Hank:
It would interesting to see the difference in output levels to the phones
with the new firmware. It's definitely louder, but I haven't measured how
much.
Ron N6IE
www.N6IE.com
----- Original Message -----
From: "pfizenmayer" <pfizenmayer2@q.com>
To: <tentec@contesting.com>
Sent: Saturday, August 29, 2009 8:08 PM
Subject: Re: [TenTec] Head-Phone volume in Orion2
> The headphone output IC in the OII is a stereo IC LM4811. I measured about
> 2.75 ohms output impedance at the headphone jack before I installed the
> RF
> filter . The RF filter in later OII's and the board that TenTec supplies
> has
> surface mount ferrite loaded inductors and the total series resistance in
> each lead is about 24 ohms.So output Z is about 27 ohms each side.
>
> 14060 MHz 50 uv in to RX Antenna.(essentially S9) Spot Tone 400 hz ,
> Sidetone
> set at 100 (max) . Received signal output level set to comfortable
> headphone
> level.(Approximately half of the audio bar level readout with my phones)
>
> ver 2.037j firmware . I have not measured the latest beta.
>
> OPEN CIRCUIT LEFT MAIN RIGHT MAIN
>
> set for comfortable 55.1 mv 55.5 mv
> level (approx 1/2 bar)
>
> SPOT 101.8 mv 102 mv
>
> CW SIdetone 50.7 mv 51.0 mv
>
> NO signal 3.7 mv 3.7 mv
> residual noise
>
> So from the above with about 27 ohms source impedance , you can deduce
> what
> the level will be with various phones.
>
> I use Sony MDR V6 phones which are about 70 ohm drivers and not very
> sensitive (I cannot remmember the spec right now) and the cw spot tone
> level
> to me is marginal.
>
> With input signal as above S9 , Maximum output level open circuit wide
> open
> 1.2 volts RMS , about 3.5 V pk-pk and no visible clipping of clipping.
> All
> measurements on a FLuke 179 true RMS meter.
>
> I know of seceral guys who have done what was suggested and they just use
> the speaker output with appropriate attenuation. You of course lose the
> ability to listen to the sub rx in one ear and the main rx in the other
> ear
> but you solve a whole lot of other issues.
>
> 73 de Hank K7HP
>
> ----- Original Message -----
> From: "Dr. Gerald N. Johnson" <geraldj@weather.net>
> To: <tentec@contesting.com>
> Sent: Saturday, August 29, 2009 8:57 AM
> Subject: Re: [TenTec] Head-Phone volume in Orion2
>
>
>> On Fri, 2009-08-28 at 18:58 -0500, Stuart Rohre wrote:
>>> Use higher impedance headphones, they are more sensitive.
>>> Stuart
>>> K5KVH
>>
>> Not at all necessarily. The original post said 97DB/milliwatt, which
>> shows high power sensitivity. Higher impedance will just raise the
>> required voltage, though if the driver has a large series resistor, a
>> higher impedance headset might receive more power and be louder. There
>> are too many schematics in the Orion2 set to casually trace out the
>> hardware and see what that output resistance might be.
>>
>> It might be that raising the voltage to the headset would work for a
>> particular headset with a step up transformer. That will work best if
>> the headset connection is driven by a solid state audio amp that has
>> lots of feedback to give it a low output impedance with no headset
>> protecting series resistor.
>>
>> A sure cure is in the firmware. Maybe in some custom settings, which
>> ought to be customizable for the varying voltage sensitivity of
>> different headsets.
>>
>> Another sure cure is adding a series resistor, speaker pot, or L-pad to
>> the room speaker line and dropping its level to match the headphones but
>> requires turning up the master volume control which made drive the
>> speaker amplifier into clipping.
>>
>> 73, Jerry, K0CQ
>>
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>>
>
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