[Elecraft] XV144

[Pierre-François (f5bqp_pfm)]

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Message: 16
Date: Sun, 05 Jul 2015 14:14:52 -0800
From: Edward R Cole<kl7uw at acsalaska.net>
To:Elecraft at mailman.qth.net
Subject: Re: [Elecraft] XV144 transverter firmware
Message-ID:<201507052214.t65MEr70028335 at mail41c28.carrierzone.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

Pierre-Francois, F5BQP:

Substituting the xtal LO with a PLL will solve the frequency drift
issue.  One caveat is making sure the PLL has low phase-noise as that
affects ability to handle strong adjacent frequency signals when
trying to copy weak signals (which is why you are using JT65).  One
of the shining parameters of the K3 design.

I had DEMI transverters long before I acquired my K3/10 (and KX3) so
have continued to use them.  I have heated xtal osc on 144 and 222
but use a PLL on 432, 1296, and 3400 MHz.  Recent re-design by DEMI
has improved xtal LO frequency stability while the xtal oscillator
has excellent phase-noise performance.  I see about 7 to 10 Hz drift
on the 101 to 194 MHz xtal oscillators in the new L-series of DEMI
transverters.  But LO's for higher bands multiply the xtal oscillator
frequency which also multiplies drift.

For 432 and higher I found using the N5AC ApolLO PLL's worked well in
DEMI transverters.  The N5AC Apol series is not the lowest in
phase-noise so that could be a real concern for those doing VHF-plus
in high density RF environments.  So  one should consider phase-noise
when deciding on a PLL.  W1GHZ has a new VCXO design that exhibits
lower noise than a PLL. Of course this is for the experimenter ham who DIY.

I do think there will be a increasing use of PLL in VHF and higher
equipment due to demands of digital modes and need for better
frequency stability on the higher bands.

One issue is the need for an external 10-MHz reference.  That is not
hard to embed into current equipment.  I did that for a 432-MHz
transverter customer.

73, Ed - KL7UW
http://www.kl7uw.com
      "Kits made by KL7UW"
Dubus Mag business:
      dubususa at gmail.com







Hi Ed,

For this improvement I've an EXCELLENT PLVCXO 116MHz which is used intensively in Eu by microwavers, the PN is excellent, even more, I've measured it very recently with an APPH AnaPico source analyser ( www.anapico.com ) .
I'm going to build an external enclosure box where I'll include the 116MHz LO for the XV144, the 404MHz LO for the XV432 and a small internal 10MHz distribution amplifier .
I'll not remove the existing LO of the XVs, just two SMB bulkhead on the back panel for the in/out LO (SMA are too large for the remaining space), so it would be possible with a small smb jumper to come back to the original LO.
There is not enough space inside the XV box to include the PLLCXO without depopulating the initial oscillator, and I don't want to do it.

Will need to know the RAL paint number of the XV enclosures, if someone knows it I will appreciate.
I would have preferred a XV empty enclosure but I doubt I could purchase one to ELECRAFT so I'll repaint my own enclosure (will not purchase another XV just for the box... Lol...)

Concerning the 10MHz most of my radio equipment are driven with the same GPSDO 10MHz distributed from the cellar to the tower for microwave transverters going to be installed soon on the tower itself and to the shack for the radios. The lab has another GPSDO or a rubidium PRS10.


Best 73's
Pierre-Francois, F5BQP




  

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