[TowerTalk] TowerTalk Digest, Vol 105, Issue 62

[Mahlon Haunschild]

Tonno,

Aviation headsets have microphones that are designed to work with 
aviation-standard mic inputs, which are designed to work with carbon 
microphones.

A while back QST "Hints and Kinks" had an article on adapting aviation 
headsets to ham gear.  Write to me off-list if you can't find it.

regards,

Mahlon - K4OQ

On 9/30/2011 7:41 PM, towertalk-request at contesting.com wrote:
> Subject:
> [TowerTalk] Bose A20 aviation headset for ham purposes?
> From:
> Tõnno Vähk <tonno.vahk at gafm.ee>
> Date:
> Sat, 1 Oct 2011 00:56:56 +0300
>
> To:
> towertalk at contesting.com
>
>
> Hi,
>
> I have been searching for a perfect headset for 48 hour contest operation
> and found Bose A20 aviation headset being highly praised by pilots for
> comfort as well as noise cancelling. Looks like an excellent product.
>
> I wonder if it is usable for ham purposes with my Yaesu radios and
> Microham keyers.
>
> Maybe someone has experience of using aviation headsets?
>
> And I am afraid the impedances of headphones and mic would be a problem?
>
> The A20 manual
> (http://products.bose.com/pdf/customer_service/owners/og_a20_owners_en.pdf
> ) says that:
>
> Microphone (Electret) Bias required: 8 to 16 VDC through 220 to 2200 Ohms.
> Sensitivity: Varies depending on bias and AC radio input impedance.
> Typical output is 600 mV at 114 dB SPL. To assure proper modulation of the
> radio, it is recommended
> that an avionics technician adjusts its input to match the output of the
> microphone.
>
> Microphone (Dynamic) Impedance: 5 Ohms
> Sensitivity: Equivalent to M-87/M-101
>
> The 5 ohm impedance is drastically different from ca 600 ohm level of
> Yaesu and Heil dynamic mics. Would this be usable at all for our
> purposes??
>
> Or maybe the electret mic with modification could be used for Yaesu
> radios?
>
> About headphones the manual says:
>
> Impedance Monaural mode: 160 Ohms ON and OFF
> Stereo mode: 320 Ohms ON and OFF
>
>
> I hope someone who knows more about headphones and mics can help me find
> the answer if this headset can be used.
>
> 73
> Tonno
> ES5TV
>
> p.s. any other recommendations on perfect heatsets (that would not kill
> the ears in 48 hours like Heil) are also very welcome.
>