Oil on transponder antenna

[Bob]

Is it possible that some oil on the transponder antenna would cause it
to transmit intermittently?

I would have wiped it clean and tried it out but it's 5 OVC today....

Thanx

[rip]

Yes it is. Before I got an air/oil separator that actually worked, my
transponder was very unreliable unless I kept the antenna clean.

Bob wrote:
> Is it possible that some oil on the transponder antenna would cause it
> to transmit intermittently?
>
> I would have wiped it clean and tried it out but it's 5 OVC today....
>
> Thanx

[Tom Jackson]

For what its worth, I also had an intermittant transponder, and finally
concluded that it was due to the coax cable getting damaged by the heat in
the heater duct.

In my Warrior, the coax routes down through the heater ductwork to the belly
of the plane. Every winter, I would experience transponder trouble. I
finally insulated the antenna wire, and now there are no more problems.

"Bob" > wrote in message
...
> Is it possible that some oil on the transponder antenna would cause it
> to transmit intermittently?
>
> I would have wiped it clean and tried it out but it's 5 OVC today....
>
> Thanx

[Bob Chilcoat]

Interesting, I just posted the same question on RAP. See
"Pinging Jim Wier - X-Ponder Antenna Question"

--
Bob (Chief Pilot, White Knuckle Airways)

I don't have to like Bush and Cheney to love America
(Or Kerry, for that matter)

"Bob" > wrote in message
...
> Is it possible that some oil on the transponder antenna would cause it
> to transmit intermittently?
>
> I would have wiped it clean and tried it out but it's 5 OVC today....
>
> Thanx

[MikeM]

Bob wrote:
> Is it possible that some oil on the transponder antenna would cause it
> to transmit intermittently?
>
> I would have wiped it clean and tried it out but it's 5 OVC today....
>
> Thanx

No!

Oil is a pretty good insulator. Oil is used as a coolant in transformers.
It is used to conduct heat away from the non-inductive resistor in a 1Ghz Bird
wattmeter/dummy load that I own.

If your transponder is intermittent, then there is about a 0.1% probability
that wiping the antenna will fix it...


MikeM

[[email protected]]

MikeM > wrote:
> Bob wrote:
> > Is it possible that some oil on the transponder antenna would cause it
> > to transmit intermittently?
> >
> > I would have wiped it clean and tried it out but it's 5 OVC today....
> >
> > Thanx

> No!

> Oil is a pretty good insulator. Oil is used as a coolant in transformers.
> It is used to conduct heat away from the non-inductive resistor in a 1Ghz Bird
> wattmeter/dummy load that I own.

> If your transponder is intermittent, then there is about a 0.1% probability
> that wiping the antenna will fix it...


> MikeM

Clean oil is an insulator.

An oil film with who knows what gunk in it is not such a good insulator.

So, if you change the oil on your antenna regularly...

--
Jim Pennino

Remove -spam-sux to reply.

[mikem]

wrote:


> Clean oil is an insulator.
>
> An oil film with who knows what gunk in it is not such a good insulator.
>
> So, if you change the oil on your antenna regularly...

Nevertheless, I stand by my statement.

In order for dirty oil to effect the transmission, it would have to
carbonize the oil into a conductive track shorting across the insulator
at the base of the monopole. The peak power output from the transponder
is about about 250W, which puts about SQR(250*50)=~110V across the
antenna base.

A little dirty oil will not arc over at 100V!

MikeM

[John]

A film of oil with some dirt attached is still transparent to the RF.


HOWEVER if you wipe the antenna that is attached to a thin skinned
aircraft you will MOVE the antenna slightly. Maybe just enough to
restore connection in the rusty connector joint or the broken solder
joint.
Wiping works just not for the reason stated.
JF

On Mon, 03 May 2004 17:49:46 -0600, mikem > wrote:

>
>
wrote:
>
>
>> Clean oil is an insulator.
>>
>> An oil film with who knows what gunk in it is not such a good insulator.
>>
>> So, if you change the oil on your antenna regularly...
>
>Nevertheless, I stand by my statement.
>
>In order for dirty oil to effect the transmission, it would have to
>carbonize the oil into a conductive track shorting across the insulator
>at the base of the monopole. The peak power output from the transponder
>is about about 250W, which puts about SQR(250*50)=~110V across the
>antenna base.
>
>A little dirty oil will not arc over at 100V!
>
>MikeM

[[email protected]]

mikem > wrote:


> wrote:


> > Clean oil is an insulator.
> >
> > An oil film with who knows what gunk in it is not such a good insulator.
> >
> > So, if you change the oil on your antenna regularly...

> Nevertheless, I stand by my statement.

> In order for dirty oil to effect the transmission, it would have to
> carbonize the oil into a conductive track shorting across the insulator
> at the base of the monopole. The peak power output from the transponder
> is about about 250W, which puts about SQR(250*50)=~110V across the
> antenna base.

> A little dirty oil will not arc over at 100V!

> MikeM

The oil doesn't have to carbonize, nor does it have to arc over to
effect the antenna.

The gunk caught in the oil only has to be lossy at 1 Ghz which most
materials are.

Old melmac dinnerware (the newer stuff seems to be better) would
catch fire in a microwave on occasion because the stuff was so lossy
at microwave frequencies. Melmac is a good insulator at DC.

That would more likely show up as reduced range on the transponder unless
the gunk was lossy enough to start carbonizing the oil, which I doubt
would ever happen unless it got really thick (in which case you need
to look at how you preflight).

As someone else pointed out though, wiping the gunk off is a likely
source of problems if you don't use a gentle touch on those little
rod antennas.


--
Jim Pennino

Remove -spam-sux to reply.

[MikeM]

wrote:

> The oil doesn't have to carbonize, nor does it have to arc over to
> effect the antenna.
>
> The gunk caught in the oil only has to be lossy at 1 Ghz which most
> materials are.

I cant imagine that a little bit of dirty oil could attenuate the
signal by more than a db or two. If your transponder is so anemic
that a db would make a difference, you got more serious problems...


MiKeM

[Nathan Young]

On Sun, 02 May 2004 17:34:05 -0400, Bob > wrote:

>Is it possible that some oil on the transponder antenna would cause it
>to transmit intermittently?
>
>I would have wiped it clean and tried it out but it's 5 OVC today....

Probably not. I suspect a loose signal connection or bad ground
connection in the transponder antenna. When you wipe it clean, you
are probably moving the antenna enough to make a temporary connection.
Hit enough turbulence, and the connection goes bad again.

I'd say this is especially the case if the failure mode is on/off.

-Nathan

[Rob McDonald]

Nathan Young > wrote in
:

> On Sun, 02 May 2004 17:34:05 -0400, Bob > wrote:
>
>>Is it possible that some oil on the transponder antenna would cause it
>>to transmit intermittently?
>> ...
>
> Probably not...

It certainly seems to make a difference on the 172 I fly right now (a
rental). We are out in the boonies so the transponder isn't usually needed,
and the oil accumulates. When people don't clean the antenna before
venturing into civilization controllers comment that they are not getting
our altitude information. I've tried it both ways (unintentionally) and
confirmed this.

Rob

[Orval Fairbairn]

In article >,
Rob McDonald > wrote:

> Nathan Young > wrote in
> :
>
> > On Sun, 02 May 2004 17:34:05 -0400, Bob > wrote:
> >
> >>Is it possible that some oil on the transponder antenna would cause it
> >>to transmit intermittently?
> >> ...
> >
> > Probably not...
>
> It certainly seems to make a difference on the 172 I fly right now (a
> rental). We are out in the boonies so the transponder isn't usually needed,
> and the oil accumulates. When people don't clean the antenna before
> venturing into civilization controllers comment that they are not getting
> our altitude information. I've tried it both ways (unintentionally) and
> confirmed this.
>
> Rob

A friend had the same problem on his 182. I suggested that he switch the
Txp to the DME antenna and vice-versa, as they are identical. He
stopped having Txp problems.