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K1 80/40 tx problem

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Igor Lána

K1 80/40 tx problem

Hello friends,
I built a kit K1 80/40. Everything was no problem. All values of resistors
and DC voltages were OK. But in chapter 9, part "Band 1 Allignment",
transistor Q7 has been melted (2W at 80 m band).
I changed it and after that I measured current - 0.1 W on 3.6 MHz current
is 1.1A! On 7 MHz, is slightly better - 0.1W is 0.4 A but the 2W is 1.3 A.
After several attempts to find mistake, I tried to use the "Signal
Transmitter tracing" with DRV-ground jumper. Instead of RF Probe I used the
old oscilloscop in multimetr mode. I performed the measurements to the point
15. All values looked like okay, but from the point 10, I watched the
unstability.
I switched oscilloscop to the measurement curve mode. And on OSC it is not
pure sine wave. The point of MIX has been very vibrant. ATTN is clean. I do
not know if the problem is on 6-7 intputs U8 or output 4.
Please, see videos of measuring on youtube.
ociloscop 150ns time raster: http://www.youtube.com/watch?v=fYTOw9DWfKI
ociloscop 50ns time raster: http://www.youtube.com/watch?v=9mUunLQdBuU
ociloscop-multimeter: http://www.youtube.com/watch?v=oFaKCssXsA
In every video first part is on ATTN, second on OSC, and the third on MIX.

Please, do you have some recommendations how or where to find the error?
Can Xtal X6 defective?

Thanks
73 Igor OK1TGI

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Don Wilhelm-4

Re: K1 80/40 tx problem

Igor,

The waveshapes are normal. They will not be anything like a sine wave
coming out of a mixer, but the fundemental RF voltage is still present,
so the waveform will be cleaned up by the bandpass filters and the PA
Low Pass Filter.

Since you have excessive current draw, the first place to look is the
Low Pass Filter on the 2 band board. Are the capacitors correct? Are
the number of turns on the toroids correct? Count the turns carefully,
counting each turn that goes through the center of the core - a straight
wire through a toroid is one turn, a full wrap around the core is two
turns. Failure to realize that fact is a common builder error.

73,
Don W3FPR

On 9/26/2010 12:06 PM, Igor Lána wrote:

> Hello friends,
> I built a kit K1 80/40. Everything was no problem. All values of resistors
> and DC voltages were OK. But in chapter 9, part "Band 1 Allignment",
> transistor Q7 has been melted (2W at 80 m band).
> I changed it and after that I measured current - 0.1 W on 3.6 MHz current
> is 1.1A! On 7 MHz, is slightly better - 0.1W is 0.4 A but the 2W is 1.3 A.
> After several attempts to find mistake, I tried to use the "Signal
> Transmitter tracing" with DRV-ground jumper. Instead of RF Probe I used the
> old oscilloscop in multimetr mode. I performed the measurements to the point
> 15. All values looked like okay, but from the point 10, I watched the
> unstability.
> I switched oscilloscop to the measurement curve mode. And on OSC it is not
> pure sine wave. The point of MIX has been very vibrant. ATTN is clean. I do
> not know if the problem is on 6-7 intputs U8 or output 4.
> Please, see videos of measuring on youtube.
> ociloscop 150ns time raster: http://www.youtube.com/watch?v=fYTOw9DWfKI
> ociloscop 50ns time raster: http://www.youtube.com/watch?v=9mUunLQdBuU
> ociloscop-multimeter: http://www.youtube.com/watch?v=oFaKCssXsA
> In every video first part is on ATTN, second on OSC, and the third on MIX.
>
> Please, do you have some recommendations how or where to find the error?
> Can Xtal X6 defective?
>
> Thanks
> 73 Igor OK1TGI
>
> ______________________________________________________________
> 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
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

Igor Lána

Re: K1 80/40 tx problem

Hello Don,
thank you for advice.

I check L9 and L10 again a it looks like good
(http://ok1tgi.nagano.cz/obrazky/K1/L9_L10.jpg) - 28 turns.
I check all condensators on FB for 80m band and everything is OK.

I made new measuring.
I removed out the DRV-ground jumper and checked waveshapes on DRV and PA
pads.
Power supply 13,8V/3.5A, output power 0.1W, dummy load 15W Nagoya 0-500MHz.
Oscilloscop Createc SC-03, 9MHz
Current was 0,45A on 40m, 0,98A on 80m.

DRV 7MHz (150ns, 1V): http://ok1tgi.nagano.cz/obrazky/K1/DRV_7MHz.jpg
DRV 3.5MHz (150ns, 2V): http://ok1tgi.nagano.cz/obrazky/K1/DRV_3MHz.jpg
PA 7MHz (150ns, 5V): http://ok1tgi.nagano.cz/obrazky/K1/PA_7MHz.jpg
PA 3.5MHz (150ns, 20V): http://ok1tgi.nagano.cz/obrazky/K1/PA_3MHz.jpg

Yes, there isn't little bit nice sinusoid. But bigger surprise was measuring
in multimetr mode.

DRV 7MHz = 650mV rms: http://ok1tgi.nagano.cz/obrazky/K1/DRV_7MHz_mm.jpg
PA 7MHz = 3.6V : http://ok1tgi.nagano.cz/obrazky/K1/PA_7MHz_mm.jpg
DRV 3.5MHz = 1V (?!): http://ok1tgi.nagano.cz/obrazky/K1/DRV_3MHz_mm.jpg
PA 3.5MHz = 14.9V (!!): http://ok1tgi.nagano.cz/obrazky/K1/PA_3MHz_mm.jpg

This is strange values, isn't it ?

But the biggest mystery - see lowest line on PA 3.5 MHz multimetr PA
measuring - there is 7.177 MHz !!!
I also made short checking with better oscilloscop (200MHz) at work on
friday. And it showed me the same problem. But I didn't have dummy load and
I thought that is the reason.

Is the PA over-drived ? Does it work in class C correctly ?

I checked "POWER" signal on pin 6, connector J1
RX 2.2 V for both bands. TX 3.5MHz = 2.94V DC, 7Mhz = 3.17V DC.

L1-L8 are adjusted for the best RX. Attemps in TX are complicated. On 80m I
can't setup higer otput that 0.5 W because current is too high. On 40m I can
adjust maximum 1W output with 2.0 "menu level".

Now I don't have any ideas.

Igor OK1TGI

----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "Igor Lána" <[hidden email]>
Cc: <[hidden email]>
Sent: Sunday, September 26, 2010 7:33 PM
Subject: Re: [Elecraft] K1 80/40 tx problem

> Igor,
>
> The waveshapes are normal. They will not be anything like a sine wave
> coming out of a mixer, but the fundemental RF voltage is still present, so
> the waveform will be cleaned up by the bandpass filters and the PA Low
> Pass Filter.
>
> Since you have excessive current draw, the first place to look is the Low
> Pass Filter on the 2 band board. Are the capacitors correct? Are the
> number of turns on the toroids correct? Count the turns carefully,
> counting each turn that goes through the center of the core - a straight
> wire through a toroid is one turn, a full wrap around the core is two
> turns. Failure to realize that fact is a common builder error.
>
> 73,
> Don W3FPR
>
> On 9/26/2010 12:06 PM, Igor Lána wrote:
>> Hello friends,
>> I built a kit K1 80/40. Everything was no problem. All values of
>> resistors
>> and DC voltages were OK. But in chapter 9, part "Band 1 Allignment",
>> transistor Q7 has been melted (2W at 80 m band).
>> I changed it and after that I measured current - 0.1 W on 3.6 MHz
>> current
>> is 1.1A! On 7 MHz, is slightly better - 0.1W is 0.4 A but the 2W is 1.3
>> A.
>> After several attempts to find mistake, I tried to use the "Signal
>> Transmitter tracing" with DRV-ground jumper. Instead of RF Probe I used
>> the
>> old oscilloscop in multimetr mode. I performed the measurements to the
>> point
>> 15. All values looked like okay, but from the point 10, I watched the
>> unstability.
>> I switched oscilloscop to the measurement curve mode. And on OSC it is
>> not
>> pure sine wave. The point of MIX has been very vibrant. ATTN is clean. I
>> do
>> not know if the problem is on 6-7 intputs U8 or output 4.
>> Please, see videos of measuring on youtube.
>> ociloscop 150ns time raster: http://www.youtube.com/watch?v=fYTOw9DWfKI
>> ociloscop 50ns time raster: http://www.youtube.com/watch?v=9mUunLQdBuU
>> ociloscop-multimeter: http://www.youtube.com/watch?v=oFaKCssXsA
>> In every video first part is on ATTN, second on OSC, and the third on
>> MIX.
>>
>> Please, do you have some recommendations how or where to find the error?
>> Can Xtal X6 defective?
>>
>> Thanks
>> 73 Igor OK1TGI
>>
>> ______________________________________________________________
>> 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
>>

Don Wilhelm-4

Re: K1 80/40 tx problem

Igor,

Given the high RF voltage at the PA on 3.5 MHz, you may have an open Low
Pass Filter - check for continuity on the 2 band board from P3 pin 1 to
P3 pin 8 for both bands. If one or both are open, you have a poorly
tinned toroid lead.

If that is not the problem, you may want to get [hidden email]
involved.

73,
Don W3FPR

On 9/27/2010 6:39 AM, Igor Lána wrote:

> Hello Don,
> thank you for advice.
>
> I check L9 and L10 again a it looks like good
> (http://ok1tgi.nagano.cz/obrazky/K1/L9_L10.jpg) - 28 turns.
> I check all condensators on FB for 80m band and everything is OK.
>
> I made new measuring.
> I removed out the DRV-ground jumper and checked waveshapes on DRV and PA
> pads.
> Power supply 13,8V/3.5A, output power 0.1W, dummy load 15W Nagoya 0-500MHz.
> Oscilloscop Createc SC-03, 9MHz
> Current was 0,45A on 40m, 0,98A on 80m.
>
> DRV 7MHz (150ns, 1V): http://ok1tgi.nagano.cz/obrazky/K1/DRV_7MHz.jpg
> DRV 3.5MHz (150ns, 2V): http://ok1tgi.nagano.cz/obrazky/K1/DRV_3MHz.jpg
> PA 7MHz (150ns, 5V): http://ok1tgi.nagano.cz/obrazky/K1/PA_7MHz.jpg
> PA 3.5MHz (150ns, 20V): http://ok1tgi.nagano.cz/obrazky/K1/PA_3MHz.jpg
>
> Yes, there isn't little bit nice sinusoid. But bigger surprise was measuring
> in multimetr mode.
>
> DRV 7MHz = 650mV rms: http://ok1tgi.nagano.cz/obrazky/K1/DRV_7MHz_mm.jpg
> PA 7MHz = 3.6V : http://ok1tgi.nagano.cz/obrazky/K1/PA_7MHz_mm.jpg
> DRV 3.5MHz = 1V (?!): http://ok1tgi.nagano.cz/obrazky/K1/DRV_3MHz_mm.jpg
> PA 3.5MHz = 14.9V (!!): http://ok1tgi.nagano.cz/obrazky/K1/PA_3MHz_mm.jpg
>
> This is strange values, isn't it ?
>
> But the biggest mystery - see lowest line on PA 3.5 MHz multimetr PA
> measuring - there is 7.177 MHz !!!
> I also made short checking with better oscilloscop (200MHz) at work on
> friday. And it showed me the same problem. But I didn't have dummy load and
> I thought that is the reason.
>
> Is the PA over-drived ? Does it work in class C correctly ?
>
> I checked "POWER" signal on pin 6, connector J1
> RX 2.2 V for both bands. TX 3.5MHz = 2.94V DC, 7Mhz = 3.17V DC.
>
> L1-L8 are adjusted for the best RX. Attemps in TX are complicated. On 80m I
> can't setup higer otput that 0.5 W because current is too high. On 40m I can
> adjust maximum 1W output with 2.0 "menu level".
>
> Now I don't have any ideas.
>
> Igor OK1TGI
>
> ----- Original Message -----
> From: "Don Wilhelm"<[hidden email]>
> To: "Igor Lána"<[hidden email]>
> Cc:<[hidden email]>
> Sent: Sunday, September 26, 2010 7:33 PM
> Subject: Re: [Elecraft] K1 80/40 tx problem
>
>
>> Igor,
>>
>> The waveshapes are normal. They will not be anything like a sine wave
>> coming out of a mixer, but the fundemental RF voltage is still present, so
>> the waveform will be cleaned up by the bandpass filters and the PA Low
>> Pass Filter.
>>
>> Since you have excessive current draw, the first place to look is the Low
>> Pass Filter on the 2 band board. Are the capacitors correct? Are the
>> number of turns on the toroids correct? Count the turns carefully,
>> counting each turn that goes through the center of the core - a straight
>> wire through a toroid is one turn, a full wrap around the core is two
>> turns. Failure to realize that fact is a common builder error.
>>
>> 73,
>> Don W3FPR
>>
>> On 9/26/2010 12:06 PM, Igor Lána wrote:
>>> Hello friends,
>>> I built a kit K1 80/40. Everything was no problem. All values of
>>> resistors
>>> and DC voltages were OK. But in chapter 9, part "Band 1 Allignment",
>>> transistor Q7 has been melted (2W at 80 m band).
>>> I changed it and after that I measured current - 0.1 W on 3.6 MHz
>>> current
>>> is 1.1A! On 7 MHz, is slightly better - 0.1W is 0.4 A but the 2W is 1.3
>>> A.
>>> After several attempts to find mistake, I tried to use the "Signal
>>> Transmitter tracing" with DRV-ground jumper. Instead of RF Probe I used
>>> the
>>> old oscilloscop in multimetr mode. I performed the measurements to the
>>> point
>>> 15. All values looked like okay, but from the point 10, I watched the
>>> unstability.
>>> I switched oscilloscop to the measurement curve mode. And on OSC it is
>>> not
>>> pure sine wave. The point of MIX has been very vibrant. ATTN is clean. I
>>> do
>>> not know if the problem is on 6-7 intputs U8 or output 4.
>>> Please, see videos of measuring on youtube.
>>> ociloscop 150ns time raster: http://www.youtube.com/watch?v=fYTOw9DWfKI
>>> ociloscop 50ns time raster: http://www.youtube.com/watch?v=9mUunLQdBuU
>>> ociloscop-multimeter: http://www.youtube.com/watch?v=oFaKCssXsA
>>> In every video first part is on ATTN, second on OSC, and the third on
>>> MIX.
>>>
>>> Please, do you have some recommendations how or where to find the error?
>>> Can Xtal X6 defective?
>>>
>>> Thanks
>>> 73 Igor OK1TGI
>>>
>>> ______________________________________________________________
>>> 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
> 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
>