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SSB TX signal mystery SOLVED !!!

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Marinos

SSB TX signal mystery SOLVED !!!

First let me thank Don (w3fpr) and Garry (ab7my) for their excellent support
and guidance for the resolution of this problem.
As posted earlier, I had a disappearance of my Tx SSB signal after
installing the adaptor to the K2 with normal RX and normal CW Tx. Had spent
some hours looking at the different boards without finding the culprit and
finally started chasing the SSB signal with the oscilloscope to see where it
was blocked.
That signal was going fine all the way past the crystal filter, exiting the
C5 cap after the T1 transformer but then could not be found at the cathode
of D14 !!!!
That's very strange indeed I thought, since the C5 is supposed to be
connected to the cathode of D14 ?!?!?
And here came the realization that I had done the STUPID mistake of
installing the D14 cathode 90deg away from its normal pad, to a similar pad
reserved for the R10.....Of course, at a later construction step I had
realized that one of the R10 pads was occupied, but I thought it was normal
and had soldered it there anyway (another stupidity).

Anyway, I can go on and on about how this should never had happened, but it
only took a 90deg rotation of this diode without even removing it from the
board to fix this.
Now I have full SSB output and are 1/2 way done with my K2 100W amplifier
board before I have everything up and running.
Already built the NB, AF filter and successfully passed the first alignment
test of the 100W board....

The above story is a good example of what happens when you stay up too many
hours building your K2. But as you know, when you start you can not easily
contain yourself from continuing building. It is addictive !!!

73 to all,
Marinos, ki4gin

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Cyberia

RE: SSB TX signal mystery SOLVED !!!

I made that exact same mistake!!! When it came time to install R10, however,
I realized the through-hole should not be occupied, and I discovered my
mistake.

I have not gotten so far along as to test my SSB adapter yet, and I am glad
I found this before I got that far.

It's strange that we both made exactly the same mistake. Perhaps the
markings there could be improved or a note in the assembly manual...

De N3WZ - Jim

> -----Original Message-----
> From: [hidden email] [mailto:elecraft-
> [hidden email]] On Behalf Of Marinos Markomanolakis, M.D.
> Sent: Tuesday, December 28, 2004 7:50 PM
> To: [hidden email]
> Subject: [Elecraft] SSB TX signal mystery SOLVED !!!
>
> First let me thank Don (w3fpr) and Garry (ab7my) for their excellent
> support
> and guidance for the resolution of this problem.
> As posted earlier, I had a disappearance of my Tx SSB signal after
> installing the adaptor to the K2 with normal RX and normal CW Tx. Had
> spent
> some hours looking at the different boards without finding the culprit and
> finally started chasing the SSB signal with the oscilloscope to see where
> it
> was blocked.
> That signal was going fine all the way past the crystal filter, exiting
> the
> C5 cap after the T1 transformer but then could not be found at the cathode
> of D14 !!!!
> That's very strange indeed I thought, since the C5 is supposed to be
> connected to the cathode of D14 ?!?!?
> And here came the realization that I had done the STUPID mistake of
> installing the D14 cathode 90deg away from its normal pad, to a similar
> pad
> reserved for the R10.....Of course, at a later construction step I had
> realized that one of the R10 pads was occupied, but I thought it was
> normal
> and had soldered it there anyway (another stupidity).
>
> Anyway, I can go on and on about how this should never had happened, but
> it
> only took a 90deg rotation of this diode without even removing it from the
> board to fix this.
> Now I have full SSB output and are 1/2 way done with my K2 100W amplifier
> board before I have everything up and running.
> Already built the NB, AF filter and successfully passed the first
> alignment
> test of the 100W board....
>
> The above story is a good example of what happens when you stay up too
> many
> hours building your K2. But as you know, when you start you can not easily
> contain yourself from continuing building. It is addictive !!!
>
> 73 to all,
> Marinos, ki4gin
>
>
> _______________________________________________
> Elecraft mailing list
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> You must be a subscriber to post to the list.
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>
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> Elecraft web page: http://www.elecraft.com

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Ken G3WCS

Re: SSB TX signal mystery SOLVED !!!

Cyberia wrote:
> I made that exact same mistake!!! When it came time to install R10, however,
> I realized the through-hole should not be occupied, and I discovered my
> mistake.

Make that three!

I just completed my KSB2 yesterday and very nearly made the same mistake
with D14. I had placed it in the PCB and was just about to solder it
when I thought it didn't look quite right. I quickly turned it through
90 degrees and soldered it correctly.

I think the thing that throws you is the fact that everything on the
right hand site of the board up til this point is symmetrical, from top
to bottom. Therefore I had subconsciously thought that D14 was a mirror
image of D4 on the lower part of the board which is mounted 90 degrees
differently.

It might be worth a quick one liner in the KSB2 manual to warn against
this pitfall. My KSB2 is now fitted to my K2 (#4489) and I had my first
SSB QSO on 40m's this morning. Reports were good. Touch wood, an XV144,
XV50 and now my K2 has gone together perfectly without a hitch. Built
the KNB2 today and will be fitting tomorrow.

Just one more small observation with regard to mic pinouts. I am using
an Icom HM-12 electret condenser mic with my K2. Table 2 on P18 of the
KSB2 manual seems to indicate that the 10K resistor to feed the DC to
the mic should go from the 5V side of the mic config block to pin 2 of
the mic. This is not correct, as according to the circuit of the HM-12
in the Icom IC-735 manual, there is no connection to pin 2 in the mic
itself. The DC voltage is fed up the audio cable (pin 1) and blocked
from the audio path inside the mic by a capacitor and routed to the
mic's internal pre-amp. Connected the 10k from 5v to pin 1 and away it
went with stacks of audio.

Happy holidays and New Year.

Ken.
--

Ken G3WCS <[hidden email]>
IO83rh : Cheshire : NW England
(+44) (0)1606 892677 (home)
(+44) (0)7733 400950 (mobile & sms)
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Cyberia

RE: SSB TX signal mystery SOLVED !!!

Is your KSB2 manual revision E (July 20, 2004)??

If so, then you need to carefully examine the notes at the top of the table
for the ICOM mikes. The note at the top of the table says NOT to connect pin
2 unless the MIC is pre-amplified. It says to connect AF (pin1) to 5V
through a 10K resistor for HM-12 (your MIC) or 820 Ohms for HM-7.

De N3WZ - Jim.

> -----Original Message-----
> From: [hidden email] [mailto:elecraft-
> [hidden email]] On Behalf Of Ken G3WCS
> Sent: Wednesday, December 29, 2004 4:21 PM
> To: [hidden email]
> Subject: Re: [Elecraft] SSB TX signal mystery SOLVED !!!
>
> Cyberia wrote:
> > I made that exact same mistake!!! When it came time to install R10,
> however,
> > I realized the through-hole should not be occupied, and I discovered my
> > mistake.
>
> Make that three!
>
> I just completed my KSB2 yesterday and very nearly made the same mistake
> with D14. I had placed it in the PCB and was just about to solder it
> when I thought it didn't look quite right. I quickly turned it through
> 90 degrees and soldered it correctly.
>
> I think the thing that throws you is the fact that everything on the
> right hand site of the board up til this point is symmetrical, from top
> to bottom. Therefore I had subconsciously thought that D14 was a mirror
> image of D4 on the lower part of the board which is mounted 90 degrees
> differently.
>
> It might be worth a quick one liner in the KSB2 manual to warn against
> this pitfall. My KSB2 is now fitted to my K2 (#4489) and I had my first
> SSB QSO on 40m's this morning. Reports were good. Touch wood, an XV144,
> XV50 and now my K2 has gone together perfectly without a hitch. Built
> the KNB2 today and will be fitting tomorrow.
>
> Just one more small observation with regard to mic pinouts. I am using
> an Icom HM-12 electret condenser mic with my K2. Table 2 on P18 of the
> KSB2 manual seems to indicate that the 10K resistor to feed the DC to
> the mic should go from the 5V side of the mic config block to pin 2 of
> the mic. This is not correct, as according to the circuit of the HM-12
> in the Icom IC-735 manual, there is no connection to pin 2 in the mic
> itself. The DC voltage is fed up the audio cable (pin 1) and blocked
> from the audio path inside the mic by a capacitor and routed to the
> mic's internal pre-amp. Connected the 10k from 5v to pin 1 and away it
> went with stacks of audio.
>
> Happy holidays and New Year.
>
>
> Ken.
> --
>
> Ken G3WCS <[hidden email]>
> IO83rh : Cheshire : NW England
> (+44) (0)1606 892677 (home)
> (+44) (0)7733 400950 (mobile & sms)
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
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>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

Ken G3WCS

Re: SSB TX signal mystery SOLVED !!!

Cyberia wrote:
> Is your KSB2 manual revision E (July 20, 2004)??
>
> If so, then you need to carefully examine the notes at the top of the table
> for the ICOM mikes. The note at the top of the table says NOT to connect pin
> 2 unless the MIC is pre-amplified. It says to connect AF (pin1) to 5V
> through a 10K resistor for HM-12 (your MIC) or 820 Ohms for HM-7.

Yes it is Rev E and it says, to quote "Do not connect pin 2 unless mic
has internal preamp".

My mic does have an internal preamp and therefore according to the table
pin 2 would appear be the logical choice.

OTOH a dynamic moving coil mic, such as the early Kenwood models which
have the mic insert directly connected between pin 1 and earth do not
have an internal preamp and do not require the 5v being presented via a
resistor.

What I think the table is referring to is that some later mics have the
preamp voltage fed up a dedicated wire connected to pin 2. In my older
mic the signal cable (pin 1) doubles as signal and preamp voltage carrier.

73,

Ken.

--

Ken G3WCS <[hidden email]>
IO83rh : Cheshire : NW England
(+44) (0)1606 892677 (home)
(+44) (0)7733 400950 (mobile & sms)
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