On 9/30/2011 5:56 PM, Tõnno Vähk wrote:
> 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.
The Bose are one of the most comfortable headsets and light weight
headsets you can find and they have an advantage most headsets hams use
do not. They are noise canceling and virtually take you out of the noisy
world of multi op. They also have a *directional noise canceling*
mike. If you haven't used ANRs you have really missed something. the
Bose name does bring a premium in cost.
Unfortunately you will find they use an electret mike and are not
compatible with rigs using dynamic mikes. You would have to
independently power the mike.
it can be done, but...
Aviation headsets with Active Noise Canceling along with the
directional, noise canceling mikes are a joy to use in noisy locations
and even though they are expensive are worth it! I've never understood
why they aren't the norm for contest, multi-op stations or for Field
Day. You do not hear a sound from stations ops just a few feet either
side of you, nor does the mike pick up those sounds. The mike response
is also designed for communications, not high fidelity.
In an airplane (prop driven) you don't hear the normal engine or prop
sounds, but you do hear the wind and engine accessories which you
normally never hear.
IF I could find a good set that would work well with the 5000MP I
certainly would purchase a them. They aren't for every one, but there's
no replacement for multi op in noisy locations.
BTW early ANRs were heavy and *hot* in the summer. On a 5 hour flight
(1000 miles) I'd fold up a washcloth to put under the head band as it'd
leave groves in the skin on the top of my head. After a few hours they
were painful to wear, but later models were a joy compared to them.
73
Roger (K8RI)
>
> 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.
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