Tony,

An ADF is basically an AM radio receiver with some added circuitry that
uses a special antenna that allows us to derive the direction of the
signal. Many of these units use discrete (individual) electronic
components, AND most of these units are quite old. Certain capacitors in
these units shift their electronic values over time, causing changes in
the circuitry's operation. Hence, they need to be realigned every now
and then. If not, over time the value shift in some components may make
the unit not tune a signal or will not point to the station at all.

The difficulty is in finding a radio shop that has the tools and
personnel to align your ADF. This is usually done in the airplane
because the 2 antennas (loop and sense) need to be aligned and "trimmed"
with the unit. So, you need to bring the airplane to the shop for best
results. Depending on where you are located, this may not be easy. Take
a look in Trade-a-Plane or other publications to see if there is a shop
near you.

As an alternate, you can ship the unit out. That may or may not solve
the problem depending on the antennas in your plane. If they happen to
be close to the values of the test antennas at the shop, it will work.
If not, the unit may may not work at its peak performance.

Maybe some radio repair person can comment on the criticality of the
antenna adjustment. I do not have a whole lot of experience with radios.

Good Luck,
Mike

tony roberts wrote:
Hi
Today I was flying north and my ADF was tuned to an NDB.
The needle pointed at 330 degrees (or 11 O'clock) until I reached the
NDB, and then it swung until it pointed behind.
I dialed up the next NDB and it pointed at 330 again until passage.
And I dialed up another NDB - same indication - all of them wrong.
On the return trip - same indications.
It seems logical that the nav, ADF head and antenna are working because
I get a reading on station passage, but other than that, if I am tuned
to an NDB anywhere ahead of the aircraft the needle points at 11
O'clock.
Any ideas?

Thanks

Tony


__________________________________________________ _____________________________
Posted Via Uncensored-News.Com - Accounts Starting At $6.95 - http://www.uncensored-news.com
The Worlds Uncensored News Source