Jim,
You mention that the TX IMD gets worse when run at 120 watts.
The K3 is specified at 100 watts. If you run at 120 watts, it is
entirely possible that the TX IMD will then not be as specified.
I don't understand why hams expect performance when a transmitter is
pushed beyond it
Don Wilhelm wrote:
Jim,
You mention that the TX IMD gets worse when run at 120 watts.
The K3 is specified at 100 watts. If you run at 120 watts, it is
entirely possible that the TX IMD will then not be as specified.
I don't understand why hams expect performance when a transmitter is
Ian,
Your comment is worthy of consideration, but OTOH, I am of the 'old
school' - amateur radio operators traditionally have not been bound by
power limits imposed by the firmware, and many would be quite displeased
if it were limited in the K3.
We are supposed to share the bands as
I thought as HAMs we would know how to operate a rig within specs and not
rely on manufacturing. I have been an amateur for 49 years and I learned
early on that is was my responsibility to know how to operate and control my
own signals regardless of rigs. That is why we learn theory. We have a
--- On Wed, 1/28/09, Ian Maude i...@gb7mbc.net wrote:
This was what I was saying in my post the other day Don.
If the rig does not have good IMD over 100W and Elecraft say we should not run
it over 100W, why does the radio allow me to turn it up?
IMHO, the power level on SSB should
It's simple,
The manual says this.
Note: The K3 is capable of up to 120 W output on some bands. However,
IMD and spurious products are specified at 100 W. This is the
recommended maximum.
You run your rig out of spec don't complain to Elecraft about it's
performance. Maybe that particular
Don Wilhelm wrote:
Ian,
Your comment is worthy of consideration, but OTOH, I am of the 'old
school' - amateur radio operators traditionally have not been bound by
power limits imposed by the firmware, and many would be quite displeased
if it were limited in the K3.
With respect Don,
Don Wilhelm-4 wrote:
You mention that the TX IMD gets worse when run at 120 watts.
The K3 is specified at 100 watts. If you run at 120 watts, it is
entirely possible that the TX IMD will then not be as specified.
I don't understand why hams expect performance when a transmitter is
- Original Message -
From: Bill W4ZV btipp...@alum.mit.edu
Typical Citizen Band mentality (knobs fully to the right) plus some on
this list are well known QRO types (i.e. VERY big amps need more drive
than
legal amps).
... a remark tossed off by Ian Gillan of Deep Purple during a
With respect Don, it is already limited :) It is limited to 120W. What
is the point of doing that if the radio should not be used at that power?
I can't speak for the K3 designer(s), but not all modes elevate or produce
IM at the upper end of the output power curve. CW is one such mode,
27, 2009 11:09 PM
Subject: Re: [Elecraft] K3/100 input voltage and TX IMD
A solid state linear RF PA will generate more IMD if the supply voltage sags
on current peaks. How much distortion vs voltage change depends on the
amplifier design and components used.
Someone reported here
It would be interesting to check the voltage drop from the APP on the K3
to the cathode of D11 ( component of KPA3) when under a 100 watt load. 73
Gil K8EAG
Cascading APP connectors can add up to relevant IR loss. For example, in
my installation, the power supply and a 55-AH gel-cell
Have you measured the transient response time? Should be easy to see a 1V
transient with a modest scope.
David
G3UNA
It would be interesting to check the voltage drop from the APP on the K3
to the cathode of D11 ( component of KPA3) when under a 100 watt load. 73
Gil K8EAG
Cascading
I did my own little unscientific IMD check yesterday. I connected the
K3 to my Cantenna and monitored with my IC-706IIg on the same desk and
same power supply. I used a bit of wire in the 706's antenna terminal
sufficient to give an S9 or higher received signal strength. Had the K3
at 100
If they do that (limit SSB power to 100W) they really should vary the
limit based on power supply voltage. For example, the K3 is specified
down to 11V, but you can't get 100W at that voltage. If you try you'll
get horrible distortion. It's up to the operator to be aware of these
limitations
A solid state linear RF PA will generate more IMD if the supply voltage sags
on current peaks. How much distortion vs voltage change depends on the
amplifier design and components used.
Someone reported here that he increased the supply voltage a bit and noted a
1 to 2 dB reduction in TX IMD.
Rick,
It sounds like you have a good low resistance connection with each
connection as tight as it can be.
That voltage drop is about the best you can do. If I calculate the
resistance of a 12 gauge cable 5 feet long, it is 8.1 mv for each
conductor. The APP connector contact resistance is a
I rearranged things to shorten up the K3 supplied cable to 3'.
The difference between just the RX ON (1.11 amps) and 100 watts (18.77 amps)
ended up being 0.6 volts. Supply is an Astron 20A.
Previously with a 6' cable the difference was 1 Volt.
Interesting thing is the current draw at each
Rick, and others
Just to clarify things a bit.
First of all when I did get the bad IMD report on the
air I was at a different QTH and used a another PS, in
this case I do not know exactly what voltage K3 got or
voltage drop.
Then I did bring K3 home to a PS that had 13.9V RX and
13.5V at TX,
Jan
Perhaps you could share with us all the ideas and adjustments you made.
David
G3UNA
Rick, and others
Received some good ideas from some nice people here on the
reflector. That together with some studies of my own
led to bias adjustment on the KPA100
20 matches
Mail list logo
