[Amps] 300Hz sidebands

[Conrad PA5Y]

Hello Geert. 

Yes, I did try 3 different drivers, and several amplifiers off this HT supply. The same result. 

K3S>transverter>driver amp> PA
TS2000 
IC746

Same result.

I eventually got the supply out of the rack and took the lid off. The reason for the sidebands was quite obvious, a previous owner had removed the HT choke, I also tested the 8uF cap, it was 7.85uF my DER EE DE 5000 LCR meter. The original choke will be sent to me this week. These sidebands have been there for the 5 years that I have run this amp.

Regards

Conrad PA5Y

-----Original Message-----
From: Amps <amps-bounces at contesting.com> On Behalf Of Geert Jan de Groot
Sent: 24 May 2021 19:53
To: amps at contesting.com
Subject: Re: [Amps] 300Hz sidebands

On 23/05/2021 20:52, amps-request at contesting.com wrote:
> I have several tetrode amplifiers that run from a 3PH 50Hz supply. With the advent of the FT8 I have become aware that I have 300Hz sidebands at only -50dBc, this is obviously unacceptable.

Apologies for asking, but have you tried a different driver transceiver to see if the signal (level and/or frequency) changes?

Geert Jan


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