[hpsdr] [Q] no RFI power supply for HPSDR?

[Tom Holmes, N8ZM]

Hi Ken...

The TAPR supply takes 12V DC in, and makes the other voltages from that.
Except for the -12V output, all of the other voltages are derived from
linear regulators, so are very quiet.

The -12 V is generally not needed, and there is a jumper available to
disable it, so that noise can also be eliminated. If you do find that you
need it, a few worry beads on the -12V and return should be adequate. The
only challenge is that the LPU plugs directly into the Atlas, so it won't be
easy to add the beads. The good news, though, is that I have not heard any
complaints so far about noise from that part of the LPU.

Hi Ron!

Regards,

Tom Holmes, N8ZM
Tipp City, OH
EM79xx

-----Original Message-----
From: hpsdr-bounces at lists.openhpsdr.org
[mailto:hpsdr-bounces at lists.openhpsdr.org] On Behalf Of Ronald Cox
Sent: Monday, April 19, 2010 11:27 AM
To: Ken N9VV
Cc: OpenHPSDR
Subject: Re: [hpsdr] [Q] no RFI power supply for HPSDR?

***** High Performance Software Defined Radio Discussion List *****

Ken,
It is common practice now on embedded systems to use RF filters on every I/O
pin of a controller such as an engine controller. With over 30 years of
experience as a system engineer on GM powertrain controllers, other on-board
computers, and race car controllers for CART and Indy cars, the only way to
win the RFI (both radiated out and incoming) battle is to be 100% thorough
in the application of RFI suppression.

Ron W9KFB
Indianapolis


On Apr 19, 2010, at 11:07 AM, Ken N9VV wrote:

> ah ha! thanks Ron. O.K. I put a single big choke on the output of my
Astron last night and it lowered the RFI to -110db. But there
> is something wrong with the Astron and I want to replace it. I
> wonder about the TAPR power supply for the HPSDR?
> 
> many thanks for your good advice,
> Ken
> 
> 
> On 4/19/2010 9:58 AM, Ronald Cox wrote:
>> Ken,
>> I have found that you can use most computer power supplies (my experience
is mostly with Antec supplies) if you are methodical in the application of
clamp on RFI suppression on every wire bundle leaving the power supply. You
can't just put a couple on the harness and check to see if the RFI is
effected. It is all or nothing! I typically test a rig after I assemble it
and see what the spikes look like before the treatment, then I put in 10 to
15 of the clamp on TDK chokes that I buy on eBay from Hong Kong for 88 cents
each. Then I check out the completed unit and it is like magic, all the
unwanted signals are gone...
>> 
>> Ron W9KFB
>> Indianapolis
>> On Apr 19, 2010, at 10:42 AM, Ken N9VV wrote:
>> 
>>> ***** High Performance Software Defined Radio Discussion List *****
>>> 
>>> Hi, has anyone seen a review of computer style
>>> power supplies that have NO RFI generated from
>>> them? I am looking for a small power supply for
>>> my 3 board (Mercury + Ozy + Penelope) HPSDR gear.
>>> 
>>> thank you for reading my email,
>>> 73 Ken N9VV
>>> _______________________________________________
>>> HPSDR Discussion List
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>> 
>> 
> 
> -- 
> if it's not CW it's CB

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