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K2 kit building problem

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Gordon LaPoint

K2 kit building problem

I'm building a K2 kit and I have a problem. I'm starting the Alignment
and Test, Part III on page 77-78. I have no rf out. I have followed
the rf through the tx chain and have a good signal at (RF board) Q5
collector (800mv P-P) using a 400Mhz scope. I have a signal on Q6 base,
but nothing on the collector. The DC voltage (in TX) at Q6 is 12.0
Collector, 1.8VDC base and 0 on emitter. I don't see anything wrong DC
wise, is it likley that Q6 is bad? What else should I look for? With
the radio off the R at Q6 emitter to ground is 1.8ohms, that looks
normal, so I don't have any current flow in Q6, it looks like.

Thanks,

Gordon - N1MGO

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Don Wilhelm

Re: K2 kit building problem

Gordon,

It is doubtful (but possible) that Q6 is bad. Did it overheat when you
powered up? - if it did, you would most likely have seen a wisp of smoke.

How large is the signal at the base of Q6 when you have 800mV P-P on the
collector of Q5?

The base voltage on Q6 is higher than normal, it should be around 1.1
volts. I would suggest you check all components in the base circuit of
Q6 first.

73,
Don W3FPR

On 3/4/2018 2:26 PM, Gordon LaPoint wrote:
> I'm building a K2 kit and I have a problem. I'm starting the Alignment
> and Test, Part III on page 77-78. I have no rf out. I have followed
> the rf through the tx chain and have a good signal at (RF board) Q5
> collector (800mv P-P) using a 400Mhz scope. I have a signal on Q6 base,
> but nothing on the collector. The DC voltage (in TX) at Q6 is 12.0
> Collector, 1.8VDC base and 0 on emitter. I don't see anything wrong DC
> wise, is it likley that Q6 is bad? What else should I look for? With
> the radio off the R at Q6 emitter to ground is 1.8ohms, that looks
> normal, so I don't have any current flow in Q6, it looks like.
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Gordon LaPoint

Re: K2 kit building problem

Don,
I have about 220mv P-P on the base of Q6. I'm off to check all
the components in the base ckt of Q6, with just DC on the collector.
This is in Tune with the Power out set to 2W.

Thanks,
Gordon - N1MGO

On 3/4/2018 3:10 PM, Don Wilhelm wrote:

> Gordon,
>
> It is doubtful (but possible) that Q6 is bad. Did it overheat when
> you powered up? - if it did, you would most likely have seen a wisp of
> smoke.
>
> How large is the signal at the base of Q6 when you have 800mV P-P on
> the collector of Q5?
>
> The base voltage on Q6 is higher than normal, it should be around 1.1
> volts. I would suggest you check all components in the base circuit
> of Q6 first.
>
> 73,
> Don W3FPR
>
> On 3/4/2018 2:26 PM, Gordon LaPoint wrote:
>> I'm building a K2 kit and I have a problem. I'm starting the
>> Alignment and Test, Part III on page 77-78. I have no rf out. I
>> have followed the rf through the tx chain and have a good signal at
>> (RF board) Q5 collector (800mv P-P) using a 400Mhz scope. I have a
>> signal on Q6 base, but nothing on the collector. The DC voltage (in
>> TX) at Q6 is 12.0 Collector, 1.8VDC base and 0 on emitter. I don't
>> see anything wrong DC wise, is it likley that Q6 is bad? What else
>> should I look for? With the radio off the R at Q6 emitter to ground
>> is 1.8ohms, that looks normal, so I don't have any current flow in
>> Q6, it looks like.

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Gordon LaPoint

Re: K2 kit building problem

In reply to this post by Don Wilhelm

I have checked all the components on the top of the RF board around
Q6. I have not removed the heatsink yet to check C122 and the other
components on the bottom of the board. Resistance checks show that R48
and R50 are correct. The DC voltages on Q6 should show some emitter
voltage when in TX, but the emitter is at 0VDC. The 1.8VDC on the base,
with 12VDC on the collector is trying to tell us something, maybe no
current flow in the transistor?
I have not seen or felt any evidence of overheating on any component
in the radio, at any time.

Gordon - N1MGO

On 3/4/2018 3:10 PM, Don Wilhelm wrote:

Alan - G4GNX

2 meter Linear and ALC with K3

In reply to this post by Gordon LaPoint

I'm about to build a linear amplifier for 2 meters and the design I've
chosen sends a negative voltage to the driving rig's ALC line to inhibit RF
input, whilst the linear goes through a TX sequence.

In view of the way that ALC is used differently with the K3S and KPA500,
does the use of ALC in this way seem feasible for use with the K144XV
transverter?

Has anybody done this?

73,

Alan. G4GNX

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Don Wilhelm

Re: K2 kit building problem

In reply to this post by Gordon LaPoint

Gordon,

That amount of RF is about (with 800mV on the Q5 collector).

I am close to agreeing with you about a bad Q6, but do the checks I
mentioned anyway.

If you do find out Q6 is the culprit -- if this is a kit less than 1
year old, contact support@elecraft and ask for a replacement.
If more than 1 year old (or you were not the original purchaser), it is
not under warranty and you will have to pay for the part - contact the
sales office to do that (make sure you have the part number handy).
They will need payment information. The phone number is 831-763-4211.
The minimum parts order is $5. Get a replacement for Q10 at the same
time, just in case.

73,
Don W3FPR

On 3/4/2018 3:39 PM, Gordon LaPoint wrote:

> Don,
> I have about 220mv P-P on the base of Q6. I'm off to check all
> the components in the base ckt of Q6, with just DC on the collector.
> This is in Tune with the Power out set to 2W.
>
> Thanks,
> Gordon - N1MGO
>
> On 3/4/2018 3:10 PM, Don Wilhelm wrote:
>> Gordon,
>>
>> It is doubtful (but possible) that Q6 is bad. Did it overheat when
>> you powered up? - if it did, you would most likely have seen a wisp of
>> smoke.
>>
>> How large is the signal at the base of Q6 when you have 800mV P-P on
>> the collector of Q5?
>>
>> The base voltage on Q6 is higher than normal, it should be around 1.1
>> volts. I would suggest you check all components in the base circuit
>> of Q6 first.
>>
>> 73,
>> Don W3FPR
>>
>> On 3/4/2018 2:26 PM, Gordon LaPoint wrote:
>>> I'm building a K2 kit and I have a problem. I'm starting the
>>> Alignment and Test, Part III on page 77-78. I have no rf out. I
>>> have followed the rf through the tx chain and have a good signal at
>>> (RF board) Q5 collector (800mv P-P) using a 400Mhz scope. I have a
>>> signal on Q6 base, but nothing on the collector. The DC voltage (in
>>> TX) at Q6 is 12.0 Collector, 1.8VDC base and 0 on emitter. I don't
>>> see anything wrong DC wise, is it likley that Q6 is bad? What else
>>> should I look for? With the radio off the R at Q6 emitter to ground
>>> is 1.8ohms, that looks normal, so I don't have any current flow in
>>> Q6, it looks like.
>
>
> ______________________________________________________________
> 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
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Don Wilhelm

Re: 2 meter Linear and ALC with K3

In reply to this post by Alan - G4GNX

Alan,

I would strongly recommend you use the Transmit Inhibit in the ACC
connector instead (pin 7). See page 21 of the K3S manual and page 66
for the menu (note it is a Tech mode entry).

If you do not have a contact to either ground or +5v in that amplifier,
You may have to devise an intervening circuit to provide either ground
or +5v to ACC pin 7. You should not apply a negative voltage to that pin.

73,
Don W3FPR

On 3/4/2018 4:04 PM, G4GNX wrote:
> I'm about to build a linear amplifier for 2 meters and the design I've
> chosen sends a negative voltage to the driving rig's ALC line to inhibit
> RF input, whilst the linear goes through a TX sequence.
>
> In view of the way that ALC is used differently with the K3S and KPA500,
> does the use of ALC in this way seem feasible for use with the K144XV
> transverter?
>
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Elecraft mailing list

Re: 2 meter Linear and ALC with K3

In reply to this post by Alan - G4GNX

Hi Alan,

I would strongly recommend that you do NOT use ALC for any form of
control signal or drive limiting. For control use the inhibit on the
acc connector and for power output use the K3 pwr control.

Look forward to hearing you on 2m.

73

Peter

G3SMT

On 04/03/2018 21:04, G4GNX wrote:

> I'm about to build a linear amplifier for 2 meters and the design I've
> chosen sends a negative voltage to the driving rig's ALC line to
> inhibit RF input, whilst the linear goes through a TX sequence.
>
> In view of the way that ALC is used differently with the K3S and
> KPA500, does the use of ALC in this way seem feasible for use with the
> K144XV transverter?
>
> Has anybody done this?
>
> 73,
>
> Alan. G4GNX
>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

Alan - G4GNX

Re: 2 meter Linear and ALC with K3

In reply to this post by Don Wilhelm

Thanks Don.

The amp ALC line uses an audio oscillator and diode to generate the negative
voltage, so I can leave it out or add an extra gate for 5V or GND.

73,

Alan. G4GNX

-----Original Message-----
From: Don Wilhelm
Sent: Sunday, March 4, 2018 9:34 PM
To: G4GNX ; [hidden email]
Subject: Re: [Elecraft] 2 meter Linear and ALC with K3

Alan,

I would strongly recommend you use the Transmit Inhibit in the ACC
connector instead (pin 7). See page 21 of the K3S manual and page 66
for the menu (note it is a Tech mode entry).

If you do not have a contact to either ground or +5v in that amplifier,
You may have to devise an intervening circuit to provide either ground
or +5v to ACC pin 7. You should not apply a negative voltage to that pin.

73,
Don W3FPR

On 3/4/2018 4:04 PM, G4GNX wrote:
> I'm about to build a linear amplifier for 2 meters and the design I've
> chosen sends a negative voltage to the driving rig's ALC line to inhibit
> RF input, whilst the linear goes through a TX sequence.
>
> In view of the way that ALC is used differently with the K3S and KPA500,
> does the use of ALC in this way seem feasible for use with the K144XV
> transverter?
>

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Alan - G4GNX

Re: 2 meter Linear and ALC with K3

In reply to this post by Elecraft mailing list

Hi Peter.

I would have used the K3S power control anyway, but I'll modify the
circuitry to accommodate the K3S TX Inhibit.

A QSO should be possible on 2M (even without the linear). My take-off to the
West is good and the slightest lift in conditions seems to get me to West
Wales etc.,

73,

Alan. G4GNX

-----Original Message-----
From: Peter Torry via Elecraft
Sent: Sunday, March 4, 2018 11:22 PM
To: [hidden email]
Subject: Re: [Elecraft] 2 meter Linear and ALC with K3

Hi Alan,

I would strongly recommend that you do NOT use ALC for any form of
control signal or drive limiting. For control use the inhibit on the
acc connector and for power output use the K3 pwr control.

Look forward to hearing you on 2m.

73

Peter

G3SMT

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Gordon LaPoint

Re: K2 kit building problem

In reply to this post by Don Wilhelm

Just got the new Q6 from Elecraft, installed it, and have power out!!!
Now to finish the alignment and get the K2 on the air!
Looks like lots of fun ahead!
Thanks!!
Gordon - N1MGO

On 3/4/2018 4:20 PM, Don Wilhelm wrote:

> Gordon,
>
> That amount of RF is about (with 800mV on the Q5 collector).
>
> I am close to agreeing with you about a bad Q6, but do the checks I
> mentioned anyway.
>
> If you do find out Q6 is the culprit -- if this is a kit less than 1
> year old, contact support@elecraft and ask for a replacement.
> If more than 1 year old (or you were not the original purchaser), it
> is not under warranty and you will have to pay for the part - contact
> the sales office to do that (make sure you have the part number
> handy). They will need payment information. The phone number is
> 831-763-4211.
> The minimum parts order is $5. Get a replacement for Q10 at the same
> time, just in case.
>
> 73,
> Don W3FPR
>
> On 3/4/2018 3:39 PM, Gordon LaPoint wrote:
>> Don,
>> I have about 220mv P-P on the base of Q6. I'm off to check
>> all the components in the base ckt of Q6, with just DC on the
>> collector. This is in Tune with the Power out set to 2W.
>>
>> Thanks,
>> Gordon - N1MGO
>>
>> On 3/4/2018 3:10 PM, Don Wilhelm wrote:
>>> Gordon,
>>>
>>> It is doubtful (but possible) that Q6 is bad. Did it overheat when
>>> you powered up? - if it did, you would most likely have seen a wisp
>>> of smoke.
>>>
>>> How large is the signal at the base of Q6 when you have 800mV P-P on
>>> the collector of Q5?
>>>
>>> The base voltage on Q6 is higher than normal, it should be around
>>> 1.1 volts. I would suggest you check all components in the base
>>> circuit of Q6 first.
>>>
>>> 73,
>>> Don W3FPR
>>> age delivered to [hidden email]