[ARC5] Lopsided modulation

[Tim]

Hi Neil - Are you using a very "high Q" antenna system somehow?  Tuned to
your carrier or what is your stronger sideband - thus attenuating the
"wimpy" sideband?  I dunno, just a guess...
Glad to hear you have them on the air!

Tim
N6CC

On Sat, Feb 24, 2018 at 2:07 PM, AKLDGUY . <neilb0627 at gmail.com> wrote:

> FM does not seem to be present in either his signal or mine. The carriers
> are straight lines on the waterfall display. Actually, there is one
> operator on the net whose carrier is a fuzzy line when he speaks, but his
> sidebands are symmetrical. I'm stumped.
>
> Neil ZL1ANM
>
> On 25/02/2018 10:30 AM, "Richard Knoppow" <1oldlens1 at ix.netcom.com> wrote:
>
>>     That affects the upward vs downward modulation but not the strength
>> of the sidebands. A frequent cause of asymetrical sidebands is incidental
>> FM. If the oscillator is being affected by the modulation it can be the
>> cause.
>>     The scope display will not show assymetry of the upper vs lower
>> sidebands although it will certainly show assymetry of upward vs downward
>> modulation.
>>
>> On 2/24/2018 1:18 PM, Jim Wiley wrote:
>>
>>> One reason could be that your voice in itself is non-symmetrical.  If
>>> you can do so easily, try reversing the "polarity" if the modulation
>>> transformer, and see if that helps.  If it does, your can leave it set the
>>> way that works best for you. Monitoring the modulation envelope with an
>>> oscilloscope is always  the best way.
>>>
>>> - Jim, KL7CC
>>>
>>>
>>>
>>> On 2/24/2018 11:38 AM, AKLDGUY . wrote:
>>>
>>>> A friend and I are running Command transmitters on the local 75 meter
>>>> AM net, with full plate and screen modulation. We monitor our transmissions
>>>> on the local SDR receiver site which has a waterfall display. In both
>>>> cases, the lower sideband shows as considerably stronger than the upper,
>>>> and this has us perplexed. Our stations are the only ones affected.
>>>>
>>>> I have never seen anything in the literature to explain this. Downward
>>>> modulation is a problem with AM, but articles do not indicate whether
>>>> lopsided modulation results.
>>>>
>>>> My transmitter is the AN/ARC-5, absolutely unmodified and running 40W
>>>> input due to dynamotor constraint. His is the SCR-274 modified for plate &
>>>> screen modulation and running twice that.
>>>>
>>>> Anyone suggest a reason for the unequal sidebands?
>>>>
>>>> Neil ZL1ANM
>>>>
>>>
>>
>> --
>> Richard Knoppow
>> 1oldlens1 at ix.netcom.com
>> WB6KBL
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>
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