Antenna problems

Surprisingly it was a non-connection. The coax was not attached to the
antenna at all. It is amazing to me that it recieved any signal at all.

Mike
MU-2
Helio Courier


wrote in message
news:4w8Md.5398$uc.1741@trnddc03...
Mike,

The symptoms you describe suggest an intermittent connection somewhere in
the nav receive RF chain. If the GS and VOR/LOC use the same antenna, and
the GS works OK, this suggests that the problem is most likely in the
splitter or the cabling/connectors between the splitter and the radio.
The
"open" VOR output on the splitter MIGHT be a source of the problem, but
it's
not very likely. (However, terminations are cheap and simple to
install --
I'd put one on just for general principles.)

See if you can duplicate the problem on the ground in an area where a VOR,
VOT, or LOC signal can generally be received. Watch the NAV flag while
wiggling the various cables, connectors, etc. On the other hand, any
avionics shop should have the equipment needed to quickly and accurately
check out the entire antenna/splitter/cabling system.

--
-Elliott Drucker

Some of the coax is RG-58U, would the newer RG 400U improve things?

Like a band-aid would help a broken arm. RG-58 is just fine for 99.999% of
all installations.



The splitter will supply two VOR recievers. Am I losing something even
though I have only one reciever plugged in? Would a splitter with only
one GS and one VOR output help any? (I doubt it)?

Depends on the splitter. Put a connector with a 47 ohm resistor on the
unterminated arm and see if things improve.



I haven't been up on a ladder to look at the antenna but is the problem
likely to be grounding and/or corrosion? I also have not followed the
coax all the way from the antenna to the radio so there could be
connectors along the way, how much do you lose for each connector?

Corrosion probable. Each connector pair is less than a tenth of a dB, and
not a factor.

Jim

And I wouldn't have you for a customer for all the tea in China. What a
numbnuts.

Jim




"kage" wrote in message
...

After spending at least $9000 for a 530 and then installation, I can't
imagine not ripping out all the crappy old antenna and wiring and replace
with new. How old IS that junk?

I wouldn't even use a technician who didn't automatically do that.

Believe me,

You are the LAST person I'd let near my plane. Know it all loose cannon!

Karl


"RST Engineering" wrote in message
...
And I wouldn't have you for a customer for all the tea in China. What a
numbnuts.

Jim




"kage" wrote in message
...

After spending at least $9000 for a 530 and then installation, I can't
imagine not ripping out all the crappy old antenna and wiring and replace
with new. How old IS that junk?

I wouldn't even use a technician who didn't automatically do that.

"Mike Rapoport" wrote in message
ink.net...
Surprisingly it was a non-connection. The coax was not attached to the
antenna at all. It is amazing to me that it recieved any signal at all.

Mike
MU-2
Helio Courier


In the TV biz, we call that an "Air Gap."

Glad your trouble turned out to be something reasonable.

Jay Beckman
PP-ASEL
Chandler, AZ

Just for future reference... it's supposed to be "open".

The shields of the coax tie to the two blades of the antenna.

The center cable goes through and is open at the far end.

It's a 1/4 wave transformer... open at the far end reflects
as shorted at the end by the antenna. Put away your
E6Bs and take out your Smith Charts!

The phase reversal causes the thing to act as if it's balanced.
The length of the open end section is critical.

Bill Hale

wrote:
: It's a 1/4 wave transformer... open at the far end reflects
: as shorted at the end by the antenna. Put away your
: E6Bs and take out your Smith Charts!

Most EE departments don't teach Smith charts anymore. "Not necessary since a
computer can calculate the wave equation more accurately anyway."

*Sigh*

-Cory

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************