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Problems on 40M with 100 watt section

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Rich McCabe

Problems on 40M with 100 watt section

I just noticed that when I am on 40 meters and I am on the 100watt output, I cant transmit. I think something is resetting the MCU because I see "elecraft" flash. It works up to 10 watts without any problems on 40, but as soon as I go above that acts up. All other bands work fine on the 100 watt part.

I dont see anything in troubleshooting but plan to look through the archives.

Any ideas

73,

Rich
kd0zv
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Ron D'Eau Claire-2

RE: Problems on 40M with 100 watt section

Rich, KD0ZV asked:

I just noticed that when I am on 40 meters and I am on the 100watt output, I
cant transmit. I think something is resetting the MCU because I see
"elecraft" flash. It works up to 10 watts without any problems on 40, but as
soon as I go above that acts up. All other bands work fine on the 100 watt
part.

I dont see anything in troubleshooting but plan to look through the
archives.

Any ideas

-------------------------

Frequency sensitive oddities like that are usually the result of RF voltages
getting where they shouldn't.

Try transmitting into a good dummy load and see what happens.

Ron AC7AC

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Rich McCabe

Re: Problems on 40M with 100 watt section

Ron,

This was into a dummy load.

I had it into the KAT100 which was disabled and unplugged. So only the
feedline was left connected though the ATU. Once I removed the KAT100 it
worked.

With the AT removed I did check power output into a dummy load and got the
following

160- 131 watts
75- 118 watts
40- 119 watts
20- 54 watts
17- 55 watts
15 -98 watts
12 - 78 watts
10- 99 watts.

So 20 and 17 are down and 12 slightly??

So I am thinking it must be ATU related and not the 100watt amp section.

Thanks

Rich
kd0zv

----- Original Message -----
From: "Ron D'Eau Claire" <[hidden email]>
To: "'Rich McCabe'" <[hidden email]>; <[hidden email]>
Sent: Saturday, March 18, 2006 4:35 PM
Subject: RE: [Elecraft] Problems on 40M with 100 watt section

Rich, KD0ZV asked:

I just noticed that when I am on 40 meters and I am on the 100watt output, I
cant transmit. I think something is resetting the MCU because I see
"elecraft" flash. It works up to 10 watts without any problems on 40, but as
soon as I go above that acts up. All other bands work fine on the 100 watt
part.

I dont see anything in troubleshooting but plan to look through the
archives.

Any ideas

-------------------------

Frequency sensitive oddities like that are usually the result of RF voltages
getting where they shouldn't.

Try transmitting into a good dummy load and see what happens.

Ron AC7AC

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Ron D'Eau Claire-2

RE: Problems on 40M with 100 watt section

You should see 100 watts on ALL bands so, yes, those are down. Are you
making a minimum of 10 watts out on all bands with the KPA100 disabled?

I don't have a KAT100 myself, so I won't speculate on what might have caused
your original issue beyond the obvious observation that, apparently, it
wasn't really out of the circuit in some way. It may not have been tuning,
but clearly there wasn't a 50-ohm non-reactive path through it either.

Ron AC7AC

-----Original Message-----

Ron,

This was into a dummy load.

I had it into the KAT100 which was disabled and unplugged. So only the
feedline was left connected though the ATU. Once I removed the KAT100 it
worked.

With the AT removed I did check power output into a dummy load and got the
following

160- 131 watts
75- 118 watts
40- 119 watts
20- 54 watts
17- 55 watts
15 -98 watts
12 - 78 watts
10- 99 watts.

So 20 and 17 are down and 12 slightly??

So I am thinking it must be ATU related and not the 100watt amp section.

Thanks

Rich
kd0zv

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Tom Hammond-3

Re: Problems on 40M with 100 watt section

In reply to this post by Rich McCabe

Rich:

>I just noticed that when I am on 40 meters and I am on the 100watt
>output, I cant transmit. I think something is resetting the MCU
>because I see "elecraft" flash. It works up to 10 watts without any
>problems on 40, but as soon as I go above that acts up. All other
>bands work fine on the 100 watt part.
>
>I dont see anything in troubleshooting but plan to look through the archives.

I know this is gonna sound weird, but it's happened before... and
it's load-specific... so you won't see it on all loads...

If you have an o'scope, set the sweep to fairly slow, just fast
enough that the trace is solid across the screen. Set it to DC and
set the trace somewhere near the bottom of the graticule, so you have
essentially all the vertical height the vertical deflection to
2V/div, or whatever will give you almost full vertical deflection
when 12VDC is connected to the probes. Then, hang it across the power
supply line to the rig.

Try transmitting on 40M CW and see if you can see the DC voltage
being pulled VERY LOW just at the instant you start to transmit.
It'll be a very short downward pulse, but it may pull the voltage
down toward 6V or less (I've seen it pulled as low as 3VDC). It will
occur at the instant that the K2 resets, then it'll go right back up.

IF you see this action, and what you've described is 'textbook' for
this occurring, then the KPA100 is going into parasitic oscillation
for just an instant, pulling more current that your PS can provide
(possibly as much as 30A or so), in response to the heavy current
load the PS is going into foldback current limiting and dropping the
voltage to near zero for an instant.

This recently happened with the K2/100 belonging to NN0B (a local to
me). What we found was that the 1mH RFC which is installed back AT
the KPA100 ANT jack had been installed too close to the SO-239 (and a
bit 'into' the cutout for the SO-239. The solution to the problem for
NN0B was for us to physically slide the RFC to the left, as far away
from the cutout slot as possible. That's all we had to do.

Though this is an UNcommon problem it is not an isolated case.

If you don't have access to an o'scope, double-check that the RFC is
physically not 'into' or over any portion of the cutout slot for the
SO-239. If it is, move it as far away from the slot as possible.

Please let me know what you find.

73,

Tom Hammond N0SS

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Rich McCabe

Re: Problems on 40M with 100 watt section

In reply to this post by Rich McCabe

Well as it turns out, my current draw is high. About 2.48 according to the
K2 display. This was at around 8 watts (2:00 position) on the band I
checked. But all bands appear to be around that 2.45-2.5 range.

I checked the finals to make sure there is no short to ground and they did
not. Although there was about 3.5 K resistance on both of them. I assume
this is normal.

I checked the voltage on the finals during xmit and they were 13.4, .6 and
0 as they should be.

Time to search the archives. Any comments would be appreciated.

Rich
kd0zv

----- Original Message -----
From: "Ron D'Eau Claire" <[hidden email]>
To: "'Rich McCabe'" <[hidden email]>
Sent: Saturday, March 18, 2006 5:49 PM
Subject: RE: [Elecraft] Problems on 40M with 100 watt section

Yeah, you definitely have a problem "farther up the line" from the KPA100.
You should see 10 watts, minimum, on all bands from the basic K2. I'd start
by physically removing the KPA100 and testing again.

In addition to feeding power from only the coaxial plug, you can disable
your KPA100 by going into the secondary MENU commands. Also, it does not
kick in until you set the POWER control at 10 watts or above even with the
high-current supply enabled. You can hear a relay click when the KPA100 is
switched in.

But you've determined that the problem is not in the KPA100 itself. Not this
problem at least. First you need to make your K2 produce 10 watts or more on
all bands without it. Ten meters is usually the lowest output band with some
K2's barely making 10 watts, but on other bands, especially 40, most K2's
will produce closer to 15 watts at full power.

Do you hear relays switch when you change bands?? One thing that causes
frequency-specific issues in K2's is if something is amiss in the circuits
that switch in the correct output filter for each band.

Ron AC7AC

-----Original Message-----
From: Rich McCabe [mailto:[hidden email]]
Sent: Saturday, March 18, 2006 3:23 PM
To: Ron D'Eau Claire
Subject: Re: [Elecraft] Problems on 40M with 100 watt section

Ron and Tom,

Tom, yes have a scope and can resport to that if needed. Not an expert with
it, but can make it work :)

Ron, I tried doing the low power thing as you suggested by removing power
from the 100watt unit and using the small Power cord.

160 was 9 watts, 40 was 6 watts. The rest of the band went into HI CUR as I
rotated the dial up to about 1 or 2 oclock and got to 7 or 8 watts. So the
"problem" is further up the line than I thought.

73,

Rich
kd0zv

----- Original Message -----
From: "Ron D'Eau Claire" <[hidden email]>
To: "'Rich McCabe'" <[hidden email]>; <[hidden email]>
Sent: Saturday, March 18, 2006 5:01 PM
Subject: RE: [Elecraft] Problems on 40M with 100 watt section

You should see 100 watts on ALL bands so, yes, those are down. Are you
making a minimum of 10 watts out on all bands with the KPA100 disabled?

I don't have a KAT100 myself, so I won't speculate on what might have caused
your original issue beyond the obvious observation that, apparently, it
wasn't really out of the circuit in some way. It may not have been tuning,
but clearly there wasn't a 50-ohm non-reactive path through it either.

Ron AC7AC

-----Original Message-----

Ron,

This was into a dummy load.

I had it into the KAT100 which was disabled and unplugged. So only the
feedline was left connected though the ATU. Once I removed the KAT100 it
worked.

With the AT removed I did check power output into a dummy load and got the
following

160- 131 watts
75- 118 watts
40- 119 watts
20- 54 watts
17- 55 watts
15 -98 watts
12 - 78 watts
10- 99 watts.

So 20 and 17 are down and 12 slightly??

So I am thinking it must be ATU related and not the 100watt amp section.

Thanks

Rich
kd0zv

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Rich McCabe

Re: Problems on 40M with 100 watt section

Also, just noticed the book says the CAL CUR should be set for 3.5A. Mine
was down to 2.5. I am guessing some software I am testing did this. But now
that I have that bumped up, my current is much higher. Like 3.25.

Rich

----- Original Message -----
From: "Rich McCabe" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, March 18, 2006 7:58 PM
Subject: Re: [Elecraft] Problems on 40M with 100 watt section

> Well as it turns out, my current draw is high. About 2.48 according to the
> K2 display. This was at around 8 watts (2:00 position) on the band I
> checked. But all bands appear to be around that 2.45-2.5 range.
>
> I checked the finals to make sure there is no short to ground and they did
> not. Although there was about 3.5 K resistance on both of them. I assume
> this is normal.
>
> I checked the voltage on the finals during xmit and they were 13.4, .6
> and 0 as they should be.
>
> Time to search the archives. Any comments would be appreciated.
>
> Rich
> kd0zv
>
> ----- Original Message -----
> From: "Ron D'Eau Claire" <[hidden email]>
> To: "'Rich McCabe'" <[hidden email]>
> Sent: Saturday, March 18, 2006 5:49 PM
> Subject: RE: [Elecraft] Problems on 40M with 100 watt section
>
>
> Yeah, you definitely have a problem "farther up the line" from the KPA100.
> You should see 10 watts, minimum, on all bands from the basic K2. I'd
> start
> by physically removing the KPA100 and testing again.
>
> In addition to feeding power from only the coaxial plug, you can disable
> your KPA100 by going into the secondary MENU commands. Also, it does not
> kick in until you set the POWER control at 10 watts or above even with the
> high-current supply enabled. You can hear a relay click when the KPA100 is
> switched in.
>
> But you've determined that the problem is not in the KPA100 itself. Not
> this
> problem at least. First you need to make your K2 produce 10 watts or more
> on
> all bands without it. Ten meters is usually the lowest output band with
> some
> K2's barely making 10 watts, but on other bands, especially 40, most K2's
> will produce closer to 15 watts at full power.
>
> Do you hear relays switch when you change bands?? One thing that causes
> frequency-specific issues in K2's is if something is amiss in the circuits
> that switch in the correct output filter for each band.
>
> Ron AC7AC
>
> -----Original Message-----
> From: Rich McCabe [mailto:[hidden email]]
> Sent: Saturday, March 18, 2006 3:23 PM
> To: Ron D'Eau Claire
> Subject: Re: [Elecraft] Problems on 40M with 100 watt section
>
>
> Ron and Tom,
>
> Tom, yes have a scope and can resport to that if needed. Not an expert
> with
> it, but can make it work :)
>
> Ron, I tried doing the low power thing as you suggested by removing power
> from the 100watt unit and using the small Power cord.
>
> 160 was 9 watts, 40 was 6 watts. The rest of the band went into HI CUR as
> I
> rotated the dial up to about 1 or 2 oclock and got to 7 or 8 watts. So
> the
> "problem" is further up the line than I thought.
>
>
> 73,
>
> Rich
> kd0zv
>
> ----- Original Message -----
> From: "Ron D'Eau Claire" <[hidden email]>
> To: "'Rich McCabe'" <[hidden email]>; <[hidden email]>
> Sent: Saturday, March 18, 2006 5:01 PM
> Subject: RE: [Elecraft] Problems on 40M with 100 watt section
>
>
> You should see 100 watts on ALL bands so, yes, those are down. Are you
> making a minimum of 10 watts out on all bands with the KPA100 disabled?
>
> I don't have a KAT100 myself, so I won't speculate on what might have
> caused
> your original issue beyond the obvious observation that, apparently, it
> wasn't really out of the circuit in some way. It may not have been tuning,
> but clearly there wasn't a 50-ohm non-reactive path through it either.
>
> Ron AC7AC
>
> -----Original Message-----
>
> Ron,
>
> This was into a dummy load.
>
> I had it into the KAT100 which was disabled and unplugged. So only the
> feedline was left connected though the ATU. Once I removed the KAT100 it
> worked.
>
> With the AT removed I did check power output into a dummy load and got the
> following
>
> 160- 131 watts
> 75- 118 watts
> 40- 119 watts
> 20- 54 watts
> 17- 55 watts
> 15 -98 watts
> 12 - 78 watts
> 10- 99 watts.
>
> So 20 and 17 are down and 12 slightly??
>
> So I am thinking it must be ATU related and not the 100watt amp section.
>
> Thanks
>
> Rich
> kd0zv
>
>
>
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

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Vic K2VCO

Re: Problems on 40M with 100 watt section

In reply to this post by Rich McCabe

Rich McCabe wrote:

> Time to search the archives. Any comments would be appreciated.

There is a possible problem with some of the resistors that have been
supplied for R19/R20 having a larger than usual inductance; and also
some capacitors at C80/81 being at the low end of tolerance. This
causes the KPA100 to require much more drive on 20/30/17 meters. You
will see normal current draw at 10 watts, but when you have the
amplifier set for 100 watts the driver current will be higher, and it
won't be possible to get full power out.

Gary Surrency <[hidden email]> has dealt with this problem and can
make suggestions.

Good luck,
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco

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Rich McCabe

Re: Problems on 40M with 100 watt section

Well thanks for everyones comments.

The CAL CUR made a big difference. And after I powered it off and back on,
everything seemed pretty good. Did a partial alignment after that. The radio
draws less with the 100watt running than the 10watt. It is averaging about
2.6 now.

I have excellent power out on 40-160 (115-130 watts). About 95 watts on 20
meters, and is 85 on 10 and 30 but only 75watts on 15 meters. So maybe what
Vic is saying makes sense for my upper bands.

Tom, I am guessing you are right about the parasitic. I still have one
quirk. Goes wild tuning on 40 meters high power. If I run the ATU at low
power it tunes to 1:1 and I can bump the power up to full and its fine !!

73,

Rich
kd0zv

----- Original Message -----
From: "Vic Rosenthal" <[hidden email]>
To: "Elecraft Reflector" <[hidden email]>
Sent: Saturday, March 18, 2006 8:17 PM
Subject: Re: [Elecraft] Problems on 40M with 100 watt section

> Rich McCabe wrote:
>
>> Time to search the archives. Any comments would be appreciated.
>
> There is a possible problem with some of the resistors that have been
> supplied for R19/R20 having a larger than usual inductance; and also
> some capacitors at C80/81 being at the low end of tolerance. This
> causes the KPA100 to require much more drive on 20/30/17 meters. You
> will see normal current draw at 10 watts, but when you have the
> amplifier set for 100 watts the driver current will be higher, and it
> won't be possible to get full power out.
>
> Gary Surrency <[hidden email]> has dealt with this problem and can
> make suggestions.
>
> Good luck,
> --
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

Don Wilhelm-3

RE: Problems on 40M with 100 watt section

In reply to this post by Vic K2VCO

The problem with the resistors Vic mentioned was a short-lived problem that
reared its ugly head last Summer until the Elecraft folks discovered that
the resistor manufacturer had changed the resistor design, so if your KPA100
was not kitted during that timeframe, you should look for another source of
the problem.

73,
Don W3FPR

> -----Original Message-----
>
> Rich McCabe wrote:
>
> > Time to search the archives. Any comments would be appreciated.
>
> There is a possible problem with some of the resistors that have been
> supplied for R19/R20 having a larger than usual inductance; and also
> some capacitors at C80/81 being at the low end of tolerance. This
> causes the KPA100 to require much more drive on 20/30/17 meters. You
> will see normal current draw at 10 watts, but when you have the
> amplifier set for 100 watts the driver current will be higher, and it
> won't be possible to get full power out.
>
> Gary Surrency <[hidden email]> has dealt with this problem and can
> make suggestions.
>
> Good luck,
> --
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco
>
>

Rich McCabe

Re: Problems on 40M with 100 watt section

Nope, its around #4400.

So will have to look elsewhere.

Thanks,

Rich
----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "Elecraft Reflector" <[hidden email]>
Sent: Sunday, March 19, 2006 9:02 AM
Subject: RE: [Elecraft] Problems on 40M with 100 watt section

> The problem with the resistors Vic mentioned was a short-lived problem
> that
> reared its ugly head last Summer until the Elecraft folks discovered that
> the resistor manufacturer had changed the resistor design, so if your
> KPA100
> was not kitted during that timeframe, you should look for another source
> of
> the problem.
>
> 73,
> Don W3FPR
>
>> -----Original Message-----
>>
>> Rich McCabe wrote:
>>
>> > Time to search the archives. Any comments would be appreciated.
>>
>> There is a possible problem with some of the resistors that have been
>> supplied for R19/R20 having a larger than usual inductance; and also
>> some capacitors at C80/81 being at the low end of tolerance. This
>> causes the KPA100 to require much more drive on 20/30/17 meters. You
>> will see normal current draw at 10 watts, but when you have the
>> amplifier set for 100 watts the driver current will be higher, and it
>> won't be possible to get full power out.
>>
>> Gary Surrency <[hidden email]> has dealt with this problem and can
>> make suggestions.
>>
>> Good luck,
>> --
>> 73,
>> Vic, K2VCO
>> Fresno CA
>> http://www.qsl.net/k2vco
>>
>>
>
> _______________________________________________
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>
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>