On Tue, 25 Jan 2011 07:03:36 +0000 (UTC), Meat Plow
wrote:

On Mon, 24 Jan 2011 22:46:57 -0800, Jeff Liebermann wrote:

However, the real question what frequency are you hearing? My guess(tm)
is very little fundamental (167.9) and plenty of harmonics.

Depends if the PL tone is dirty?

Yes. If the high pass filter is doing its job, then you a pure sine
wave (i.e. no harmonics) will NOT be heard in the speaker, even if it
is slightly over deviated. The catch is that the de-emphasis network
makes low frequency modulation rather loud while attenuating the highs
with a -6dB/octave roll-off. If the PL deviation is high enough, it
will hit some limit, clip, and therefore generate harmonics. Each
radio has it's own limit as to how much PL over-deviation it can
handle. My guess is anything up to about +/- 1.5KHz is fairly clean.

It may be or at too high a level?

No. See previous guesswork. If the over-deviated, but clean, you
should not be able to hear it through the high pass filter (unless the
tone is sufficiently close to the filter edge to leak through. If you
have a service monitor, you should be able to test the VX-5R receiver
for how much PL it can handle before it clips and spews harmonics.

Yet
you can't even hear it on the FT-60.

Different tolerances to over deviated PL? I don't know without
running some bench tests on the radios.

Yeah its detectable on a couple different scanners. And even on the
internet scanners used by scanner-911-something.com Lets you listen to
police on your computer or Ipod Touch.

Most scanners have really marginal PL high pass filters. Internet
scanners are a different horror story. Some spew flat audio directly
from the discriminator. The result is that this bypasses the
de-emphasis network and high pass PL filter. RadioReference.com has
recognized the problem and inserts de-emphasis and high pass filters
on their end, but that's a band-aid. The filtering really should be
done at the source. Sometimes they forget, and the audio really
sounds awful and full of PL buzz. Other reflectors just resend what
they receive, resulting in the same awful audio and buzz. No clue
what you're hearing. I would put the feed on an audio spectrum
analyzer and look at what's being received. If the audio envelope
looks like it's sloping downward at about -6dB/octave, you're getting
flat audio. If the PL looks like a comb line, it's being clipped
somewhere.

Yeah. If I crank the volume the howl goes away faster.

Huh? That's backwards if it's microphonics. I like mysteries but this
is more than a little odd.

It kid ov validates the grounding problem I first read. More vibrates
seats the grounds. I will first try to dispute or prove this by following
the instructions I have archived. Before I try pressure on the board.

Sounds fair. Radio diagnostics and service by remote control is far
from perfected. I'm always open to alternative explanations.

Both Ft-60 packs are factory. And both charge normal on the rapid
charger. It stumps me why only one charges using the cig plug.

Bad connection on the battery monitor contact? Sorry, but I can't
think of anything better.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558