[NLRS] 222 ???

[Brent Casavant]

On Wed, 14 Sep 2005, Clair J. Robinson wrote:

> I have DEMI 2m, 432 and 1296 transverters with 10 watt (max) interfaces. I
> tried playing around with the alc power reduction scheme, but I found it to be
> much too fussy with my FT-990.

I'll second this.  My DEM 222-28 originally had the 100mW drive
configuration, and I used a TIB to interface it to my IC-706MkIIg.  

I found the ALC setting from the TIB to be extremely sensitive, and
it would even change slightly when I replaced the outer case on the
TIB after adjustment (RF leakage inside the TIB?).  Additionally,
the HF SEND line on the 706 appeared to have just enough current
sinking capacity to drive the TIB, without a lot of headroom, which
sometimes made switching operation a bit flakey.  Finally, it was
far far too easy to forget to hook up a critical line here or there,
particularly considering just how many lines are involved with the
TIB.

So, I ordered the 10W (max) common-IF drive kit for the 222-28, and
added it myself.  This *vastly* simplified the cabling from a minimum
of eight cables (PTT, IF and power to TIB; PTT, TxIF, RxIF, power, and
antenna to transverter) down to four (PTT, IF, power, and antenna to
transverter), and led to far fewer "potential to smoke the transverter"
errors.  I could do even better if I ran PTT over the IF line, though
the number of connections would remain the same.  Plus, in my mind,
the fewer individual pieces of equipment, the fewer points of failure.

In short, I've been *very* happy with this arrangement, particularly
considering that my equipment is used almost exclusively in a field
situation, which makes simple setup and teardown much more valuable.

I can only picture going back to split TX/RX if I had a permanent
installation, and even then I'd continue to use a high-power drive
because the ALC driver was just too flakey for my comfort.

There are a number of other options for the 222-28 that aren't
immediately obvious from looking at their online description.
Ask them to rattle off the available options when placing your order.
If ordering a DEM 222-28 pre-built, make sure to specify the 10W
common-IF drive option up-front rather than adding it on later --
it's worth it to not have to mess around with removing the board from
the enclosure.

I'd also inquire as to whether they'll install a better power connector
(e.g. PowerPoles) as the default RCA connector leaves room for unpleasant
error (i.e. touch a live center conductor to the case, blow a fuse, find
that you don't have any spares on hand, and the contest starts in five
minutes -- not that I've ever done that, mind you ;).  I'm not sure if
they'll do this or not, but it wouldn't hurt to ask.

Brent

-- 
Brent Casavant			Dance like everybody should be watching.
www.angeltread.org
KD5EMB, EN34lv