[NLRS] DEMI 10 GHz Transverter Question

[Donn Baker - WA2VOI/0]

Hi Scott.

Personal experience and opinion, obviously.

I have the 5mw version with the 2 (3) W amplifier externally mounted.  The LO drift IS noticably less than others with 
the amplifier mounted intenally.  This problem could be removed with the new option DEMI is just now offering (A32) 
which is a DDS/PLL synthesizer that replaces the current MICROLO XTAL oscillator.  The A32 can be set for the LO 
frequency of ANY of the DEMI microwave XVRTRs and for many different i.f. schemes.  IF (and I do say if) the phase noise 
it produces is acceptable, it will do two things: get the XVRTR to within a kHz or so of the correct frequency, and be 
relatively insensitive to temperature changes.  The A32 requires an external 10MHz reference oscillator.  The better the 
10MHz reference, the better the LO frequency will be.

The A32s are not in general use yet... I have one on order (as do several of us) and its on its way.  I MAY have it 
before the September Weekend of the 10GHz Contest.  That will be a chance to see if the phase noise is OK.  Both the 
developer (Steven Hicks, N5AC) and DEMI feel that it will be acceptable.

When ordered with the XVRTR, it replaces the MICROLO and is about the same price as a MICROLO.  You will need to add a 
10MHz TCXO or OCXO which can cost anywhere from $25 to $200.  GPS-disciplined OCXOs are of course the best, but also the 
most expensive.

You should look at the DEMI web pages and read the stuff about the A32 before you make a decision.

Again, opinion: IF the phase noise is OK (and I strongly suspect that it will be), the A32 is the way to go.  On 
frequency (OK, with in 5-6 KHz with a cheap 10MHz TCXO and maybe >200 Hz with a good OCXO or disciplined 10MHz source) 
AND little or no temperature drift.

FWIW

73 Donn
WA2VOI/0

Microwave Update '08
October 17-18, 2008
www.microwaveupdate.org

----- Original Message ----- 
From: "Scott" <acepilot at bloomer.net>
To: "NLRS List" <nlrs at mailman.qth.net>; "Chippewa Valley VHF" <cvvhf at cvvhf.org>
Sent: Thursday, September 04, 2008 12:09 AM
Subject: [NLRS] DEMI 10 GHz Transverter Question


>
>
> Question for those in the know (experience with these units)...
>
> I am going to buy a 10 GHz transverter from DEMI (hopefully pick it up at MUD) and have a question as to which would 
> be the preferred choice...
>
> I am going to BUILD, not buy.  I can go with the 3W kit that has the PA built into the transverter box or I can build 
> the 5 mW basic transverter and build the separate PA module.  I'm leaning toward the separate PA module to keep heat 
> changes within the transverter box to a minimum to minimize any drift.  Pros?  Cons?
>
> -- 
> Scott N0EDV
> http://corbenflyer.tripod.com/
> Flying Corben Junior Ace - Building RV-4
> Gotta Fly or Gonna Die
>
>
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