Excellent comments, Oliver. I've not done EME (too many tall trees in
the way), but I do own an XV144, and recently set it up with a vintage
Mirage 2W in to 150W out brick amp of pre-MFJ vintage. Some thoughts
based on my experience.
The internal transverter is rated for about 10W, the external unit for
20W. Both should be carefully cooled and derated for keydown modes,
which is one reasonI sought out that particular Mirage. The other reason
is that minimizing temperature rise in either transverter improves
frequency stability. To minimize heat in the XV144, it should be driven
from the K3 so that 1 mW generates full rated power. Running the
transverter at reduced output also helps. Since I need only 2W drive,
I've set up my XV144 so that 1 mW in yields 10 W out.
For whatever reason, both my XV144, as well as my XV220 that has been on
long term loan to neighbor K6EU, both have some degree of instability,
to the extent that both behave differently with top cover on and off.
One thing I suspect as a cause is poor EMC practice. The antenna
connector is bonded to the chassis, but BNC connectors for interface to
the transceiver are insulated from the chassis. My XVs are fairly old --
I bought them used in 2005 already built, so perhaps current production
is better in this regard. And the XV144 did get a glowing review in QST.
73, Jim K9YC
On Sun,8/31/2014 8:25 AM, Oliver Dröse wrote:
Hi Rich,
don't know the external one (XV144) myself so cannot comment. The
internal one (K144XV) has one drawback: no adequate cooling! Cooling
is done only passively using the left side of the enclosure. As JT65
on EME is a key-down mode you will see that power drops soon and
dramatically, i.e. starting with 10 watts it will drop down to 5-6
watts after 2-3 overs already due to missing heat dissipation. So you
will want to do some external cooling to lessen that effect (but you
will not completely get rid of it from my experience).
Besides this the K144XV is very sensitive, whenever I use mine I
switch off the external pre-amp which is needed for all other
transceivers overhere. :-) And don't forget to order the K144RFLK to
keep the frequency stable.
What you should also consider is which amplifier you want to use. So
the XV144 might be the better solution if you need more drive power.
If you want to think outside the box you can also check other
manufacturers. For serious contesting and EME I'm using the HA1YA
transverter ME2HT-PRO with +30 dBm mixer
(http://www.ha1ya.hu/htmkepek/me2t_protransverterspec.htm) and 60
watts (including adequate cooling) to drive a GS35 amp.
HTH - hope that helps!
73, Olli - DH8BQA
Contest, DX & radio projects: http://www.dh8bqa.de
Am 30.08.2014 14:26, schrieb Richard Thorne:
I'm starting to get the bug to try something different and EME has
grabbed my attention.
I already have a couple K3's and would like to put one to use for
EME. Which is the better option the external 144mhz transverter or
the internal 2m option?
Thanks
Rich - N5ZC
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