The power supply ripple will not modulate the amplifier well as it is operating
as a linear amplifier.
If the amp was operating in class C then it would.
73
Gary K4FMX
Gary Schafer
> On Dec 22, 2024, at 5:15 PM, David G4FTC <g4ftc@hotmail.com> wrote:
>
> I've been following this thread with interest.
>
> Could I suggest listening to your own transmitted signal on a local WebSDR?
>
> You can then assess if the ripple is excessive or not.
>
> Regards
>
> David G4FTC
>
> Sent from Outlook for Android<https://aka.ms/AAb9ysg>
> ________________________________
> From: Amps <amps-bounces@contesting.com> on behalf of Michael Tope
> <W4EF@dellroy.com>
> Sent: Sunday, December 22, 2024 5:08:23 PM
> To: amps@contesting.com <amps@contesting.com>
> Subject: Re: [Amps] Acceptable ripple on high voltage plate power supply in
> tetrode amplifiers.
>
> If you were transmitting CW or FT8 and your amplifier was adding hum
> modulation sidebands it would definitely show up on a waterfall of a
> station receiving your signal as copies of the primary signal offset by
> the hum modulation frequency (e.g. 60 Hz, 120 Hz, 180 Hz, etc).
>
> I think you would hear it on a CW signal as well as seeing it on the
> waterfall even with fairly narrow IF filters. For instance, on CW I
> think my K3 normally centers the IF passband at an audio frequency of
> 550 Hz. If I am receiving a CW signal with 60 Hz hum sidebands, I am
> going to hear the primary carrier at an audio frequency 550 Hz, and 60
> Hz hum sidebands at audio frequencies of 490 and 610 Hz. Even if 60 Hz
> is cutoff by the audio filtering of the receiver, it may still be
> perceptible as a beat between the 550 Hz primary tone and the 490 and
> 610 Hz sideband tones. Whatever the case, it is not going to sound like
> a clean tone unless the sidebands are low enough. Offhand, I don't know
> how low it would have to be before it would no longer be noticeable. I
> am sure that has been studied to death.
>
> For an SSB transmitter modulated by a human voice, I don't know if you
> would be able to see hum sidebands on a waterfall plot. With a steady
> audio tone, you would be able to see it, but with human speech there is
> probably too much complexity. Seems like you would be able to hear it,
> however, even with the complexity of human speech (assuming the
> sidebands were big enough) and even if the audio passband didn't extend
> down to the hum frequency. Anyway that's my intuition on this. I am not
> sure it is correct.
>
> 73, Mike W4EF.................
>
>
>> On 12/18/2024 4:16 PM, Lukasz wrote:
>>> On Wed, 18 Dec 2024, 20:01dj7ww@t-online.de,<dj7ww@t-online.de> wrote:
>>>
>>> I use 2µF and no choke with my 3-phase DB6 power supply and nobody hears
>>> any hum.
>>
>> Very interesting.
>>
>> Have you ever measured the ripple? If so, what is it?
>>
>> If you haven't, please give some details of the PSU so I can guesstimate
>> it. What AC/DC voltage and current do you use, is it a normal 3 phase full
>> wave rectifier (50 or 60Hz?) or something else (like a doubler, or half
>> wave etc).
>>
>> Also, have you had a chance to see a waterfall of your SSB signal? I wonder
>> if the correspondents can't hear it has to do with the fact everything
>> under 300Hz is cut off on their end, or there is no hum transmitted? An
>> waterfall would show any 200Hz peak.
>>
>>>
>>> Check with Dr.Alex if you need larger capacitors:
>>> http://www.ur4ll.net/#caps1
>> Thanks, I've got plenty, but no doubt someone else might need it.
>>
>> 73,
>> Łukasz - SP4IT
>>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|