Radio Squeal

[B. Jensen]

I just hard wired my ANR headset into my ship's power so that I no
longer have to use a 9v battery as a power source. Now I am getting an
intermittent squeal when I transmit. I never had this problem with the
9v power pack. My ANR is a Headsets Inc. conversion to a David Clark
headset.

Any ideas how to solve this problem. I used the Headset's Inc. power
cord for the installation.

Thanks,

BJ

[Bob Martin]

> I just hard wired my ANR headset into my ship's power so that I no
> longer have to use a 9v battery as a power source. Now I am getting an
> intermittent squeal when I transmit. I never had this problem with the
> 9v power pack. My ANR is a Headsets Inc. conversion to a David Clark
> headset.
>
> Any ideas how to solve this problem. I used the Headset's Inc. power
> cord for the installation.
>
> Thanks,
>
> BJ

Don't know if this is related, but we get a soft whine over the intercom
once the alternator kicks in on our RV-6 (it usually won't start charging
till you run the engine up), and the strobes cause a bit of interference
too. Ours are on a battery pack in line with the cord.

[EDR]

In article >, B. Jensen
> wrote:

> I just hard wired my ANR headset into my ship's power so that I no
> longer have to use a 9v battery as a power source. Now I am getting an
> intermittent squeal when I transmit. I never had this problem with the
> 9v power pack. My ANR is a Headsets Inc. conversion to a David Clark
> headset.
> Any ideas how to solve this problem. I used the Headset's Inc. power
> cord for the installation.

Is there a built-in intercom?

Is there a portable intercom?

[mikem]

Need more info:

Engine running or not?

Type of aircraft, metal, wood, fabric?

Where is the COM antenna relative to the radio, headphone jack,
intercom, audio panel?

Is the squeal like rf feedback, or is it more like alternator whine?

MikeM



On Fri, 17 Oct 2003 02:52:30 -0500, "B. Jensen"
> wrote:

>I just hard wired my ANR headset into my ship's power so that I no
>longer have to use a 9v battery as a power source. Now I am getting an
>intermittent squeal when I transmit. I never had this problem with the
>9v power pack. My ANR is a Headsets Inc. conversion to a David Clark
>headset.
>
>Any ideas how to solve this problem. I used the Headset's Inc. power
>cord for the installation.
>
>Thanks,
>
>BJ

[Jules]

overhead speaker on?

B. Jensen wrote:

> I just hard wired my ANR headset into my ship's power so that I no
> longer have to use a 9v battery as a power source. Now I am getting an
> intermittent squeal when I transmit. I never had this problem with the
> 9v power pack. My ANR is a Headsets Inc. conversion to a David Clark
> headset.
>
> Any ideas how to solve this problem. I used the Headset's Inc. power
> cord for the installation.
>
> Thanks,
>
> BJ
>

[[email protected]]

There is a very good chance that the RF from your transmitter is
getting into the Head Sets Inc power supply since they lack the
necessary bypass caps on the input and output and is causing the
squeal that you hear.

The power supply they sell leaves a lot to be desired. They did not
install any bypass caps on the internal three terminal regulators and
they tend to oscillate due to the aircraft wiring inductance and lack
of sufficient loop margin. The caps are shown on the regulator data
sheets and are needed to insure sufficient loop gain and phase margin.
The internal DC to DC switching converter also puts out loads of
unstable harmonics that is easily visible on a spectrum analyzer. If
you look at the wave forms on a scope you will see several cycles of
ringing each time the converter switches. This indicates very poor
gain & phase margin on the three terminal regulators. I added 4
small caps and now it no longer spoils reception of my Loran and ADF.


Whoever designed the Head Sets Inc power supply needs to be sent back
to Electronics 001 class.

John

On Fri, 17 Oct 2003 02:52:30 -0500, "B. Jensen"
> wrote:

>I just hard wired my ANR headset into my ship's power so that I no
>longer have to use a 9v battery as a power source. Now I am getting an
>intermittent squeal when I transmit. I never had this problem with the
>9v power pack. My ANR is a Headsets Inc. conversion to a David Clark
>headset.
>
>Any ideas how to solve this problem. I used the Headset's Inc. power
>cord for the installation.
>
>Thanks,
>
>BJ

[B. Jensen]

EDR wrote:

>In article >, B. Jensen
> wrote:
>
>
>
>>I just hard wired my ANR headset into my ship's power so that I no
>>longer have to use a 9v battery as a power source. Now I am getting an
>>intermittent squeal when I transmit. I never had this problem with the
>>9v power pack. My ANR is a Headsets Inc. conversion to a David Clark
>>headset.
>>Any ideas how to solve this problem. I used the Headset's Inc. power
>>cord for the installation.
>>
>>
>
>Is there a built-in intercom?
>
>Is there a portable intercom?
>

No, it has no intercom at all. Only a simple Comm radio and transponder
with mode C.

BJ

[B. Jensen]

Nope, it the radio has no overhead speaker. Only a plug for a headset.

BJ

Jules wrote:

> overhead speaker on?
>
> B. Jensen wrote:
>
>> I just hard wired my ANR headset into my ship's power so that I no
>> longer have to use a 9v battery as a power source. Now I am getting
>> an intermittent squeal when I transmit. I never had this problem with
>> the 9v power pack. My ANR is a Headsets Inc. conversion to a David
>> Clark headset.
>>
>> Any ideas how to solve this problem. I used the Headset's Inc. power
>> cord for the installation.
>>
>> Thanks,
>>
>> BJ
>>
>

[B. Jensen]

John,

Thanks for the reply. I'm not a very astute electrical guy, so please
explain to me what "caps" are and how I can modify the power cord to my
Headsets Inc. ANR to eliminate this problem.

Many thanks,

BJ

wrote:

>There is a very good chance that the RF from your transmitter is
>getting into the Head Sets Inc power supply since they lack the
>necessary bypass caps on the input and output and is causing the
>squeal that you hear.
>
>The power supply they sell leaves a lot to be desired. They did not
>install any bypass caps on the internal three terminal regulators and
>they tend to oscillate due to the aircraft wiring inductance and lack
>of sufficient loop margin. The caps are shown on the regulator data
>sheets and are needed to insure sufficient loop gain and phase margin.
>The internal DC to DC switching converter also puts out loads of
>unstable harmonics that is easily visible on a spectrum analyzer. If
>you look at the wave forms on a scope you will see several cycles of
>ringing each time the converter switches. This indicates very poor
>gain & phase margin on the three terminal regulators. I added 4
>small caps and now it no longer spoils reception of my Loran and ADF.
>
>
>Whoever designed the Head Sets Inc power supply needs to be sent back
>to Electronics 001 class.
>
>John
>
>On Fri, 17 Oct 2003 02:52:30 -0500, "B. Jensen"
> wrote:
>
>
>
>>I just hard wired my ANR headset into my ship's power so that I no
>>longer have to use a 9v battery as a power source. Now I am getting an
>>intermittent squeal when I transmit. I never had this problem with the
>>9v power pack. My ANR is a Headsets Inc. conversion to a David Clark
>>headset.
>>
>>Any ideas how to solve this problem. I used the Headset's Inc. power
>>cord for the installation.
>>
>>Thanks,
>>
>>BJ
>>
>>
>
>
>

[[email protected]]

Caps are short for "Capacitors". I have been looking for where I
reverse engineered and drew the schematic for the Head Sets inc power
supply but I have not been able to find it. I may have tossed it so I
will have to go from memory of about two years ago when I fixed mine.
It is installed in the aircraft so I can not look at it. I think
that they use two LM340 three terminal regulators and a TI low cost DC
to DC converter. You can down load the data sheets at:
http://www.national.com/pf/LM/LM340.html#Datasheet

Add the capacitors recommended by the data sheet and parallel with a
0.1uf ceramic cap for RF bypassing. Get someone that knows how to
solder electronics to do this for you.

Maybe Head sets Inc has gotten wise and fixed the design but they were
still clueless at Oshkosh.

John

On Sun, 19 Oct 2003 18:54:05 -0500, "B. Jensen"
> wrote:

>John,
>
>Thanks for the reply. I'm not a very astute electrical guy, so please
>explain to me what "caps" are and how I can modify the power cord to my
>Headsets Inc. ANR to eliminate this problem.
>
>Many thanks,
>
>BJ
>
wrote:
>
>>There is a very good chance that the RF from your transmitter is
>>getting into the Head Sets Inc power supply since they lack the
>>necessary bypass caps on the input and output and is causing the
>>squeal that you hear.
>>
>>The power supply they sell leaves a lot to be desired. They did not
>>install any bypass caps on the internal three terminal regulators and
>>they tend to oscillate due to the aircraft wiring inductance and lack
>>of sufficient loop margin. The caps are shown on the regulator data
>>sheets and are needed to insure sufficient loop gain and phase margin.
>>The internal DC to DC switching converter also puts out loads of
>>unstable harmonics that is easily visible on a spectrum analyzer. If
>>you look at the wave forms on a scope you will see several cycles of
>>ringing each time the converter switches. This indicates very poor
>>gain & phase margin on the three terminal regulators. I added 4
>>small caps and now it no longer spoils reception of my Loran and ADF.
>>
>>
>>Whoever designed the Head Sets Inc power supply needs to be sent back
>>to Electronics 001 class.
>>
>>John
>>
>>On Fri, 17 Oct 2003 02:52:30 -0500, "B. Jensen"
> wrote:
>>
>>
>>
>>>I just hard wired my ANR headset into my ship's power so that I no
>>>longer have to use a 9v battery as a power source. Now I am getting an
>>>intermittent squeal when I transmit. I never had this problem with the
>>>9v power pack. My ANR is a Headsets Inc. conversion to a David Clark
>>>headset.
>>>
>>>Any ideas how to solve this problem. I used the Headset's Inc. power
>>>cord for the installation.
>>>
>>>Thanks,
>>>
>>>BJ
>>>
>>>
>>
>>
>>

[EDR]

In article >, >
wrote:

> Maybe Head sets Inc has gotten wise and fixed the design but they were
> still clueless at Oshkosh.

If HSI has fixed the design, call them and tell them you need the new
power supply because yours is broken. That seems to be the simplest
solution. Why should you do all the work? You already paid for the mod.

[B. Jensen]

EDR wrote:

>In article >, >
>wrote:
>
>
>
>>Maybe Head sets Inc has gotten wise and fixed the design but they were
>>still clueless at Oshkosh.
>>
>>
>
>If HSI has fixed the design, call them and tell them you need the new
>power supply because yours is broken. That seems to be the simplest
>solution. Why should you do all the work? You already paid for the mod.
>

I talked to a tech person at HSI today. They are making me an upgraded
power cord to install in my A/C. It appears they have discovered their
old one has some faults and have designed a new one.

BJ