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 Post subject: Polyakov mixer working for DSB generation?
PostPosted: Jul Mon 26, 2021 9:47 am 
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Joined: Jun Wed 19, 2019 11:07 am
Posts: 68
Hi, I have used this Polyakov mixer and works ok on receive. However I am trying to generate DSB and I can sense no RF out of the mixer when feeding the audio signal at the low end or directly at the LOSC port. Can't this mixer be used that way to generate DSB?


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 Post subject: Re: Polyakov mixer working for DSB generation?
PostPosted: Jul Tue 27, 2021 5:56 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 10934
Location: Santa Rosa, CA
Might be a better post in Home Brew section??

Rich


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 Post subject: Re: Polyakov mixer working for DSB generation?
PostPosted: Jul Thu 29, 2021 10:16 am 
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Joined: Mar Thu 01, 2018 1:30 am
Posts: 733
sv3ora wrote:
Hi, I have used this Polyakov mixer and works ok on receive. However I am trying to generate DSB and I can sense no RF out of the mixer when feeding the audio signal at the low end or directly at the LOSC port. Can't this mixer be used that way to generate DSB?


Increase oscillator drive. See if it works. It won't. Try a balanced version with self biasing and a transformer.


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 Post subject: Re: Polyakov mixer working for DSB generation?
PostPosted: Jul Thu 29, 2021 3:46 pm 
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Joined: Mar Thu 01, 2018 1:30 am
Posts: 733
Self biasing with R1, C4, C5. Now the oscillator drive need not be adjusted all the time plus it's single balanced.


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 Post subject: Re: Polyakov mixer working for DSB generation?
PostPosted: Jul Thu 29, 2021 3:53 pm 
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Joined: Mar Thu 01, 2018 1:30 am
Posts: 733
Double balanced version. It will generate DSB.


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Last edited by Dare4444 on Jul Thu 29, 2021 4:07 pm, edited 1 time in total.
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 Post subject: Re: Polyakov mixer working for DSB generation?
PostPosted: Jul Thu 29, 2021 4:04 pm 
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Joined: Mar Thu 01, 2018 1:30 am
Posts: 733
You'll need opamps to combine the audio during Rx and generate 0 and 180 degree phase shift AF to drive the mixer during TX. This circuit should have excellent AM rejection and carrier suppression thanks to the transformer. Match the diodes.


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 Post subject: Re: Polyakov mixer working for DSB generation?
PostPosted: Jul Fri 30, 2021 5:49 am 
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Joined: Dec Sat 28, 2019 4:18 pm
Posts: 1086
Location: Corinth, TX
I don't think back-to-back diodes will work.

This article discusses microwave mixers, but the BASIC configurations still apply:
https://eng.libretexts.org/Bookshelves/ ... les_(Steer)/06%3A_Mixer_and_Source_Modules/6.03%3A_Single-Ended_Balanced_and_Double_Balanced_Mixers#:~:text=6.3.5%20Summary%20%20%20%20Mixer%20Type%20,m%20...%20%20%20Increasingly%20complex%20circuitry.%20

John


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