KPA500 audio muffled?

[Joe Word]

Chuck,

I had muffled audio reports while using a Tokyo Hi Power 1.2Kfx amp.
It has coming from RF getting into the amp. THP wrote it off, saying
nothing they could (would) do about it because I was on the second
floor. But... I now have a KPA-500 and have no problems on any band at
any power level.

Just a thought!

Joe  N9VX

--------------------------------------------------------------------------------------------------------------------
I have gotten a few reports of sounding like my audio is muffled as compared
to running the K3 alone. It is true that with several listeners in different
states, there is not a consensus of opinion on that. Some of the guys think
it sounds just fine, and some say they can hear a slight muffled sound with
the KPA turned on. The point of comparing it to K3 only and K3 with KPA500
is that the mic is not in the equation. The report is clearly that the amp
sounds muffled. Not unreadable, just slightly muffled.
I have a bias current of 0.4A...about the only thing I can think of to
check. I think there was some discussion of setting the bias current here,
but I can't find it again. What is the range of bias current for best
linearity? I don't see any help in the manual.

-----
Chuck, KE9UW
--
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[John Lemay]

Chuck

I agree with Joe's diagnosis. Try an experiment:-

Run 100w from the K3 alone and get a report. Then turn back the power so
that K3 plus amplifier is producing 100w. See if the report is now OK, or
muffled.

If the report is OK, it could be RF feedback which only occurs at high
power. If the report is muffled you might have an amplifier problem.

John G4ZTR

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Joe Word
Sent: 15 November 2011 18:52
To: [hidden email]
Subject: [Elecraft] KPA500 audio muffled?

Chuck,

I had muffled audio reports while using a Tokyo Hi Power 1.2Kfx amp.
It has coming from RF getting into the amp. THP wrote it off, saying
nothing they could (would) do about it because I was on the second
floor. But... I now have a KPA-500 and have no problems on any band at
any power level.

Just a thought!

Joe  N9VX

----------------------------------------------------------------------------
----------------------------------------
I have gotten a few reports of sounding like my audio is muffled as compared
to running the K3 alone. It is true that with several listeners in different
states, there is not a consensus of opinion on that. Some of the guys think
it sounds just fine, and some say they can hear a slight muffled sound with
the KPA turned on. The point of comparing it to K3 only and K3 with KPA500
is that the mic is not in the equation. The report is clearly that the amp
sounds muffled. Not unreadable, just slightly muffled.
I have a bias current of 0.4A...about the only thing I can think of to
check. I think there was some discussion of setting the bias current here,
but I can't find it again. What is the range of bias current for best
linearity? I don't see any help in the manual.

-----
Chuck, KE9UW
--
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

__________ Information from ESET NOD32 Antivirus, version of virus signature
database 6632 (20111115) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com


 

__________ Information from ESET NOD32 Antivirus, version of virus signature
database 6632 (20111115) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com
 

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html