strange ILS indicator problem

[blanche cohen]

here's the configuration:

SL30 talking to a TKM MC60 VOR/GS indicator.

On the SL30, the left-right indicator displays correctly when in cruise
and it detects a VOR.
On the MC60, the left-right displays correctly when in cruise and it
detects a VOR.

On the MC60, the glideslope indicator displays correctly when on approach.
But...on approach, there's no left-right indicator on the MC60.

Bench testing and in-aircraft testing by a Garmin shop shows no
problems with either radio or VOR/GS indicator. But I still don't
have the left-right on the MC60 when on approach.

Anyone got any suggestions?

[Ron Rosenfeld]

On 06 Jul 2007 02:09:09 GMT, (blanche cohen) wrote:

>here's the configuration:
>
>SL30 talking to a TKM MC60 VOR/GS indicator.
>
>On the SL30, the left-right indicator displays correctly when in cruise
>and it detects a VOR.
>On the MC60, the left-right displays correctly when in cruise and it
>detects a VOR.
>
>On the MC60, the glideslope indicator displays correctly when on approach.
>But...on approach, there's no left-right indicator on the MC60.
>
>Bench testing and in-aircraft testing by a Garmin shop shows no
>problems with either radio or VOR/GS indicator. But I still don't
>have the left-right on the MC60 when on approach.
>
>Anyone got any suggestions?

Some problem with the interface/connection/wiring between the two?

Are they designed to work together? Have they ever worked together?
--ron

[Blanche]

Ron Rosenfeld > wrote:
>On 06 Jul 2007 02:09:09 GMT, (blanche cohen) wrote:
>
>>here's the configuration:
>>
>>SL30 talking to a TKM MC60 VOR/GS indicator.
>>
>>On the SL30, the left-right indicator displays correctly when in cruise
>>and it detects a VOR.
>>On the MC60, the left-right displays correctly when in cruise and it
>>detects a VOR.
>>
>>On the MC60, the glideslope indicator displays correctly when on approach.
>>But...on approach, there's no left-right indicator on the MC60.
>>
>>Bench testing and in-aircraft testing by a Garmin shop shows no
>>problems with either radio or VOR/GS indicator. But I still don't
>>have the left-right on the MC60 when on approach.
>>
>>Anyone got any suggestions?
>
>Some problem with the interface/connection/wiring between the two?
>
>Are they designed to work together? Have they ever worked together?

According to TKM (and unofficially, Garmin/Apollo tech) there should
be no problems. Since the GS works, and the L/R works when cruising,
it seems that they do play well together.

I think it's a trip to a different Garmin shop to have them follow/check
the wiring. This one didn't want to do that. In fact, the comment
was "I don't know what else to do. It may just be an intermittent
wiring problem". Which sealed the fate of that shop. They don't
want to deal with "small change" customer (like me) when they have
twins that want 530s, entire entertainment centers, etc.

Fine. My checkbook will go someplace else.

[Ron Natalie]

Looking at the SL30 manual, doesn't seem to be any difference
in the needle signal for the LOC versus VOR. There is a line
that comes high when you are tuned to LOC (it's variously used
to kick autopilots into APR mode or to toggle the GPS / COM
annunciator). You don't have a GPS in there do you?

[Ron Rosenfeld]

On 06 Jul 2007 05:09:39 GMT, Blanche > wrote:

>Ron Rosenfeld > wrote:
>>On 06 Jul 2007 02:09:09 GMT, (blanche cohen) wrote:
>>
>>>here's the configuration:
>>>
>>>SL30 talking to a TKM MC60 VOR/GS indicator.
>>>
>>>On the SL30, the left-right indicator displays correctly when in cruise
>>>and it detects a VOR.
>>>On the MC60, the left-right displays correctly when in cruise and it
>>>detects a VOR.
>>>
>>>On the MC60, the glideslope indicator displays correctly when on approach.
>>>But...on approach, there's no left-right indicator on the MC60.
>>>
>>>Bench testing and in-aircraft testing by a Garmin shop shows no
>>>problems with either radio or VOR/GS indicator. But I still don't
>>>have the left-right on the MC60 when on approach.
>>>
>>>Anyone got any suggestions?
>>
>>Some problem with the interface/connection/wiring between the two?
>>
>>Are they designed to work together? Have they ever worked together?
>
>According to TKM (and unofficially, Garmin/Apollo tech) there should
>be no problems. Since the GS works, and the L/R works when cruising,
>it seems that they do play well together.
>
>I think it's a trip to a different Garmin shop to have them follow/check
>the wiring. This one didn't want to do that. In fact, the comment
>was "I don't know what else to do. It may just be an intermittent
>wiring problem". Which sealed the fate of that shop. They don't
>want to deal with "small change" customer (like me) when they have
>twins that want 530s, entire entertainment centers, etc.
>
>Fine. My checkbook will go someplace else.

Well, since they are designed to work together, and both units do so, then
clearly the problem has to be in how they are hooked up, as I wrote.

Reminds me of another story -- I had an intermittent problem with the CDI
on my HSI. There was a "converter" between my KX155 and my HSI (NSD360).
IT was mounted in a very difficult to get at spot so was, of course, the
last thing checked. PRoblem turned out to be bad solder joints inside the
converter -- in other words, it came that way from the factory.
Unfortunately, by the time we diagnosed this, it was years out of warranty.
But the fix was simple.
--ron

[Ron Natalie]

And I did understand you correctly that the SL30's
internal bar graph CDI does read properly on the
LOC frequency?

[Blanche]

Ron Natalie > wrote:
>And I did understand you correctly that the SL30's
>internal bar graph CDI does read properly on the
>LOC frequency?

Yes. Only the L/R on the VOR indicator is absent. Most of the time
this is a non-issue --- except when on approach, my head needs
to check an additional instrument (the SL30) which is nowhere
near the glideslope indicator.

Another datapoint. Just had a wonderful chat with the Avionics Person
I Trust the Most. She's the
first person (and that includes the Garmin/Apollo people, altho
they may have forgotten to explain it to me) that explained what
could be the problem.

The SL30 has a much narrower horizontal band to receive the localizer.
It's still within FAA requirements, but it's substantially smaller
than what we've been used to for...what...50 years? She says that
Garmin/Apollo knows this, understands this, but since it's legal,
they don't have much motivation to change it. This does not happen
on the 430/530 equipment, BTW.

This is a great explanation, but I still don't understand why I
can see the L/R on the SL30 during approach, but not on the VOR
indicator. Only thing I can think of, in concert with her explantion
is that the SL30 is sending correct info *for the SL30* but the VOR
indicator is "less sensitive" and doesn't display the same level
of granularity. According to the APITTM, going with a different
VOR/GS indicator (e.g. a Garmin) wouldn't resolve the issue.

I dunno. I'm gonna go have more chocolate brownies and chill.