[NLRS] Advice on 2M transverter, bricks

[Dr. Gerald N. Johnson]

On Sun, 2007-02-25 at 22:57 -0600, Cathy James wrote:
> 
> 
> With spring approaching (hard as it may be to believe under all that 
> snow), I'm starting to plan my 2M weak-signal station.  Some of you may 
> remember that I've asked about transverters and rigs in the past.
> 
> eHam has very mixed reviews of the Down East Microwave 60W 2M 
> transverter.  Elecraft's XV144 has superb reviews, but is only 20W.  I 
> think the prices are similar.

Going with a 10 watt transverter fits more PAs that need 10 watts of
drive for 100 watts or more. 60 watts will way overdrive most bricks and
gain little but splatter. But I'm using an FT-857 at 50 watts and
working out well until my antenna rotor was eaten by the rotor.
> 
> For those of you who do moderately serious weak-signal CW and SSB work 
> with a 3-element beam or less, what power do you find to be necessary?  
> Will I need a brick behind the XV144 if I go that route?  What are some 
> models of brick that are affordable and _readily available_?  I'm not 
> interested in purchasing anything off of eBay or spending a year 
> prowling hamfests hoping to find a particular model.
> 
> I would probably experiment with both my Uniden HR2600 and K2 to see how 
> much difference the receiver makes.  I presume that I need to build the 
> XV60 interface for the K2 to do this?

The K2 surely is a far superior receiver for both noise and intermod
when the band is busy.
> 
> I'm currently building a 3-element quad from PVC and copper tubing, and 
> hoping to get within sight of the theoretical gain for this design (9 
> dB+).  Is this a reasonable gain figure for weak-signal, or am I going 
> to find that everyone else is running 5 or 6 element beams?

Might as well keep that under the bed. Most weak signal stations are
running 1 to 4 12 to 15 element yagis. at least 12 dBd gain. 9 dB from a
3 element is not realizable, not even dBi. And a quad has a strong cross
polarized response about 45 degrees from the main lobe that leads to
much interference from vertically polarized services like pages and
repeaters.

There is another concept proposed and used by K1WHS, he calls it the
large vertical array. Its a stack of 4, 8, or 16 short yagis. The yagis
are selected (5 elements, 9.1 dBd claimed) for a 10 dB beam width of 90
degrees. Four stacked (5.5' spacings, so taking 16.5' of tower space)
gives nearly 15 dBd gain in the main lobe, comparable to a 5 wavelength
long boom yagi and much easier on the rotor. I tested one of the yagis
at the last CSVHF conference and it was a tiny bit above 9.1 dBd. There
are some articles on the LVA at www.directivesystems.com
> 
> Are many weak-signal ops running CW, or is most of the operation SSB 
> these days?  I think CW will be much easier than SSB if I'm not running 
> a mega-power station with a 50 foot beam...

SSB for short (300 mile) paths with good signals, CW for weaker signals,
Pick a radio that receives on the same frequency for either mode so you
can have in CW for transmitting while receiving SSB. The FT726 and 726
don't do that well. Some Icom and recent Tentec HF rigs go to LSB for
CW, even on 10 meters which prevents the cross mode operation. I'm quite
happy that my FT-857s allow for mixed mode contacts with no retuning
when changing modes.

I caught some better conditions during the June contest when I tuned up
that yagi at 6' elevation above ground, and I worked well around the
midwest and sporadic E out to Connecticut.

While more than a 3 element is very desirable, 2 or 4 5 element begins
to be respectable and ANY antenna up and used is better than waiting for
the better antenna to come along.

> 
> Cathy
> N5WVR
> 

73, Jerry, K0CQ