Actually, you will probably LOSE a couple of db by switching on both
preamp and attenuator compared to having both switched off. (Measure
your MDS and compare results if you don't believe...)
Regarding weak signals, one factor that is overlooked is the ATU. By
switching it to bypass you can gain
Why do you think you gain in MDS (presumably you mean a *lower* MDS) by
bypassing the ATU? If the ATU is needed for transmit, it will also be
benficial in receive. I don't have the K3 ATU, but both manual and automatic
tuners in my antenna system and can certainly certify that when switching in
Actually, you will probably LOSE a couple of db by switching on both
preamp and attenuator compared to having both switched off. (Measure
your MDS and compare results if you don't believe...)
MDS, like dynamic range, can go either direction with changes in gain. It is
possible to have a gain
As Tom said.
The cause of the signal gain when using a tuner is really a matter of
having a badly matched situation without the tuner.
In the old days (with manual tuners!), it was easy to demonstrate how a
mismatched load seen by the RX degrades signal.
Just start with random tuner settings.
You are right about the ATU. It was my mistake comparing the ATU-ON
which had been tuned at other than 50 ohm load compared to the
ATU-OFF.
As for PRE+ATT, I just measured MDS with the PRE and ATT settings
either both on or both off. Having both PRE and ATT switched on gives
2 db poorer MDS
The K3 ATU is not removed from the circuit when it is set to bypass. It is set
to
compensate for stray reactance in traces, etc. so that the SWR will be close to
1:1 for a
true 50 ohm load.
So any variations in MDS are not caused by losses inherent in the tuner.
On 8/11/2010 6:34 AM, Tom
were
described in the following manner: A Bug is an Undocumented Feature.
Jim KD5VXH
- Original Message -
From: ab2tc ab...@arrl.net
To: elecraft@mailman.qth.net
Sent: Wednesday, August 11, 2010 8:21 AM
Subject: Re: [Elecraft] K3: PRE/ATT Bug or feature
on and off when I need
it.
From: drew...@verizon.net
To: ab...@arrl.net
Date: Wed, 11 Aug 2010 10:16:40 -0400
CC: Elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3: PRE/ATT Bug or feature?
You are right about the ATU. It was my mistake comparing the ATU-ON
which had been tuned at other
Oof. Having the attenuator and preamp on at the same time is completely
nonsensical. The gain of the preamp is ~11 dB and the loss of the attenuator
is ~10dB so they almost completely cancel each other out gainwise. But *all*
the noise from the preamp will be added, so your noise floor will be
-boun...@mailman.qth.net] On Behalf Of ab2tc
Sent: Wednesday, August 11, 2010 3:50 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3: PRE/ATT Bug or feature?
Oof. Having the attenuator and preamp on at the same time is completely
nonsensical. The gain of the preamp is ~11 dB and the loss
My K3 (SN 1069, fw 4.03) has always exhibited the ability to have PRE and ATT
on simultaneously. If one engages ATT by a long hold, then hits PRE with a tap
(same button), the display shows both functions engaged. The converse is true
too, i.e. PRE engaged with a tap, followed by ATT with a
Bill,
Normal operation. The attenuator is -10 dB and the preamp is +12 dB.
So if you only need +2 dB of preamp, turning both on will give it to you.
73,
Don W3FPR
Bill McDowell wrote:
My K3 (SN 1069, fw 4.03) has always exhibited the ability to have PRE and ATT
on simultaneously. If one
Sent: Tuesday, August 10, 2010 8:47 AM
Subject: Re: [Elecraft] K3: PRE/ATT Bug or feature?
Bill,
Normal operation. The attenuator is -10 dB and the preamp is +12 dB.
So if you only need +2 dB of preamp, turning both on will give it to you.
73,
Don W3FPR
Bill McDowell wrote:
My K3 (SN
for finding weak signals
in a loud noise floor.
Date: Tue, 10 Aug 2010 08:31:15 -0400
From: k4...@earthlink.net
To: elecraft@mailman.qth.net
Subject: [Elecraft] K3: PRE/ATT Bug or feature?
My K3 (SN 1069, fw 4.03) has always exhibited the ability to have PRE and ATT
on simultaneously
:
This is NOT a bug, this is working EXACTLY as it should [...]
From: k4...@earthlink.net
Subject: [Elecraft] K3: PRE/ATT Bug or feature?
My K3 (SN 1069, fw 4.03) has always exhibited the ability to have
PRE and ATT on simultaneously
...@embarqmail.com
To: Bill McDowell k4...@earthlink.net
Cc: elecraft reflector elecraft@mailman.qth.net
Sent: Tuesday, August 10, 2010 8:47 AM
Subject: Re: [Elecraft] K3: PRE/ATT Bug or feature?
Bill,
Normal operation. The attenuator is -10 dB and the preamp is +12 dB.
So if you only need +2 dB
This is NOT a bug, this is working EXACTLY as it should. Some time you
want to have a little extra gain, but not as much as the Pre does alone.
In this case you will run the Pre ON, and the ATT on at the same time. No
bug there. Just another way Elecraft has made the K3 a versatile rig
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