kl7uw.com
>>> EME: 50-1.1kw?, 144-1.4kw, 432-100w, 1296-60w, 3400-?
>>> DUBUS Magazine USA Rep dubususa at gmail.com
>>> ======================================
>>>
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>>
>>
>> 73, Ed - KL7UW, WD2XSH/45
>> ======================================
>> BP40IQ 500 KHz - 10-GHz www.kl7uw.com
>> EME: 50-1.1kw?, 144-1.4kw, 432-100w, 1296-60w, 3400-?
>> DUBUS Magazine USA Rep dubususa at gmail.com
>> ======================================
>
>