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RE; How well does the K3 work with lower power supply voltage . . .

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John Kountz

RE; How well does the K3 work with lower power supply voltage . . .

Doug,
Like the Monte Python joke,
Observer: My dog has no nose
Question: How does it smell?
Observer: Horrible!
I have two K3 transceivers and have attempted to use them on several Field Days with limited joy and unlimited disappointment. I've attempted to use one or the other with 120 Watt solar cells and 100
AH GelCel and/or Lead Acid batteries which had been charged beforehand. As long as there is healthy sunlight and you have a duty cycle of between 10 and 15 percent transmission with 85 to 90
percent monitoring you'll have a functioning station. But, when the sun goes down or you get into a run you'll find yourself out of order.as the battery drops below a nominal 13 VDC.. Operation after twilight, forget it. Again, it's the 13 VDC cutoff. I've used 40 amp boost converters supporting a 13.6 VDC out for a range of input voltages with success, but you can end up frying a battery as the converter struggle to suck 13.6 VDC out of a battery dipping below 10.5 VDC on transmissions. Although I've not tried it, I suspect a Yamaha or Honda 1 KW generator would keep the K3 running, but you're in another category.
Have fun and 73,
John Kountz WO1S

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Bill Frantz

Re: RE; How well does the K3 work with lower power supply voltage . . .

When our club, the West Valley Amateur Radio Association, does
field day, we use many K3 and Flex transceivers. We run them
from 12 volt lead-acid batteries with solar power systems to top
up the batteries. We have had not had any significant problems
in any of SSB, CW, or Digital, although I think the the digital
stations have the heaviest battery drain. We have noticed that
before dawn, when the batteries are getting low, the IMD
increases and we get more QRM from other stations in our
operation. Swapping in a fresh battery always cures the problem.

Note that we run QRP, which helps with avoiding intra-station
QRM and boosts the score.

If I were buying batteries for portable/field operation today, I
would look at the Bioenno LiFePO4 batteries. Good power/weight
and power/size ratios and near full voltage until the end of
their capacity. The down side is they are more expensive the
lead-acid batteries.

73 Bill AE6JV

On 5/28/20 at 8:41 PM, [hidden email] (John Kountz) wrote:

>I have two K3 transceivers and have attempted to use them on
>several Field Days with limited joy and unlimited
>disappointment. I've attempted to use one or the other with
>120 Watt solar cells and 100 AH GelCel and/or Lead Acid
>batteries which had been charged beforehand. As long as there
>is healthy sunlight and you have a duty cycle of between 10 and
>15 percent transmission with 85 to 90
>percent monitoring you'll have a functioning station.

-----------------------------------------------------------------------
Bill Frantz | Ham radio contesting is a | Periwinkle
(408)348-7900 | contact sport. | 150 Rivermead
Rd #235
www.pwpconsult.com | --Ken Widelitz K6LA/VY2TT | Peterborough,
NH 03458

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K7TV

Re: RE; How well does the K3 work with lower power supply voltage . . .

John, I have been using my K3 (sometimes together with my second one) for FD
at 100W for many years with excellent results. The power source is
pre-charged lead acid batteries which we change as needed. Sometimes the
battery in use is assisted by an ancient solar panel that probably doesn't
contribute much. I would roughly say about 3 "full size" batteries are good
to power one K3 and a laptop for the whole contest with no solar. The
batteries have mostly been the flooded type including 12V types and pairs of
6V golf cart ones wired in series (I count the pair as two full size
batteries). My yellow Optima AGM is often used as one of the 3. Starter
batteries are not suitable for the deep discharges we are using. True deep
cycle batteries are best. Marine batteries are ok but not as good for deep
cycling as true deep cycle batteries. It is true that the K3 will work to as
low as about 10.5 V, and we have often abused the batteries by letting them
go down that far. We tried to check voltage often, but... Eventually one
will notice when the radio isn't putting out full power etc. At that point
we disconnect and hook up a new battery or 6 V pair. The low voltage
performance of the K3 is so much better than some other 12V radios. The K3
is specified to require at least 11V. I have a Yaesu radio that is specified
to need at least 11.73V (13.8 V - 15%). One FD we tried an FT-1000MP, which
stopped working when only a small fraction of the battery capacity had been
used up. With decent batteries and doing only one FD per year, the batteries
survive the abuse for several years. Why do I say "abuse" when we use deep
cycle batteries for our deep cycling? It is a bit of a myth in ham circles
that deep cycle lead acid batteries are made to cycle to almost empty. We
get away with it because FD is once a year. The RV industry knows better.
Lots of people live in their RV's year around, and may cycle their batteries
once a day. A good lead acid deep cycle battery (including flooded or AGM
or gel cell) is made to last a few thousand "deep" cycles, but the rule is
your "deep" cycle cannot ever discharge below 50% of battery capacity. I
can't give good statistical data, but with our abusive but rare use I guess
we probably kill a good deep cycle battery in 5 to 10 years. Of course if
you make sure never to go below 11 V, you cn probaly get hundreds of cycles.
Very roughly I would guess we draw about 200 Ah out of the 3 batteries for
the whole contest. Now to your setup with one fully charged 100 Ah batttery
and 120 W solar. Solar panels are spec'ed for lab conditions. In practice I
would guess your panel delivers about 100W at peak and much less at other
times of day. Over the whole day, I would expect to get maybe 500 Wh or
about 40 Ah for the whole day. Then consider that a lead acid battery
self-throttles the charging current when it is close to full. If in your
location the maximum solar radiation occurs near the beginning of the
contest, so the battery is almost full, only a small portiion to the current
offerd by the solar panel can actually go into the battery, and during
receive it cannot go into the rhe radio. So overall you would get much less
than 40 Ah our of the solar for the whole day. The battery has 100 Ah, but
if I remember correctly, that includes charge deliverable after the battery
voltage has dropped a lot, such as below the level where the radio stopped
operating (and you are really asking for battery damage). With a wild guess
(don't ask me to justify these numbers) if you run the K3 like we do, with
your setup you might have only 80 Ah available from the one battery and 20
Ah from the solar panel, for a total of 100 Ah, which is half of the 200 Ah
needed.

73,
Erik K7TV

-----Original Message-----
From: [hidden email] <[hidden email]> On
Behalf Of Bill Frantz
Sent: Wednesday, May 27, 2020 6:13 PM
To: John Kountz <[hidden email]>
Cc: [hidden email]
Subject: Re: [Elecraft] RE; How well does the K3 work with lower power
supply voltage . . .

When our club, the West Valley Amateur Radio Association, does field day, we
use many K3 and Flex transceivers. We run them from 12 volt lead-acid
batteries with solar power systems to top up the batteries. We have had not
had any significant problems in any of SSB, CW, or Digital, although I think
the the digital stations have the heaviest battery drain. We have noticed
that before dawn, when the batteries are getting low, the IMD increases and
we get more QRM from other stations in our operation. Swapping in a fresh
battery always cures the problem.

Note that we run QRP, which helps with avoiding intra-station QRM and boosts
the score.

If I were buying batteries for portable/field operation today, I would look
at the Bioenno LiFePO4 batteries. Good power/weight and power/size ratios
and near full voltage until the end of their capacity. The down side is they
are more expensive the lead-acid batteries.

73 Bill AE6JV

On 5/28/20 at 8:41 PM, [hidden email] (John Kountz) wrote:

>I have two K3 transceivers and have attempted to use them on several
>Field Days with limited joy and unlimited disappointment. I've
>attempted to use one or the other with
>120 Watt solar cells and 100 AH GelCel and/or Lead Acid batteries which
>had been charged beforehand. As long as there is healthy sunlight and
>you have a duty cycle of between 10 and
>15 percent transmission with 85 to 90
>percent monitoring you'll have a functioning station.

-----------------------------------------------------------------------
Bill Frantz | Ham radio contesting is a | Periwinkle
(408)348-7900 | contact sport. | 150 Rivermead
Rd #235
www.pwpconsult.com | --Ken Widelitz K6LA/VY2TT | Peterborough, NH 03458

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Charlie T, K3ICH

Re: RE; How well does the K3 work with lower power supply voltage . . .

When I worked for Vectrol Inc, we designed a new production, battery forming
charger which is needed to make new lead-acid batteries, so I learned a
little about your typical "car" battery when talking to the engineers.
Granted, this was over 40 years ago, so battery technology has obviously
changed a lot since then.
Basically, a pure chemical lead/acid battery cannot supply the yuge starting
current required to crank over a big V8 engine, so antimony is added to the
plates which drastically increases the max current rating.
However, the down side is that this chemical composition battery is
irrevocably damaged if it is allowed to discharge below a certain voltage.
"Deep-Cycle" batteries are simply regular lead/acid batteries without the
added antimony, thus allowing recoverable discharge way below that which
would kill a "car" battery. They won't crank your muscle car over, but a
small electric outboard boat motor is fine.

Since the IMD degrades at low DC supply voltages in our typical 12V powered
finals, if you must use a deep-cycle lead/acid battery, I suggest using one
of those battery booster things that MFJ and probably others sell to keep
the output up.

73, Charlie k3ICH

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Jim Brown-10

Re: RE; How well does the K3 work with lower power supply voltage . . .

On 5/28/2020 5:02 AM, Charlie T wrote:
> Since the IMD degrades at low DC supply voltages in our typical 12V powered
> finals, if you must use a deep-cycle lead/acid battery, I suggest using one
> of those battery booster things that MFJ and probably others sell to keep
> the output up.

Have you tried one? The technology of these devices is usually noisy.

73, Jim K9YC
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Elecraft mailing list

Re: RE; How well does the K3 work with lower power supply voltage . . .

True. I’ve been using one from TGE, the N8XJK booster with analog meters, for years. Initially it generated a lot of crud, but after wrapping the leads with appropriate ferrites, I see and hear ZERO RFI. With this booster I’m able to keep my solar-panel charged AGM battery output set to 14v for the K3/P3 rig.

Jim / W6JHB

> On May 28, 2020, at 10:30 AM, Jim Brown <[hidden email]> wrote:
>>
>
> Have you tried one? The technology of these devices is usually noisy.
>
> 73, Jim K9YC
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Michael Dinkelman

Re: RE; How well does the K3 work with lower power supply voltage . . .

Ditto on that with my mobile

n7wa

On Thu, May 28, 2020 at 10:44 AM James Bennett via Elecraft <
[hidden email]> wrote:

> True. I’ve been using one from TGE, the N8XJK booster with analog meters,
> for years. Initially it generated a lot of crud, but after wrapping the
> leads with appropriate ferrites, I see and hear ZERO RFI. With this booster
> I’m able to keep my solar-panel charged AGM battery output set to 14v for
> the K3/P3 rig.
>
> Jim / W6JHB
>
> > On May 28, 2020, at 10:30 AM, Jim Brown <[hidden email]>
> wrote:
> >>
> >
> > Have you tried one? The technology of these devices is usually noisy.
> >
> > 73, Jim K9YC
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> > Post: mailto:[hidden email]
> >
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> > Message delivered to [hidden email]
>
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ae5ka

Re: RE; How well does the K3 work with lower power supply voltage . . .

In reply to this post by Jim Brown-10

The TGE battery booster I use with my rig on the boat has a BNC for RF
sense to turn on the boost only during transmit, which is the only time is
needed. Works well for me.

73
Chip AE5KA

On Thu, May 28, 2020 at 1:32 PM Jim Brown <[hidden email]> wrote:

> On 5/28/2020 5:02 AM, Charlie T wrote:
> > Since the IMD degrades at low DC supply voltages in our typical 12V
> powered
> > finals, if you must use a deep-cycle lead/acid battery, I suggest using
> one
> > of those battery booster things that MFJ and probably others sell to keep
> > the output up.
>
> Have you tried one? The technology of these devices is usually noisy.
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>

Lynn W. Taylor, WB6UUT-3

Re: RE; How well does the K3 work with lower power supply voltage . . .

Slightly related...

When cars were all 6 volts (I'm not quite old enough to remember when
that was common) the wiring would get a little old, headlights would get
dim, and you could fix that by installing an 8 volt battery and
adjusting the voltage regulator so it'd charge.

I mention this, because I saw that Costco has 8 volt lead-acid batteries
from Interstate Batteries.

An 8 volt and a 6 volt will give you 14 volts, and no boosters necessary.

73 -- Lynn

On 5/29/20 10:05 AM, Chip Stratton wrote:

> The TGE battery booster I use with my rig on the boat has a BNC for RF
> sense to turn on the boost only during transmit, which is the only time is
> needed. Works well for me.
>
> 73
> Chip AE5KA
>
> On Thu, May 28, 2020 at 1:32 PM Jim Brown <[hidden email]> wrote:
>
>> On 5/28/2020 5:02 AM, Charlie T wrote:
>>> Since the IMD degrades at low DC supply voltages in our typical 12V
>> powered
>>> finals, if you must use a deep-cycle lead/acid battery, I suggest using
>> one
>>> of those battery booster things that MFJ and probably others sell to keep
>>> the output up.
>>
>> Have you tried one? The technology of these devices is usually noisy.
>>
>> 73, Jim K9YC
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>> Post: mailto:[hidden email]
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>> Please help support this email list: http://www.qsl.net/donate.html
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>>
> ______________________________________________________________
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>

Phil Kane-2

Re: RE; How well does the K3 work with lower power supply voltage . . .

On 5/30/2020 11:42 AM, Lynn W. Taylor, WB6UUT wrote:

> I mention this, because I saw that Costco has 8 volt lead-acid batteries
> from Interstate Batteries.
>
> An 8 volt and a 6 volt will give you 14 volts, and no boosters necessary.

Ah, but are they the same cell type and are they AGM or gel-cell, the
only type to use in standby communication battery service?

73 de K2ASP - Phil Kane
Elecraft K2/100 s/n 5402

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon
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