Testing for power supply "hash"
 

I want to see if my new switching supply creates "hash" on any band.

Is it enough to hook up to a dummy load and listen to the difference
between battery power and the power supply in the middle of every band
of interest? Should I disable any controls or automatic adjustments?

What does hash sound like? I have been fortunate not to have
experienced it (to my knowledge).

Ken KC2JDY


Ken
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Ken,

You'd be better off using an antenna just to check for radiated noise as well
as conducted noise. You'll have to tune across each band because the hash
might be frequency specific and/or broad band. Depending on a lot of factors,
it can sound like a buzz, hum, variations due to load, etc. but if it's there,
it will be easily recognizable as a "non-signal".

73s,

Evan

Ken,

You'd be better off using an antenna just to check for radiated noise as well
as conducted noise. You'll have to tune across each band because the hash
might be frequency specific and/or broad band. Depending on a lot of factors,
it can sound like a buzz, hum, variations due to load, etc. but if it's there,
it will be easily recognizable as a "non-signal".

73s,

Evan

On Sat, 17 Apr 2004 07:17:08 GMT, Ken wrote:

I want to see if my new switching supply creates "hash" on any band.

Is it enough to hook up to a dummy load and listen to the difference
between battery power and the power supply in the middle of every band
of interest? Should I disable any controls or automatic adjustments?

What does hash sound like? I have been fortunate not to have
experienced it (to my knowledge).

Ken KC2JDY


Ken
(to reply via email
remove "zz" from address)

You might check the qst review of switching power supplies that
appeared 4 or 5 years ago. They tested for "hash." They found "hash"
was far less a problem when a transceiver was in the receive mode,
pulling few amps, versus the transmit mode, when hash was much more
serious, but a moot point, since the receive apparatus is muted.

Bob
k5qwg

On Sat, 17 Apr 2004 07:17:08 GMT, Ken wrote:

I want to see if my new switching supply creates "hash" on any band.

Is it enough to hook up to a dummy load and listen to the difference
between battery power and the power supply in the middle of every band
of interest? Should I disable any controls or automatic adjustments?

What does hash sound like? I have been fortunate not to have
experienced it (to my knowledge).

Ken KC2JDY


Ken
(to reply via email
remove "zz" from address)

You might check the qst review of switching power supplies that
appeared 4 or 5 years ago. They tested for "hash." They found "hash"
was far less a problem when a transceiver was in the receive mode,
pulling few amps, versus the transmit mode, when hash was much more
serious, but a moot point, since the receive apparatus is muted.

Bob
k5qwg

I use a Spectrum Analyzer and a few turns of wire at the end of some
coax to sniff the input/output cables and meter openings. Lacking that,
a portable SW receiver can be used to see if the noise floor increases
as you place the antenna near the power supply. I found the Astron
SS-30M does not radiate any detectable interference, while other
industrial switchers completely can trash out the HF band.
Mike


Ken wrote:
I want to see if my new switching supply creates "hash" on any band.

Is it enough to hook up to a dummy load and listen to the difference
between battery power and the power supply in the middle of every band
of interest? Should I disable any controls or automatic adjustments?

What does hash sound like? I have been fortunate not to have
experienced it (to my knowledge).

Ken KC2JDY


Ken
(to reply via email
remove "zz" from address)

I use a Spectrum Analyzer and a few turns of wire at the end of some
coax to sniff the input/output cables and meter openings. Lacking that,
a portable SW receiver can be used to see if the noise floor increases
as you place the antenna near the power supply. I found the Astron
SS-30M does not radiate any detectable interference, while other
industrial switchers completely can trash out the HF band.
Mike


Ken wrote:
I want to see if my new switching supply creates "hash" on any band.

Is it enough to hook up to a dummy load and listen to the difference
between battery power and the power supply in the middle of every band
of interest? Should I disable any controls or automatic adjustments?

What does hash sound like? I have been fortunate not to have
experienced it (to my knowledge).

Ken KC2JDY


Ken
(to reply via email
remove "zz" from address)

I have an Alinco DM-330MV here and "hash" has not been a problem on any of
the HF bands, nor do I hear any on the BC band. However, the supply does
radiate some weak discrete signals on the 160 meter band, and they are
considerably stronger on the AM Broadcast band. The supply includes a
"noise offset" control, which allows you to alter the frequencies of the
discrete signals and so move them out of the passband where they cause no
problem. I once had an Astron 25 amp switching supply and don't recall
having the problem with the discrete signals on 160 at all with that supply.



"Mike" wrote in message
. com...
I use a Spectrum Analyzer and a few turns of wire at the end of some
coax to sniff the input/output cables and meter openings. Lacking that,
a portable SW receiver can be used to see if the noise floor increases
as you place the antenna near the power supply. I found the Astron
SS-30M does not radiate any detectable interference, while other
industrial switchers completely can trash out the HF band.
Mike


Ken wrote:
I want to see if my new switching supply creates "hash" on any band.

Is it enough to hook up to a dummy load and listen to the difference
between battery power and the power supply in the middle of every band
of interest? Should I disable any controls or automatic adjustments?

What does hash sound like? I have been fortunate not to have
experienced it (to my knowledge).

Ken KC2JDY


Ken
(to reply via email
remove "zz" from address)

I have an Alinco DM-330MV here and "hash" has not been a problem on any of
the HF bands, nor do I hear any on the BC band. However, the supply does
radiate some weak discrete signals on the 160 meter band, and they are
considerably stronger on the AM Broadcast band. The supply includes a
"noise offset" control, which allows you to alter the frequencies of the
discrete signals and so move them out of the passband where they cause no
problem. I once had an Astron 25 amp switching supply and don't recall
having the problem with the discrete signals on 160 at all with that supply.



"Mike" wrote in message
. com...
I use a Spectrum Analyzer and a few turns of wire at the end of some
coax to sniff the input/output cables and meter openings. Lacking that,
a portable SW receiver can be used to see if the noise floor increases
as you place the antenna near the power supply. I found the Astron
SS-30M does not radiate any detectable interference, while other
industrial switchers completely can trash out the HF band.
Mike


Ken wrote:
I want to see if my new switching supply creates "hash" on any band.

Is it enough to hook up to a dummy load and listen to the difference
between battery power and the power supply in the middle of every band
of interest? Should I disable any controls or automatic adjustments?

What does hash sound like? I have been fortunate not to have
experienced it (to my knowledge).

Ken KC2JDY


Ken
(to reply via email
remove "zz" from address)