Well this post is 10 years old, but I am having the exact same problem. I
have checked with a magnifying glass for any solder bridges or poor solder
joints. Everything looks fine. I'd appreciate any further troubleshooting
ideas.
73,
Jeremy
VA3ZTF
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Ok, I received the new diodes today and have installed them into the KAT100.
Running the tests in CAL mode has the LED indicators on the KAT100 matching
what the display on the K2 reads, as well as matching the W2 watt meter. Is
there anything else I should be looking at before starting to put
Thanks Don. The KPA 100 is still disconnected. I have the base K2 with KAT2
connected to the KAT100 in the EC2 chassis. This normally has the KPA100 on
top, but was removed as suggested to perform the troubleshooting.
I don't have an extra dummy load at this time, but I am going to see if I
Parts are on order. I'll update once I have the diodes swapped. Thanks for
the help thus far.
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Ok, so I've removed the KPA100 completely, and disconnected the KAT2 serial
and RF connections. I connected my W2 watt meter on the output of ANT2 of
the KAT100, and the LOAD side of the sensor to a 50 ohm dummy load. The
readings and indications I got are as follows:
160M1.00:1 No LED
Ok, redid the tests in CAL mode with the following results:
160M 1.03:1 No LED indication on KAT100. K2 showed 1.0:1 Hi Current
warning
80M 1.03:1 No LED indication on KAT100. K2 showed 1.0:1 Hi Current
warning
60M 1.02:1 No LED indication on KAT100. K2 showed 1.0:1 Hi Current
The diodes I was looking at were 1N5711, but they were either 70V 15mA
(http://www.digikey.ca/scripts/DkSearch/dksus.dll?DetailitemSeq=176360177uq=635730153536694158)
or 70V 33mA
(http://www.digikey.ca/product-search/en/discrete-semiconductor-products/diodes-rectifiers-single/1376383?k=1n5711).
I
What are the specs for the diodes? I'm seeing 70V 15mA as the common size.
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After many months of flawless operation, my KAT100 is starting to have
trouble tuning up, particularly on 40 and 80M. It even has trouble tuning
up a 50 ohm dummy load on these bands.
My normal setup is a 10W K2 with a KAT2, connected on the ANT 1 port to the
AUX RF port of the KAT100 (mounted
I'm only running 10W through it.
I've just gone through the complete instruction manual to ensure I haven't
missed anything. Everything checks out. I've just finished the SWR Bridge
Null test and am down to 0.018VDC.
Jeremy
VA3ZTF
Don Wilhelm-4 wrote
Jeremy,
How much power are you
Correction, 0.018 was at 5W. 10W still gives 0.036VDC
Jeremy
JeremyJones wrote
I'm only running 10W through it.
I've just gone through the complete instruction manual to ensure I haven't
missed anything. Everything checks out. I've just finished the SWR
Bridge Null test and am down
Checked my dummy load with an MFJ-259 and it is 50 ohms resistive, no
capacitive. Rechecked all soldering with a lighted magnifying glass and
cleaned up a couple of joints. Rewound T1 just to be sure it wasn't shorted
in the windings.
Still the same results of 0.035VDC on pin 3 of U5.
Jeremy
I was only able to get U5 pin3 down to 0.03VDC during the SWR Bridge Null
test. Is that low enough? The manual says 0 volts or close to it.
Jeremy
VA3ZTF
Don Wilhelm-4 wrote
Jeremy,
You did not mention it, so I have to ask - when connected as you
describe, did you first obtain a good
I just reread Dons post, and he says less than 10mV, so I guess I have some
trouble shooting to do with that first,
Jeremy
VA3ZTF
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practical, one may not
be able to adjust the capacitor in fine enough increments to achieve
that goal.
73,
Don W3FPR
On 2/28/2014 4:32 PM, JeremyJones wrote:
I just reread Dons post, and he says less than 10mV, so I guess I have
some
trouble shooting to do with that first,
Jeremy
I have just finished my KAT100, and am having an issue during the Power
Calibration of R3 and R4. I am using a K2 with KAT2. I have a cable
running from the Ant 1 jack of the KAT2 to the Ant 1 jack of the KAT100.
The KAT100 RF In jack is connected to the Transmitter jack of the power
sensor of
Q7, Q8, Q11 and Q13 are all now replaced, and everything seems to be working
normally again. Thanks everyone for all the help.
73,
Jeremy
VA3ZTF
JeremyJones wrote
Yes that was an Alkaline battery. That makes me feel better about
installing the new finals once they arrive. In the mean time
I don't know how much over 0.64 volts is bad, but I am getting 0.656.
I didn't realize that a web reply was cutting off what I was replying to. I
always hit the reply button and assumed it included the original text.
Jeremy
Don Wilhelm-4 wrote
Jeremy,
A power reading of 0.1, 0.2 or 0.3
you for adding a bit of the prior post that you are responding to
- it helps a lot.
73,
Don W3FPR
On 2/18/2014 4:46 PM, JeremyJones wrote:
I don't know how much over 0.64 volts is bad, but I am getting 0.656.
I didn't realize that a web reply was cutting off what I was replying to.
I
voltage down a bit.
73,
Don W3FPR
On 2/18/2014 6:58 PM, JeremyJones wrote:
A new AA battery right from the package is giving me 1.615V on the fluke
meter. This is a newer K2 (#7405). I had some issues when building it
which caused me to go through a couple of sets of PA finals before I had
With the tuner disconnected, I'm still getting 600mV at the base of Q8 while
doing a tune. The display on the radio shows power of 0.3.
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I'm still getting 600mV and LowP during the tune, so it looks like I'll be
replacing Q11 and Q13 as well.
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There is no indication on the cheap meter for an out of scale reading.
I've borrowed a Fluke meter from work, and after watching the capacitors
charge up, the resistance reading is 2.7k ohm. This is will all of the
resistors still connected as above. I'll reconnect them one by one and
check the
So after reassembling everything minus Q7/8, resistance from ground to
collector pad for Q7/8 starts at 600k ohm then gradually drops down to 54k
ohm before reseting and spiking back up to 600k and dropping again. I
believe this would be a capacitor charging up and then biasing a transistor?
Yes it is a digital multimeter, but I only paid about $10 for it.
What resistance should I be seeing. I have noticed some drastic variations
as I change the scale on my meter. The 200 ohm scale gives a reading of 91
ohms
2000 ohms scale reads 1500
20K scale reads 3.7
200k scale reads 10.7
What
With Q7/Q8 removed, the resistance from the Collector solder pad to ground on
both is 70 ohms.
Doing a Tune with Q7/Q8 removed results in 1.0V on the Base pads and a Low
P on the display. I do have the KAT2 installed, just in case this makes a
difference. This was done into a dummy load.
The
Lifting one end of R45 still showed 70 ohms. Lifting one end of RFC4
increased to 87 ohms. I left the leg of R45 disconnected when taking this
measurement, and I want to confirm whether I should leave the components
disconnected as I go through, or reconnect them before moving on to the
next.
I have lifted R45, RFC4, R74, R82 and R97, with only a slight increase from
70 ohms to 87 ohms after lifting RFC4. I'll continue troubleshooting
tomorrow by removing any capacitors connected to 12V.
I also want to confirm that I should be doing these resistance checks with
no power applied.
So my K2, which has been running great for almost a year, no longer powers
on. I had left it powered on and connected via the serial cable to a
computer so that I could do PSK-31 contacts remotely while I was away from
home. Unfortunately I never got the chance, and upon my return home, my K2
Q7 and Q8 both read 12.3 ohms from collector to ground.
The symptoms definitely resemble blown finals, as I experienced the same
thing when I was building the kit, including the over current tripping the
resettable fuse. I just didn't expect that from a receive only condition.
Jeremy
VA3ZTF
Upon opening the radio to follow some of the trouble shooting advice given,
the fault was easy to spot. The wire on the L2 torroid had broken. A quick
rewind and reinstall, and everything is working fine now.
Thanks for all the help,
Jeremy
VA3ZTF
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So I was out on Sunday trying to make some contacts for the Rookie Roundup,
as well as generally learning the ins and outs of my K2, and I found that
when I try to tune on 160M I get the Low P error. I've tried using a dummy
load, 20M long wire dipole, and buddypole setup for both vertical and
Don,
I suspected something might be wrong with the watt meter, as it was borrowed
from work and had not been used in a while.
I was able to listen to quite a few signals last night, however I wasn't
able to make any contacts. I brought my radio into work and tested it on a
Rhode and Schwartz
So, I have learned another lesson on paying attention to details. Seems the
analog watt meter I was using is only rated as low as 20mhz, and the digital
Rhode and Schwartz actually had a 200Mhz sensor on it. No wonder the
readings were bad.
I did go back to the analog meter on 15M, 12M, and
Looks like a bad coax was indeed causing the high current issue. I've
resolved that, but I'm still show no power out on the external watt meter,
while the internal is reading 2.4.
Jeremy
VA3ZTF
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The watt meter has a 5, 15, 50, 100W ranges, and I was using the 15 and 5 to
try and get measurements. Carrying on with calibration using the internal
meter yielded the expected results. I may actually be able get this on the
air tonight!
Thanks for the help,
Jeremy
VA3ZTF
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I'm trying to complete the stage 3 transmitter alignment on my K2 and have
run into a bit of a snag. The 40M check looks good according to the built
in power meter, however with an external watt meter connected to a dummy
load, I am getting less than 1W on the with the K2 set at 2W, and about 2W
Hi Don,
The capacitors all look good, and I found one issue with a toroid and
corrected it, but the issue remains. T4 is wound with proper number of
turns, but wires do overlap some instead of being stacked neatly. Not sure
if this could cause an issue or not. T4 is also standing off the board
After some more trouble shooting with Gary from Elecraft, he decided to send
me a new U4. After installing it, all tests and alignment for step 2 went
off without any issues at all.
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So Gary from Elecraft gave me some things to check today. Heres where I am
at for the moment.
T5 is back to 15 turns of red. This brings the frequency close to spec @
TP1.
Pulled C72 and measured its value at 273pF.
U6 has 4V @ pin5 and pin1 goes from 7.5 to 0V when doing the PLL range test.
T5
So Cal PLL is still not working.
The 5V from U4 pin13 makes it all the way to U6 pin 6, but is blocked by C94
on the other branch.
Still only 0.020V at R30.
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So this morning I started rechecking everything. I've found that the 5V on
U4 pin 5 is intermittent. Not in a way that would indicate a loose or poor
connection, but either that it is there, or it isn't (mostly isn't) when
powering up the unit. U7 always has the 5V on pin2. I checked the
Looking over the board I did find that I had U8 C45 connected to pin7 instead
of pin6. That has been corrected.
U6 pin 24 to U4 pin5 is less than 1 ohm, however U6 pin24 to U7 pin2 is 300k
ohm. I don't see any damage on the board.
I also noticed going back to the beginning for the resistance
Rechecked the resistance, and indeed there is 300k from U6 pin 24 to U7 pin2.
Looking at the schematic in the manual, it shows U6 pin24 connected to U7
pin5 and U8 pin11. At this point I do have less than 1 ohm.
The schematic shows U6 pin23 connected to U7 pin2 which is reading less than
1 ohm.
No problem Don, you've been a huge help.
So I went back to the beginning and did all resistance checks in the manual
up to this point and everything is good.
PLL range test @ 7100.00khz gives me 12099.13 high and 12086.33 low.
VCO @ 4000.10 gives me 7840.33
I do still have some bad voltages
So I really thing that U4 is faulty. It's putting out 5.029V on pin13 when
that should only be 4V. All the components surrounding it seem to have the
correct voltages according to the manual. I think I'll replace that and see
how things look after.
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I'm in the process of building a K2 and am having trouble at the Alignment
and Test part 2. I've gone through at ton of previous posts here an have
been talking with Gary at Elecraft but no luck so far. The main issues are
C22 only has adjustment less than 1khz (12085-12086) @ TP3, and R30 which
Hi Don,
I set C22 to midway.
PLL @ TP3 is 12099.12 - 12086.32.
T5 is a yellow core, wound with 15 turns red and 4 green. I had to bring it
down to 15 turns as recommended by Gary to get 8253.86khz @ TP1 when tuned
to 4000.10 for the VCO test. It was around 7694.39 with 16 turns.
L30 is the
Don,
Checked D19 is n in the secondary menu. L30 does change frequency.
Soldering iron is set to 775F. I'm using one of those illuminated workbench
magnifying lamps to examine my work. Even still I reflowed the solder on
all joints to be sure. U6 circuit components are the correct values and
U4 pin13 = 5.029V
U6 pin6 = 5.026V
U6 pin7 = 0.020V
L30 with 1 red lead removed = 0.5ohm
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C62 is correct, and the path is intact. Reflowed the solder on all
connections just to be sure.
U4 readings are as follows
Pin1 = 0.111
Pin2 = 0.339
Pin3 = 0.006
Pin4 = 2.363
Pin5 = 4.99
Pin6 = 4.99
Pin7 = 4.99
Pin8 = 4.99
Pin9 = 0.001
Pin10 = 0.001
Pin11 = 0.000
Pin12 = 0.000
Pin13 = 5.029
So I started tracing back and checking joints and reflowing solder. I now
have 0.760 @ pin8, 0.000 @ pin 13, and 0.00 @ pin 15.
R30 is now showing 8.04V, but 40M is reading in the 13000khz range, with L30
able to adjust frequency but not voltage.
I'm thinking I may need to add back in the turn
Thanks Don,
I'll rewind T5 and see where that gets me.
U4 pins 1 and 2 are still low (no change), and U7 pin2 and U4 pin5 are
equal. Do you still suspect there may be an issue with U4?
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Rewound T5 and now I seem to be back at square 1.
U4 pin13 is high again @5.029V when tuned to 7100khz.
R30 is back to 0.02V
40M is at 11351.25
L30 still changes frequency.
The VCO test at 4000.10 results in 7794.5 @ TP1.
U7 pin2 and U4 pin5 are both 4.99V.
I think I'll call it quits for tonight
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