[hpsdr] HUM on piHPSDR SSB TX signal

[Mike Schwendeman]

OOOoops... Formatting error by me, apparently!

My original post on this subject was sent as "Delivery format: PLAIN 
TEXT ONLY.  My second one was sent as the default, AUTO DETECT.  I see 
that this second post was "scrubbed," and when I viewed the scrubbed 
document, it was shown as being simple HTML.  So, I will try again 
(sorry) and this time, I'll use the PLAIN TEXT ONLY mode of delivery format.

My above observations were via the "lists-dot-openhpsdr-dot-org" web 
site.  So, it may well have been presented as text, when delivered by an 
email.

73;  Mike, K0JTA


On 2/19/17 5:13 PM, Mike Schwendeman wrote:
> Hello, again;
>
>     -Just a report on my "hum when I transmit in SSB mode" with the 
> ipHPSDR:  I added a ground to the PI on the negative lead of the power 
> feed to the PI, and the hum is GONE!!!  (I used the negative lead of 
> the Astron power supply as the ground.  -I hope that my assumption 
> that this is actually GROUND!)
>
>     Now, I need to see if I can modify the power bricks that I have on 
> hand, so that the ground can be provided at the negative lead of the 5 
> VDC output from the power supplies.
>
>     It is either that, or I can add a lead that can be clipped to a 
> convenient AC ground.  This seems to be just a bit clumsy... And, I 
> hate to stack another plug onto the power-brick's two 115 VAC prongs.
>
>     If I tie the negative lead to _one of the two 115 VAC prongs_ of a 
> wall-wart supply, the ground reference could be at 115 volts, so I 
> cannot chance this.  (!!)  And with the existing two prong's not 
> having any difference in sizes, I cannot predict which of these two 
> might be the neutral side.
>
>     Ideas???
>
>     Thanks for your support!!!
>
>     73;  Mike, K0JTA