[Elecraft] IMD and supply voltage

[jim]

How about 80 watts instead.

Won't make a noticeable difference on the receive end.

Even better, get rid of all the Yaesu and Icom "Clackers" with their VERY
poor CW performance.  You can have the best class A amplifier in the world,
but garbage in will always equal garbage out.

I am ashamed at our "leaders" at the ARRL for not petitioning the FCC for
better specs.  The technology is there, they all use it in their business
radios that have a better spec.

Oh, I forgot, follow the money and take the advertising monies from these
clackers

Jim
W6AIM




-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Don
Wilhelm
Sent: Thursday, October 29, 2015 7:41 AM
To: frank; elecraft at mailman.qth.net
Subject: Re: [Elecraft] IMD and supply voltage

Frank,

I think the "issue" is one of some hams wanting to make what is good already
into something better.
If you look closely you should discover that this is a situation common to
*all* 100 watt class amplifiers that are supposed to run on a nominal
'12 volt' supply.  That voltage level is chosen because it is common for
vehicle batteries, so most transceivers are designed around that voltage
- the K3S is just one of those.

Using an increased voltage power supply will drastically reduce the transmit
IMD, and that is true for all those 100 watt class amplifiers.
Bottom line is that I don't think it will be "fixed" in the K3S - I don't
think it can be fixed in any of the 100 watt class solid state amplifiers.

So the thing to do is to run the power supply voltage up to near 15 volts
(but not above), and do not operate with "all knobs to the right".
Many hams seen to want to squeeze all the power output that they can from a
transceiver, so you will put a cleaner signal on the air if you set the
power to 100 watts rather than trying to squeeze that last 20 extra watts
out of an amplifier.

73,
Don W3FPR

On 10/29/2015 11:09 AM, frank wrote:
> This subject keeps cropping up.  Is this a serious issue ?
>
> I have heard that IMD improves by 10db with a one volt increase in supply
voltage.  Is this really the case or just a measurement error?  10db is a
large difference.  One volt is a small variation.
>
> What is the minimum acceptable IMD?  How linear does the amp need to be?
If 36db is better than 26db is 100db even better or just overkill?
>
> Are other solid state amplifier products similarly effected?
>
> What is the IMD performance of the K3S at 10 watts over a supply voltage
variation from 11 volts to 14.7 volts?  I ask because I believe those ten
watts are generated by Dmos devices as well.  Do these devices only
misbehave with varying supply voltage at higher (100w) power levels and
lower supply voltages?
>
> Should I wait to purchase a K3S until this issue is resolved?  (Assuming
this is a valid issue)
>
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to jbollit at outlook.com