[AMRadio] Ranger Modulation


Larry Taft ltaft at charter.net
Thu Nov 16 00:10:36 EST 2006


What happens when you hook the sig gen to the mic input, skipping the 
D104?  While you're at it do a frequency response curve of the setup.  
Oft times this is an interesting test.
Larry K2LT

A.R.S. - W5AMI wrote:
> You might also try reversing the leads soldered to the cartridge.
>
>
> On 11/15/06, Larry Taft <ltaft at charter.net> wrote:
>> Try reversing the phase of the audio by swapping the output leads of the
>> modulation xfmr.
>> Asymmetrical modulation?  And too much in the negative direction is the
>> flat line.
>> Weak tube in the audio chain causing lack of gain needed for the
>> positive peak.
>> I understand what I'm trying to say.  I reserve my right to say it 
>> wrong!
>>
>> Larry  K2LT
>>
>> Jack Schmidling wrote:
>> > I suspect my mic problem is with the cartridge and I will be getting a
>> > new one.
>> >
>> > The now problem seems to be that I just can not seem to get 100%
>> > modulation no matter what mic I use.
>> >
>> > When I adjust the scope so the carrier is +/- 1 div, I can never get
>> > it quite to +/- 2 and 1.5 is pretty typical.
>> >
>> > On the other hand, I have no trouble getting a flat line between
>> > cycles with too much audio which I understand is the indication for
>> > over modulation.
>> >
>> > I am using a audio generator at 1 kHz talking to an earphone, against
>> > the mic.  The modulation meter can easily be pinned if I use an
>> > amplified mic but it has no effect on the top of the envelop.
>> >
>> > What does all this mean?
>> >
>> > js
>> >
>>
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>
>




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