Hum coupling?

[Tom Althoff]

Ten-Tec recommended putting the matching speaker/power supply of my old Omni-V on the RIGHT hand side of the radio.  The audio lines ran on the left side and the transformer in the supply caused hum on receive.

I'm experiencing similar AC hum on the K2 audio.   The K2 sits on top of my Titan II and when the HV is set to operate (kicking in the big HV xfmr directly under the K2) I get the hum.  If I pick the K2 up and move it about 3" away from the Titan then all is well.

Has anyone else experienced hum from nearby power transformers?   I plan on using a 10Amp analog supply (not here yet) and anticipate I might have to keep it away from the K2.   I suspect switching supplies do not cause the same effect.

Tom K2TA
Greenwood Lake, NY
K2 #1117
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft   
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Don Brown-4]

Hi

The K2 is susceptible to hum pick up. You must keep all sources of AC magnetic fields at least 3 feet away from the K2 or the VFO will be modulated by the hum. This has been noted many times here on the reflector. Even a high intensity lamp too close to the K2 was a problem. Do not stack the K2 on top of a power supply or amplifier or anything with a large power transformer


Don Brown

KD5NDB


  ----- Original Message -----
  From: Tom Althoff<mailto:[hidden email]>
  To: [hidden email]<mailto:[hidden email]>
  Sent: Thursday, October 28, 2004 4:13 PM
  Subject: [Elecraft] Hum coupling?


  Ten-Tec recommended putting the matching speaker/power supply of my old Omni-V on the RIGHT hand side of the radio.  The audio lines ran on the left side and the transformer in the supply caused hum on receive.

  I'm experiencing similar AC hum on the K2 audio.   The K2 sits on top of my Titan II and when the HV is set to operate (kicking in the big HV xfmr directly under the K2) I get the hum.  If I pick the K2 up and move it about 3" away from the Titan then all is well.

  Has anyone else experienced hum from nearby power transformers?   I plan on using a 10Amp analog supply (not here yet) and anticipate I might have to keep it away from the K2.   I suspect switching supplies do not cause the same effect.

  Tom K2TA
  Greenwood Lake, NY
  K2 #1117
  _______________________________________________
  Elecraft mailing list
  Post to: [hidden email]<mailto:[hidden email]>
  You must be a subscriber to post to the list.
  Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft<http://mailman.qth.net/mailman/listinfo/elecraft>    
  Help: http://mailman.qth.net/subscribers.htm<http://mailman.qth.net/subscribershtm>
  Elecraft web page: http://www.elecraft.com<http://www.elecraft.com/>
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft   
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Ron D'Eau Claire-2]

Yep. Not only that, you'll have hum on the transmitted signal a well, Tom.

I think there's a warning in the documentation to keep the K2 a way from
strong transformer fields.

Three years ago I discovered hum on my K2 that went away every time I opened
it up to check things out. Maddening. Hum while operating then no hum while
investigating!

Then I noticed the obvious. I was removing the K2 from its perch on top of
my power supply when I opened it up to look for the source of the hum...

I have an Astron 20 amp for my K2/100 and it sits on a stool UNDER the
operating table. That keeps the table clear for other things and keeps the
AC magnetic field out of the K2.

Ron AC7AC

-----Original Message-----
I'm experiencing similar AC hum on the K2 audio.   The K2 sits on top of my
Titan II and when the HV is set to operate (kicking in the big HV xfmr
directly under the K2) I get the hum.  If I pick the K2 up and move it about
3" away from the Titan then all is well.

Has anyone else experienced hum from nearby power transformers?   I plan on
using a 10Amp analog supply (not here yet) and anticipate I might have to
keep it away from the K2.   I suspect switching supplies do not cause the
same effect.

Tom K2TA
Greenwood Lake, NY
K2 #1117


_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft   
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Stuart Rohre]

Actually, Tom switching supplies may have a worse coupling effect since they
have an oscillator going at higher frequency than the power line, in
addition to power line 60 Hz.

And, even coupling of RF between Tuner and Radio can happen.  At a Field Day
one time, a tuner was placed on a Yaesu transceiver, and did not tune a
dipole well at all.  After some frustration, we discovered there was
magnetic coupling right thru the aluminum case of the tuner from its coil to
the radio's tuned circuits causing an RF feedback.

Moving the tuner from the top of the radio cured all problems.
-Stuart
K5KVH


_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft   
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Brian Mury-3]

> I have an Astron 20 amp for my K2/100 and it sits on a stool UNDER the
> operating table. That keeps the table clear for other things and keeps
> the AC magnetic field out of the K2.

I've also got an Astron 20 amp supply that lives under the desk. You
forgot to mention that it also makes a nice foot warmer on cold
days! ;-)

--
73, Brian
VE7NGR

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft   
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Tom Hammond-3]

Hi Tom:

At 04:13 PM 10/28/04, Tom Althoff wrote:

>Ten-Tec recommended putting the matching speaker/power supply of my old
>Omni-V on the RIGHT hand side of the radio.  The audio lines ran on the
>left side and the transformer in the supply caused hum on receive.
>
>I'm experiencing similar AC hum on the K2 audio.   The K2 sits on top of
>my Titan II and when the HV is set to operate (kicking in the big HV xfmr
>directly under the K2) I get the hum.  If I pick the K2 up and move it
>about 3" away from the Titan then all is well.
>
>Has anyone else experienced hum from nearby power transformers?   I plan
>on using a 10Amp analog supply (not here yet) and anticipate I might have
>to keep it away from the K2.   I suspect switching supplies do not cause
>the same effect.

Yup... same scenario!

Supplies with big trnasformers, or even small ones carrying high current,
can/will often cause hum on the K2.  Best to space them a distance away.

Switchers probably won't induce hum, but might cause in-band birdies by
virtue of their switching frequency and (for some) lack of adequate filtering.

73,

Tom Hammond    N0SS

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft   
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[hank k8dd-2]

At 10/29/2004 10:16 AM, Tom Hammond wrote:


>Supplies with big trnasformers, or even small ones carrying high current,
>can/will often cause hum on the K2.  Best to space them a distance away.
>
>Switchers probably won't induce hum, but might cause in-band birdies by
>virtue of their switching frequency and (for some) lack of adequate filtering.
>
>73,
>
>Tom Hammond    N0SS



OK .... here's the new program!



Supplies with real transformers can cause hum in the K2
Supplies with switching can cause birdies in the K2

What's the option?   No power supply?
No power supply, No hum, No birdies, No problem?
Well, the sensitivity goes to Hell in a handbasket.

The solution?
The new K2-PSQ and K2-PSH

K2-PSQ is a 4 amp power supply to power your K2 with a bit of current to spare.
K2-PSH is a 25 amp power supply to power your K2/100 with a bit of current
to spare.
Both power supplies fit in an enclosure that fits right under your K2 or
K2/100.  How do they do it?  SMT - the new technology.  Brought to you by
the Godzilla PoWer company, Surface Mount Transformers that can deliver up
to 10000 watts of live of power.  In conjunction with Elecraft LLC, and
QRP-L, Godzilla has miniaturized their line of very high power supplies to
fit into the Elecraft KAT-100 1.5" enclosure with 99.89776% regulation
(mandated by qrp-l, and several 6's).
Just send the name of your financial institution and a letter from them
with a line of unlimited credit to ..... well, you get the picture!

Ok ..... wife brought the little white pills to calm me down and said she
will let me go back to the shack for some 40M cw in a short while.  They
tell me I haven't been the same since Godzilla came out with the 3 db per
hundred feet gain special coax.  Guess I never should have ordered that
1000 feet spool!

73    Hank

dam, it's great to be retired and have time to sit back over a coffee and
think ..... and think ...... and think!

*/ INCLUDE DISCLAIMER
Please hold off with your orders until you see the major announcement on
these new products in approximately 150 days or 21 weeks.

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft   
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Daniel Reynolds-2]

Actually - after toasting my internal KBT2 by overcharging with an uncontrolled
solar panel (hint hint... words for the wise) - I bought a $50 MityMite 12Ah
battery/charger from Autozone. I plug it in to charge when I'm not on the air,
and then I unplug the charging cord, and turn on the radio and have RFI free
operation (well - at least free of Power Supply related RFI).

I think Elecraft might do well do design a matching UPS/PS for the K2 & K2/100.
It could utilize a smaller - well designed power supply that acts primarily as
a charger for an internal 25+ Ah battery that is used to power the K2. It could
go into an EC2 enclosure - and possibly have a forward facing speaker and
digital readout of battery voltage readout and/or charger & battery status LEDs
(rapid charge, float charge, low-voltage disconnect). Another option might be a
connection in the back for a solar panel or other 'high voltage DC' input (high
voltage being 15-24V).

- Daniel
AA0NI

--- Hank Kohl K8DD <[hidden email]> wrote:

> OK .... here's the new program!
>
>
>
> Supplies with real transformers can cause hum in the K2
> Supplies with switching can cause birdies in the K2
>
> What's the option?   No power supply?
> No power supply, No hum, No birdies, No problem?
> Well, the sensitivity goes to Hell in a handbasket.
>
> The solution?
> The new K2-PSQ and K2-PSH

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft   
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Stuart Rohre]

The bottom line on placement of rigs to avoid hum for Elecraft, or any other
brand, is to place the transformers and switchers as far from the rigs as
possible within reason.  Use twisted pair leads from DC supplies external to
the rigs, and shield them if possible.

Alternatively (and at great cost) one could buy MuMetal to line a power
supply cabinet on the side toward the rig, but then you have a massive metal
piece blocking venting and cooling of the power supply.

As BPL trials have shown us, Power sources are sources of noise.

Rigs need low noise to have best sensitivity on receivers to work the DX.

DX means distance so keep those supplies at DX.
73
Stuart
K5KVH


_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft   
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com