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K3 on Order

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David Guernsey

K3 on Order

I have an Astron RS-35M as my power supply through a Rigrunner to my K3/10.
Enough left to upgrade to K3/100.

73s de Dave KJ6CBS

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Steve Ellington

Re: K3 battery power

Is anyone using full time battery power and trickle charging?
Considering the high price of power supplies and the security of a full time
backup system, it would seem to make sense. The K3 draws so little current
on receive that it would make sense to run it this way. I would be a bit
concerned about gas from the battery however.
Currently I use an Astron 35m and I love it but I just bet that it consumes
more power than the K3! Perhaps the battery/charger concept would be more
efficient?
Steve
N4LQ
----- Original Message -----
From: "David Guernsey" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, July 15, 2010 8:32 PM
Subject: [Elecraft] K3 on Order

>I have an Astron RS-35M as my power supply through a Rigrunner to my K3/10.
> Enough left to upgrade to K3/100.
>
> 73s de Dave KJ6CBS
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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>
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Steve Ellington

Re: K3 battery power

I'm wondering what to use for battery power. The K3 requires 13.8v. I would
like to use a typical golf cart battery and a charger but am concerned about
the voltage from the charger being too high and possible switching noise.
I've seen some QST articles showing DIY projects but those are rather
involved. Does anyone make a charger/controller that you can just plug in
and not worry about over-voltage?
Steve
N4LQ
----- Original Message -----
From: "Jack Colson" <[hidden email]>
To: "Steve Ellington" <[hidden email]>
Sent: Thursday, July 15, 2010 9:52 PM
Subject: Re: [Elecraft] K3 battery power

>I did that for many years on the W3VD beacons. The battery was in a
>building but very rarely visited by humans. Worked great. The Astron
>RS-35 is not a good choice. I was using on and even without a load the
>case is warm. I am now using SS-25M for my K3 and it runs cool.
> 73
> Jack, W3TMZ
> ----- Original Message -----
> From: "Steve Ellington" <[hidden email]>
> To: "David Guernsey" <[hidden email]>; <[hidden email]>
> Sent: Thursday, July 15, 2010 9:32 PM
> Subject: Re: [Elecraft] K3 battery power
>
>
>> Is anyone using full time battery power and trickle charging?
>> Considering the high price of power supplies and the security of a full
>> time
>> backup system, it would seem to make sense. The K3 draws so little
>> current
>> on receive that it would make sense to run it this way. I would be a bit
>> concerned about gas from the battery however.
>> Currently I use an Astron 35m and I love it but I just bet that it
>> consumes
>> more power than the K3! Perhaps the battery/charger concept would be more
>> efficient?
>> Steve
>> N4LQ
>> ----- Original Message -----
>> From: "David Guernsey" <[hidden email]>
>> To: <[hidden email]>
>> Sent: Thursday, July 15, 2010 8:32 PM
>> Subject: [Elecraft] K3 on Order
>>
>>
>>>I have an Astron RS-35M as my power supply through a Rigrunner to my
>>>K3/10.
>>> Enough left to upgrade to K3/100.
>>>
>>> 73s de Dave KJ6CBS
>>>
>>>
>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
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>>> Please help support this email list: http://www.qsl.net/donate.html
>>>
>>
>> ______________________________________________________________
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>

Don Wilhelm-4

Re: K3 battery power

Steve,

Yes indeed - Look at the chargers from A&A Engineering
http://www.a-aengineering.com/. Depending on your battery and the loads
connected to it, you may want the 5 amp Smartcharger, but if you are not
transmitting a lot and do not have the subreceiver installed, the 1 amp
may do for you.
These are linear Smartcharger that use the UC3906 controller rather than
pulse width control, and they create no detectable noise.
I have one modified for 250 ma. that has been connected to my QRP K2
with internal SLA battery for years. The K2 always runs on the battery
and the Smartcharger replenishes the internal battery. Works swell for me.

73,
Don W3FPR

Steve Ellington wrote:
> I'm wondering what to use for battery power. The K3 requires 13.8v. I would
> like to use a typical golf cart battery and a charger but am concerned about
> the voltage from the charger being too high and possible switching noise.
> I've seen some QST articles showing DIY projects but those are rather
> involved. Does anyone make a charger/controller that you can just plug in
> and not worry about over-voltage?
>
>
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Augie "Gus" Hansen

Re: K3 battery power

In reply to this post by Steve Ellington

On 7/15/2010 7:32 PM, Steve Ellington wrote:
> Is anyone using full time battery power and trickle charging?
>

I have two deep cycle batteries kept topped off by about 60 watts of
solar panel and a FlexCharge NC25 charge controller. Usually one battery
is on charge while the other is in the shack (or field) powering the K3.

During Field Day operation and longer contest periods at 100 watts, 50%
RX/TX, the battery voltage has never dropped below 11.5 volts from a
fully charged condition. In intermittent service (2-3 hours daily) the
battery easily lasts for more than a week, often two before requiring a
charge.

Gus Hansen
KB0YH

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ussv dharma

Re: K3 battery power

In reply to this post by Steve Ellington

Strongly suggest you look at tech data for "Mr. Solar", MPPT charge regulator before you do anything with batteries/chargers/solar panels.

New Technology...sure does fine job on my full time live aboard boat

Grandmaw susan

If you don't change direction you WILL arrive exactly where you're headed!! Susan Meckley, Skipper W7KFI-mm AFA9SM USSV DHARMA

--- On Thu, 7/15/10, Steve Ellington <[hidden email]> wrote:

> From: Steve Ellington <[hidden email]>
> Subject: Re: [Elecraft] K3 battery power
> To: "David Guernsey" <[hidden email]>, [hidden email]
> Date: Thursday, July 15, 2010, 3:32 PM
> Is anyone using full time battery
> power and trickle charging?
> Considering the high price of power supplies and the
> security of a full time
> backup system, it would seem to make sense. The K3 draws so
> little current
> on receive that it would make sense to run it this way. I
> would be a bit
> concerned about gas from the battery however.
> Currently I use an Astron 35m and I love it but I just bet
> that it consumes
> more power than the K3! Perhaps the battery/charger concept
> would be more
> efficient?
> Steve
> N4LQ
> ----- Original Message -----
> From: "David Guernsey" <[hidden email]>
> To: <[hidden email]>
> Sent: Thursday, July 15, 2010 8:32 PM
> Subject: [Elecraft] K3 on Order
>
>
> >I have an Astron RS-35M as my power supply through a
> Rigrunner to my K3/10.
> > Enough left to upgrade to K3/100.
> >
> > 73s de Dave KJ6CBS
> >
> >
> >
> >
> >
> ______________________________________________________________
> > 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
> >
>
> ______________________________________________________________
> Elecraft mailing list
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>

Augie "Gus" Hansen

Re: K3 battery power

In reply to this post by Steve Ellington

On 7/15/2010 8:03 PM, Steve Ellington wrote:
> I'm wondering what to use for battery power. The K3 requires 13.8v.
>

From the K3 spec:
Supply voltage 13.8V nominal (11V min, 15V max.)

I routinely run the K3 on battery as note in my previous post and the
voltage averages 12-12.5V and falls below 12V only during contests. The
BAT MIN setting remains at the default of 11V, which was reached only
once during a test with a variable voltage supply.

Gus Hansen
KB0YH
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P.B. Christensen

Re: K3 battery power

In reply to this post by Steve Ellington

Steve,

If you use a station power supply as both a power source and charger, you'll
want to investigate methods for isolating the battery from the power
supply/charging source. I've been using a West Mountain Super PowerGate
device with an Optima Blue, gelled 80A marine battery.

http://www.westmountainradio.com/SuperPWRgate.htm

The PowerGate is an instant-switching device and can be configured to work
with gelled, AGM or lead-acid batteries. It uses three ports: (1) battery;
(2) power supply; and (3) common output, each using an Anderson Powerpole
connector. The output of my PowerGate is connected to a 12-port RigRunner
power manifold for distribution to all the +12V shack equipment.

Paul, W9AC

----- Original Message -----
From: "Steve Ellington" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, July 15, 2010 10:03 PM
Subject: Re: [Elecraft] K3 battery power

> I'm wondering what to use for battery power. The K3 requires 13.8v. I
> would
> like to use a typical golf cart battery and a charger but am concerned
> about
> the voltage from the charger being too high and possible switching noise.
> I've seen some QST articles showing DIY projects but those are rather
> involved. Does anyone make a charger/controller that you can just plug in
> and not worry about over-voltage?
> Steve
> N4LQ

Steve Ellington

Re: K3 battery power

That PowerGate looks nice however I was thinking about eliminating the power
supply and running only off battery power. A trickle charger would charge it
overnight. That would eliminate the power wasting DC supply.
I was looking at the MFJ4416 battery booster to keep the supply V at 13.8
too.

Steve
N4LQ
----- Original Message -----
From: "Paul Christensen" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, July 15, 2010 10:50 PM
Subject: Re: [Elecraft] K3 battery power

> Steve,
>
> If you use a station power supply as both a power source and charger,
> you'll
> want to investigate methods for isolating the battery from the power
> supply/charging source. I've been using a West Mountain Super PowerGate
> device with an Optima Blue, gelled 80A marine battery.
>
> http://www.westmountainradio.com/SuperPWRgate.htm
>
> The PowerGate is an instant-switching device and can be configured to work
> with gelled, AGM or lead-acid batteries. It uses three ports: (1)
> battery;
> (2) power supply; and (3) common output, each using an Anderson Powerpole
> connector. The output of my PowerGate is connected to a 12-port RigRunner
> power manifold for distribution to all the +12V shack equipment.
>
> Paul, W9AC
>
> ----- Original Message -----
> From: "Steve Ellington" <[hidden email]>
> To: <[hidden email]>
> Sent: Thursday, July 15, 2010 10:03 PM
> Subject: Re: [Elecraft] K3 battery power
>
>
>> I'm wondering what to use for battery power. The K3 requires 13.8v. I
>> would
>> like to use a typical golf cart battery and a charger but am concerned
>> about
>> the voltage from the charger being too high and possible switching noise.
>> I've seen some QST articles showing DIY projects but those are rather
>> involved. Does anyone make a charger/controller that you can just plug in
>> and not worry about over-voltage?
>> Steve
>> N4LQ
>
> ______________________________________________________________
> 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
>

n7ws

Re: K3 battery power

In reply to this post by Steve Ellington

I'm sure that I've mentioned this before, probably more than once.

I have an UPS/emergency power supply consisting of a East Penn (Deka) 95 AH AGM battery on continuous charge via a homemade "smart charger."

The charger was constructed using an Astron 35M supply, gutted of the regulator board, retaining the series pass transistors, transformer, rectifier and filter capacitor. The control board is an A&A Engineering piece.

I originally built this to run my travel trailer, replacing a switching mode supply that made radio and TV reception (pre-digital) impossible. I have since brought it into the shack. Outgassing is not an issue with the AGM battery.

In addition I use an in-line boost regulator at all times. Clearly this is not cheaper than an Astron supply since one is used, but it will run the K3 while on mains power without discharging the battery whatsoever. So I retain full capacity in the event of a power failure. Backup to this is a Honda EU2000 outside the shack.

This is also my Field Day setup.

Clearly, this is not what you had in mind, but my position is that the battery should be babied for long life. Others may consider them throwaway items, that can be routinely replaced. This isn't a bad approach monetarily speaking, but a failure while calling P5 will make one wonder about this approach.

Wes N7WS

--- On Thu, 7/15/10, Steve Ellington <[hidden email]> wrote:

From: Steve Ellington <[hidden email]>

Is anyone using full time battery power and trickle charging?
Considering the high price of power supplies and the security of a full time
backup system, it would seem to make sense. The K3 draws so little current
on receive that it would make sense to run it this way. I would be a bit
concerned about gas from the battery however.
Currently I use an Astron 35m and I love it but I just bet that it consumes
more power than the K3! Perhaps the battery/charger concept would be more
efficient?
Steve
N4LQ
----- Original Message -----
From: "David Guernsey" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, July 15, 2010 8:32 PM
Subject: [Elecraft] K3 on Order

>I have an Astron RS-35M as my power supply through a Rigrunner to my K3/10.
> Enough left to upgrade to K3/100.
>
> 73s de Dave KJ6CBS
>

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Larry 'Rebar' Rebarchik - N6CCH

Re: K3 battery power

In reply to this post by Steve Ellington

There is a mod for the Astron to set it up to float charge the battery
with a little cut to the PCB trace and a 10K resistor.
I have my shack setup with four 55Ah SLAs in parallel to the Astron. We
ran my K3 on FD with a single 55Ah SLA and made around 80 or possibly 100+
QSOs at 100W until I realized the Solar charged 55Ah battery was connected,
but the PS was not on.

See the following URL for the Astron MOD details;

http://www.arrl.org/attachments/view/User/50572
or the source at;
https://ntc.cap.af.mil/RS_Battmod.cfm

rebar

On Thu, 15 Jul 2010 21:32:08 -0400, "Steve Ellington"
<[hidden email]> wrote:
> Is anyone using full time battery power and trickle charging?
> Considering the high price of power supplies and the security of a full
> time
> backup system, it would seem to make sense. The K3 draws so little
current
> on receive that it would make sense to run it this way. I would be a bit

> concerned about gas from the battery however.
> Currently I use an Astron 35m and I love it but I just bet that it
> consumes
> more power than the K3! Perhaps the battery/charger concept would be
more
> efficient?
> Steve
> N4LQ

--
73 de N6CCH aka Rebar
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Jim Brown-10

Re: K3 battery power

In reply to this post by Steve Ellington

On Thu, 15 Jul 2010 21:32:08 -0400, Steve Ellington wrote:

>Is anyone using full time battery power and trickle charging?

Sure -- since about 2004, I've run all the gear in my shack from a big
12V deep discharge battery that is float-charged by a $10 dollar no-
name supply that I bought at a hamfest. Now that I'm running SO2R, I
have two batteries and two chargers. Everything is wired in parallel.
All the gear is quite happy. It's a big on-line 12V UPS. :) In addition
to the K3s, the 12V bus runs a VHF/UHF transceiver, power amps for that
rig, 12v lights in my Ten Tec antenna tuners, and an AM/FM car radio
that plays the local jazz station when I'm not hamming. :)

I have no isolation at all between the power supplies and the
batteries, but I do have a DC Ammeter in line between one of the power
supplies and its battery as a sort of sanity check. The voltmeter built
into the K3s tells me that the power supplies are regulated to 14V, and
don't overcharge the batteries. The only things that doesn't run on
this 12V system are the computer and the power amps (which run on
240VAC). The computers are Thinkpads with good batteries. If I had to,
I could run the Thinkpads from that 12V system.

We live in the Santa Cruz Mountains, where it's common to lose power,
sometimes for the better part of a day. This UPS system protects me
from that quite well. It's also great for Field Day -- you don't go
down when the generator is shut down for refueling.

73, Jim K9YC

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Fw: K3 battery power

In reply to this post by Steve Ellington

This does not exactly address your question, but I am using a JTPS 35 BCM with a
marine type pseudo deep cycle battery. The K3 runs at 13.8V from the power
supply when the power is on and the battery is trickle charged. When the power
drops the JTPS switches to the battery and supplies slightly more than 12 volts
to the K3. You will not notice the swap when in receive and if you have good
connections you will not notice it in transmit either (except your desk lamp
will go out and you amp won't work. The K3 seems to work fine down to about
11.0 volts but I don't know about the IMD. I recommend reducing power when on
battery to 50 watts or less to minimize the loss through the connectors. The K3
will shut down when you have drained your battery, but I have never observed
that during a power out, just in testing without the battery and turning down
the voltage on the power supply. The K3 operates much better at low voltage
than the other transceivers that I have tried.

I don't see how you can save money with a battery and trickle charger over a
power supply when you can get good power supplies as low as $99.95. A good
battery is about $80 and a good charger maybe $50 unless you have better sources
than I have. The low voltage operation would be helpful if you desire a solar
charged battery system because a special 8 cell battery system to furnish 14
volts is not required. You can use regular car, boat or RV batteries with their
limited ability for deep cycle or pay the higher price for a true deep cycle
battery if you have the deep pocket that makes that possible.
Willis 'Cookie' Cooke
K5EWJ

________________________________
From: Steve Ellington <[hidden email]>
To: David Guernsey <[hidden email]>; [hidden email]
Sent: Thu, July 15, 2010 8:32:08 PM
Subject: Re: [Elecraft] K3 battery power

Is anyone using full time battery power and trickle charging?
Considering the high price of power supplies and the security of a full time
backup system, it would seem to make sense. The K3 draws so little current
on receive that it would make sense to run it this way. I would be a bit
concerned about gas from the battery however.
Currently I use an Astron 35m and I love it but I just bet that it consumes
more power than the K3! Perhaps the battery/charger concept would be more
efficient?
Steve
N4LQ
----- Original Message -----
From: "David Guernsey" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, July 15, 2010 8:32 PM
Subject: [Elecraft] K3 on Order

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KM5Q

Re: K3 battery power

In reply to this post by Steve Ellington

Steve,

You can run the K3 directly from a battery, with or without a charger
running, and it will deliver full power within the supply range of
11-15V. You do NOT need a "booster" to supply 13.8V. We had consistent
agreement on this some months back in a similar thread.

As voltage goes down, the K3 draws proportionally more current to
deliver the watts you desire. That's the same thing the voltage
booster does. It's another built-in feature of the K3.

One caution that is not adequately covered in the manual is the
importance of wire size. If #10 AWG wire is more than about 4 feet
distance (8 feet total), its voltage drop may reach or exceed 1V. Keep
it very short, or go to larger wire as you can determine from a wire
size chart.

Also, when choosing a battery charger or charge controller, be sure it
is compatible for the type of battery, either sealed or flooded type.
They require different max. set points. Most sophisticated charger
systems have a setting or adjustment for the type of battery.

Windy KM5Q
K3 #764

> That PowerGate looks nice however I was thinking about eliminating
> the power
> supply and running only off battery power. A trickle charger would
> charge it
> overnight. That would eliminate the power wasting DC supply.
> I was looking at the MFJ4416 battery booster to keep the supply V at
> 13.8
> too.
>
> Steve
> N4LQ

Joe Subich, W4TV-4

Re: K3 battery power

> As voltage goes down, the K3 draws proportionally more current to
> deliver the watts you desire. That's the same thing the voltage
> booster does. It's another built-in feature of the K3.

Unfortunately, this does not apply to transmit IMD. Since the K3
(like all other solid state transmitters) has a fixed ratio broad-
band transformer between the final FETs and the 50 Ohm output.

As the voltage falls and current increases, the amplifier impedance
changes (decreases), the final amplifier operates into an increasing
mismatch and the IMD becomes worse. Keeping the voltage to the
final amplifier as high as possible within its specification allows
the lowest possible IMD and highest efficiency.

73,

... Joe, W4TV

On 7/20/2010 1:34 PM, KM5Q wrote:

> Steve,
>
> You can run the K3 directly from a battery, with or without a charger
> running, and it will deliver full power within the supply range of
> 11-15V. You do NOT need a "booster" to supply 13.8V. We had consistent
> agreement on this some months back in a similar thread.
>
> As voltage goes down, the K3 draws proportionally more current to
> deliver the watts you desire. That's the same thing the voltage
> booster does. It's another built-in feature of the K3.
>
> One caution that is not adequately covered in the manual is the
> importance of wire size. If #10 AWG wire is more than about 4 feet
> distance (8 feet total), its voltage drop may reach or exceed 1V. Keep
> it very short, or go to larger wire as you can determine from a wire
> size chart.
>
> Also, when choosing a battery charger or charge controller, be sure it
> is compatible for the type of battery, either sealed or flooded type.
> They require different max. set points. Most sophisticated charger
> systems have a setting or adjustment for the type of battery.
>
> Windy KM5Q
> K3 #764
>
>
>> That PowerGate looks nice however I was thinking about eliminating
>> the power
>> supply and running only off battery power. A trickle charger would
>> charge it
>> overnight. That would eliminate the power wasting DC supply.
>> I was looking at the MFJ4416 battery booster to keep the supply V at
>> 13.8
>> too.
>>
>> Steve
>> N4LQ
> ______________________________________________________________
> Elecraft mailing list
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n7ws

Re: K3 battery power

Joe took the words right out of my mouth.

Personally, I use an "unnecessary" boost regulator when on battery power or a PS set to at least 14V otherwise.

Of course if you want to annoy your fellow hams, go ahead and run your
K3 on 11V.

I don't know who the "we" were, but it didn't include me.

Wes N7WS

--- On Tue, 7/20/10, Joe Subich, W4TV <[hidden email]> wrote:

> As voltage goes down, the K3 draws proportionally more current to
> deliver the watts you desire. That's the same thing the voltage
> booster does. It's another built-in feature of the K3.

Unfortunately, this does not apply to transmit IMD. Since the K3
(like all other solid state transmitters) has a fixed ratio broad-
band transformer between the final FETs and the 50 Ohm output.

As the voltage falls and current increases, the amplifier impedance
changes (decreases), the final amplifier operates into an increasing
mismatch and the IMD becomes worse. Keeping the voltage to the
final amplifier as high as possible within its specification allows
the lowest possible IMD and highest efficiency.

73,

... Joe, W4TV

On 7/20/2010 1:34 PM, KM5Q wrote:

hank_stamper

Re: K3 battery power

On Jul 20, 2010, at 9:00 PM, Wes Stewart wrote:

> Joe took the words right out of my mouth.
>
> Personally, I use an "unnecessary" boost regulator when on battery
> power or a PS set to at least 14V otherwise.
>
> [snip]
> Unfortunately, this does not apply to transmit IMD. Since the K3
> (like all other solid state transmitters) has a fixed ratio broad-
> band transformer between the final FETs and the 50 Ohm output.
>
> As the voltage falls and current increases, the amplifier impedance
> changes (decreases), the final amplifier operates into an increasing
> mismatch and the IMD becomes worse. Keeping the voltage to the
> final amplifier as high as possible within its specification allows
> the lowest possible IMD and highest efficiency.
>
> 73,
>
> ... Joe, W4TV
>

Interesting. I run a K3 off a couple of pseudo deep cycle 12 volt
batteries with an Iota smart charger hooked up. I run mostly digital
so IMD is important to me. The Iota runs between 13.1 and 13.6 volts
by my K3's meter. Would the difference between that and 14 volts make
a meaningful difference in the IMD ? What brand and model booster
provides 14 volts? The MFJ promises 13.8.

TIA

73 de Eric, KG6MZS

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n7ws

Re: K3 battery power

I'm using a TGE (N8XJK designed) boost regulator on my battery-powered setup. By the K3 meter (when I get time I'll verify this) the supply voltage on receive is 14.1 and on TX ~18A load, it's 13.8.

I have run some preliminary tests (better to follow when time permits) of the IMD performance v. supply voltage v. output power and the results aren't unexpected, although not yet a stable as I would like. IMD goes up with power level and reduced supply voltage. No surprise.

So, absent more definitive answers, I'm personally erring in the direction of theory and preliminary results and keeping the voltage as high as is reasonable and arguing against operating at 11V just because the spec says that's acceptable.

BTW, about 40 years ago, I did some moonlighting for the founders of Iota. My HB analog smart charger that's now in the shack was originally built to replace a horribly noisy switcher in my travel trailer. I've since installed an Iota in the trailer. Good stuff.

Wes N7WS
Interesting. I run a K3 off a couple of pseudo deep cycle 12 volt
batteries with an Iota smart charger hooked up. I run mostly digital
so IMD is important to me. The Iota runs between 13.1 and 13.6 volts
by my K3's meter. Would the difference between that and 14 volts make
a meaningful difference in the IMD ? What brand and model booster
provides 14 volts? The MFJ promises 13.8.

TIA

73 de Eric, KG6MZS

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Phil Salas

Re: K3 battery power

In reply to this post by hank_stamper

"What brand and model booster
provides 14 volts? The MFJ promises 13.8."

I know that the MFJ booster has a pot that lets you set the output voltage
(I have a MFJ-4416B). I'm pretty sure that TGE does as well.

Phil - AD5X

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W8JI

Re: K3 battery power

In reply to this post by hank_stamper

> Interesting. I run a K3 off a couple of pseudo deep cycle 12 volt
> batteries with an Iota smart charger hooked up. I run mostly digital
> so IMD is important to me. The Iota runs between 13.1 and 13.6 volts
> by my K3's meter. Would the difference between that and 14 volts make
> a meaningful difference in the IMD ?

It makes a difference when I test amplifiers at a constant power. I have not
tested a K3, but I would be really amazed if it was not noticeably affected
by reduced voltage.

The problem is worse than an impedance mismatch. The problem is the loadline
of the transistor. You can't get as much swing in the output device without
getting into a non-linear part of the curve.

It would take some compelling proof for me to believe reducing voltage does
not hurt IM performance. In general the notion that all we need to do is let
the rig draw more current to make up for low voltage is misplaced.

It would also be very important to be sure the booster to stay at the
voltage under full load.

73 Tom

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