Antenna problems

You may have water in the coax line. If so it will have a lot of
loss. Find a ham radio operator with a MFJ antenna analyzer and
water will show up as excessive VSWR. This meter has a built in low
power tuneable osc to check the swr so it will not harm any thing.

The flag flipping is most likely due to a beat frequency between the
engine RPM and the glide slope modulation frequency. Change the prop
pitch a little to change the engine speed a hundred RPM and this
should go away. You do not want the prop blades rate to be a sub
multiple of 90 or 150 Hz. This will make the indicator pointers dance
and the flags flip a lot.
John


On Wed, 02 Feb 2005 02:29:34 GMT, "Mike Rapoport"
wrote:

I am having (I think) antenna problems in my Helio Courier. The radio is a
Garmin 530. The antenna is a forward swept :"V" type mounted high on the
vertical stabilizer. There is a splitter that spilts the output from this
one antenna into two VOR signals and a single GS signal. The NAV flag on
the HSI drops into view and then retracts many times on ILS and LOC
frequencies. The GS seems fine and the HSI D-bar doesn't scallop. This
same 530 works fine in the MU-2 and there are no flag issues in the Helio in
GPS mode, so I don't think it is the radio.

A few questions spring to mind:

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

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)?

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?

Mike
MU-2
Helio Courier

Thanks John, I will try to find someone with the antanna analyzer. The GS
doesn't use the NAV flag (the GS pointers just move out of view) so I don't
think that is the problem. I will try changing the RPM anyway.

Mike
MU-2
Helio Courier

"John_F" wrote in message
...
You may have water in the coax line. If so it will have a lot of
loss. Find a ham radio operator with a MFJ antenna analyzer and
water will show up as excessive VSWR. This meter has a built in low
power tuneable osc to check the swr so it will not harm any thing.

The flag flipping is most likely due to a beat frequency between the
engine RPM and the glide slope modulation frequency. Change the prop
pitch a little to change the engine speed a hundred RPM and this
should go away. You do not want the prop blades rate to be a sub
multiple of 90 or 150 Hz. This will make the indicator pointers dance
and the flags flip a lot.
John


On Wed, 02 Feb 2005 02:29:34 GMT, "Mike Rapoport"
wrote:

I am having (I think) antenna problems in my Helio Courier. The radio is
a
Garmin 530. The antenna is a forward swept :"V" type mounted high on the
vertical stabilizer. There is a splitter that spilts the output from this
one antenna into two VOR signals and a single GS signal. The NAV flag on
the HSI drops into view and then retracts many times on ILS and LOC
frequencies. The GS seems fine and the HSI D-bar doesn't scallop. This
same 530 works fine in the MU-2 and there are no flag issues in the Helio
in
GPS mode, so I don't think it is the radio.

A few questions spring to mind:

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

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)?

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?

Mike
MU-2
Helio Courier

Mike
MU-2
Helio Courier


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.

Karl
I practice what I preach.

"kage" wrote in message
...


Mike
MU-2
Helio Courier


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.

Karl
I practice what I preach.


Two years old. Kind of a foolish polity IMHO. The cost of replacing
everything along with the possibility of damaging the interior, cross
threading nutplates, scratching the paint ect outweighs the remote chance
that the coax is bad. Similiarly the antenna is just two pieces of
stainless steel wire and a balun. Now if you had the airplane completely
apart, I would agree that changing any low cost parts that look suspect and
will be difficult to access when the airplane is together makes sense.

Mike
MU-2

The problem turned out to be a broken coax. It was broken at the connector
at the antenna end. The coax was not long enough to reach the antenna
anymore so I theorize that it was broken by someone pulling it tight inside
the fusilage. It also had no strain relief. Seems to be working now (on
the ground)

Mike
MU-2
Helio Courier

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.