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K3 Main RF Gain problem

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Jim Byers-3

K3 Main RF Gain problem

Hi

Looking for some insight.

K3 # 1189
FW revs 3.68
KAT3
KBPF3 main reciever
KDVR3
KIO3
KPA3
KRX3
KXV3
S-Meter in relative mode.

The problem is with the main RF gain. If I turn down the Main RF gain S
meter goes up as expected, the gain is heard to decrease and seen to
decrease by Spectrogram. So far so good.

When I keep turning the gain down the S meter will increase to S 30 (Rf
knob position 10 o'clock) When the knob position reaches 9:30 the S meter
drops to S6 and the gain comes back up both heard and seen by spectrogram.
Further movement will decrease the gain to zero as heard and seen but the S
meter stays at S6. Increasing the gain the reverse happens. This is true in
all modes.

The sub acts normally as heard and seen by spectrogram and the S-meter acts
as it should.

I suspected the main encoder? I set both the sub and main to the main RF
gain encoder. The main acts the same as before. I expected the sub to act
like the main indicating an encoder problem but the Sub worked exactly as it
should.

During the Smeter calibration the main RF gain acted as it should. Turning
down the gain the s meter goes up, gain goes down as expected with smooth
movement no jumps or lags.

What I have done twice so far without any improvement is
Fresh reload of firmware
Reset to Factory norms
RF Gain Calibration both main and Sub redone
S Meter reset using XG2 main and sub

What should I look at next I really thought it would be the encoder.

Jim
VE3AJ
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n7ws

Re: K3 Main RF Gain problem

Jim,

You say that when you do the S-meter calibration the gain control operates as you expect, but is somehow different otherwise.

First, I hope you mean the rf gain calibration, which isn't calibrating the S-meter but trying to compensate the ill-defined gain v. volts curve of the JFET i-f amplifier.

Nevertheless, after doing this, what are you changing that makes the difference? Is the AGC is the same state, i.e. on or off both ways?

Wes

Hi

Looking for some insight.

K3 # 1189
FW revs 3.68
KAT3
KBPF3 main reciever
KDVR3
KIO3
KPA3
KRX3
KXV3
S-Meter in relative mode.

The problem is with the main RF gain. If I turn down the Main RF gain S
meter goes up as expected, the gain is heard to decrease and seen to
decrease by Spectrogram. So far so good.

When I keep turning the gain down the S meter will increase to S 30 (Rf
knob position 10 o'clock) When the knob position reaches 9:30 the S meter
drops to S6 and the gain comes back up both heard and seen by spectrogram.
Further movement will decrease the gain to zero as heard and seen but the S
meter stays at S6. Increasing the gain the reverse happens. This is true in
all modes.

The sub acts normally as heard and seen by spectrogram and the S-meter acts
as it should.

I suspected the main encoder? I set both the sub and main to the main RF
gain encoder. The main acts the same as before. I expected the sub to act
like the main indicating an encoder problem but the Sub worked exactly as it
should.

During the Smeter calibration the main RF gain acted as it should. Turning
down the gain the s meter goes up, gain goes down as expected with smooth
movement no jumps or lags.

What I have done twice so far without any improvement is
Fresh reload of firmware
Reset to Factory norms
RF Gain Calibration both main and Sub redone
S Meter reset using XG2 main and sub

What should I look at next I really thought it would be the encoder.

Jim
VE3AJ

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Jim Byers-3

Re: K3 Main RF Gain problem

On 09-12-23 0:59 , Wes Stewart wrote:

Wes

RF Gain calibration completed as per manual no problems seen in the
calibration procedure.

If in Config menu >>Smeter OF or other Smeters menus and I move the RF
Gain the Smeter will respond as you would expect.(this is just a curious
sidebar that is probably not useful info)

In normal operation AGC OFF or ON S or F , PRE ON or OFF, ATT IN or OUT,
ALL MODES ALL FITERS I get a gain increase in the main rcvr at the
9:30 position of the the main rf gain.

Since the RF Gain calibration works for the sub reciever and the RF gain
and S meter on the Sub rcvr work correctly I am beginning to suspect
the JFET IF Amp and associated circuits of the main rcvr.

Jim

> Jim,
>
> You say that when you do the S-meter calibration the gain control
> operates as you expect, but is somehow different otherwise.
>
> First, I hope you mean the rf gain calibration, which isn't
> calibrating the S-meter but trying to compensate the ill-defined gain
> v. volts curve of the JFET i-f amplifier.
>
> Nevertheless, after doing this, what are you changing that makes the
> difference? Is the AGC is the same state, i.e. on or off both ways?
>
> Wes
>
>
>
> Hi
>
> Looking for some insight.
>
> K3 # 1189
> FW revs 3.68
> KAT3
> KBPF3 main reciever
> KDVR3
> KIO3
> KPA3
> KRX3
> KXV3
> S-Meter in relative mode.
>
> The problem is with the main RF gain. If I turn down the Main RF
> gain S
> meter goes up as expected, the gain is heard to decrease and seen to
> decrease by Spectrogram. So far so good.
>
> When I keep turning the gain down the S meter will increase to S
> 30 (Rf
> knob position 10 o'clock) When the knob position reaches 9:30 the
> S meter
> drops to S6 and the gain comes back up both heard and seen by
> spectrogram.
> Further movement will decrease the gain to zero as heard and seen
> but the S
> meter stays at S6. Increasing the gain the reverse happens. This
> is true in
> all modes.
>
> The sub acts normally as heard and seen by spectrogram and the
> S-meter acts
> as it should.
>
> I suspected the main encoder? I set both the sub and main to the
> main RF
> gain encoder. The main acts the same as before. I expected the sub
> to act
> like the main indicating an encoder problem but the Sub worked
> exactly as it
> should.
>
> During the Smeter calibration the main RF gain acted as it
> should. Turning
> down the gain the s meter goes up, gain goes down as expected with
> smooth
> movement no jumps or lags.
>
> What I have done twice so far without any improvement is
> Fresh reload of firmware
> Reset to Factory norms
> RF Gain Calibration both main and Sub redone
> S Meter reset using XG2 main and sub
>
>
> What should I look at next I really thought it would be the encoder.
>
> Jim
> VE3AJ
>
>

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Jim Byers-3

Re: K3 Main RF Gain problem

In reply to this post by n7ws

Don Wilhelm-4

Re: K3 Main RF Gain problem

In reply to this post by Jim Byers-3

Jim,

The gain controls are potentiometers, not encoders, so yes, you could
have a bad spot on your RF Gain control such that the resistance has a
"bump" in it near the 9:30 position.
Firmware efforts are not likely to fix it if the pot itself has a
resistance bump.

73,
Don W3FPR

Jim Byers wrote:

>
> The problem is with the main RF gain. If I turn down the Main RF gain S
> meter goes up as expected, the gain is heard to decrease and seen to
> decrease by Spectrogram. So far so good.
>
> When I keep turning the gain down the S meter will increase to S 30 (Rf
> knob position 10 o'clock) When the knob position reaches 9:30 the S meter
> drops to S6 and the gain comes back up both heard and seen by spectrogram.
> Further movement will decrease the gain to zero as heard and seen but the S
> meter stays at S6. Increasing the gain the reverse happens. This is true in
> all modes.
>
> The sub acts normally as heard and seen by spectrogram and the S-meter acts
> as it should.
>
>

n7ws

Re: K3 Main RF Gain problem

In reply to this post by Jim Byers-3

In working with Lyle on earlier versions of the rf calibration I saw some of this same action. In some cases, the s-meter wouldn't even reach FS at min RFG.

You might try backing off to factory defaults and starting over, making sure you have the latest utility.

On 09-12-23 0:59 , Wes Stewart wrote:

Wes

RF Gain calibration completed as per manual no problems seen in the
calibration procedure.

If in Config menu >>Smeter OF or other Smeters menus and I move
the RF Gain the Smeter will respond as you would expect.(this is just a
curious sidebar that is probably not useful info)

In normal operation AGC OFF or ON S or F , PRE ON or OFF, ATT IN or
OUT, ALL MODES ALL FITERS I get a gain increase in the main rcvr at
the 9:30 position of the the main rf gain.

Since the RF Gain calibration works for the sub reciever and the RF
gain and S meter on the Sub rcvr work correctly I am beginning to
suspect the JFET IF Amp and associated circuits of the main rcvr.

Jim

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Jim Byers-3

Re: K3 Main RF Gain problem

In reply to this post by Don Wilhelm-4

On 09-12-23 8:09 , Don Wilhelm wrote:
Don,

When the sub is using the main gain potentiometer I thought that the sub
should also be effected but it is not.

Jim

> Jim,
>
> The gain controls are potentiometers, not encoders, so yes, you could
> have a bad spot on your RF Gain control such that the resistance has a
> "bump" in it near the 9:30 position.
> Firmware efforts are not likely to fix it if the pot itself has a
> resistance bump.
>
> 73,
> Don W3FPR
>
> Jim Byers wrote:
>>
>> The problem is with the main RF gain. If I turn down the Main RF gain S
>> meter goes up as expected, the gain is heard to decrease and seen to
>> decrease by Spectrogram. So far so good.
>>
>> When I keep turning the gain down the S meter will increase to S 30 (Rf
>> knob position 10 o'clock) When the knob position reaches 9:30 the S
>> meter
>> drops to S6 and the gain comes back up both heard and seen by
>> spectrogram.
>> Further movement will decrease the gain to zero as heard and seen but
>> the S
>> meter stays at S6. Increasing the gain the reverse happens. This is
>> true in
>> all modes.
>>
>> The sub acts normally as heard and seen by spectrogram and the
>> S-meter acts
>> as it should.
>>
>

Jim Byers-3

Re: K3 Main RF Gain problem

In reply to this post by n7ws

Wes,

The s-meter indications are really no more than a nuisance. But the RF
gain behavior is something I need to address.
I am using the latest utility and firmware.
Will start from scratch again (third time) see if anything changes

Jim

On 09-12-23 9:54 , Wes Stewart wrote:

> In working with Lyle on earlier versions of the rf calibration I saw
> some of this same action. In some cases, the s-meter wouldn't even
> reach FS at min RFG.
>
> You might try backing off to factory defaults and starting over,
> making sure you have the latest utility.
>
> On 09-12-23 0:59 , Wes Stewart wrote:
>
> Wes
>
> RF Gain calibration completed as per manual no problems seen in
> the calibration procedure.
>
> If in Config menu >>Smeter OF or other Smeters menus and I move
> the RF Gain the Smeter will respond as you would expect.(this is
> just a curious sidebar that is probably not useful info)
>
> In normal operation AGC OFF or ON S or F , PRE ON or OFF, ATT IN
> or OUT, ALL MODES ALL FITERS I get a gain increase in the main
> rcvr at the 9:30 position of the the main rf gain.
>
> Since the RF Gain calibration works for the sub reciever and the
> RF gain and S meter on the Sub rcvr work correctly I am beginning
> to suspect the JFET IF Amp and associated circuits of the main rcvr.
>
> Jim
>
>>
>

n7ws

Re: K3 Main RF Gain problem

--- On Wed, 12/23/09, Jim Byers <[hidden email]> wrote:
The s-meter indications are really no more than a nuisance. But the RF
gain behavior is something I need to address.

I agree. The meter is just a proxy for what is happening to the gain, which is a real problem.

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Joe Planisky

Re: K3 Main RF Gain problem

In reply to this post by Jim Byers-3

Hi Jim,

Are you by any chance running the RF gain calibration with the Linux
or Mac version of the K3 Utility? An earlier release of the Mac
version and the current release of the Linux version seem to have some
problems with RF gain calibration. Everything seems to go right
during and immediately after the calibration procedure, but once you
turn the rig off and back on, you get reduced gain and the s-meter
doesn't go full scale at min RF gain (as Wes described.) That's not
exactly the symptom you described, but I don't know what else might be
messed up in this case.

Anyway, my point is that if you're using a Mac or Linux machine to do
the RF gain calibration, you might want to try it with a Windows
machine to see if it fixes your problem.

73
--
Joe KB8AP

On Dec 23, 2009, at 7:19 AM, Jim Byers wrote:

> Wes,
>
> The s-meter indications are really no more than a nuisance. But the RF
> gain behavior is something I need to address.
> I am using the latest utility and firmware.
> Will start from scratch again (third time) see if anything changes
>
> Jim
>
>
>
> On 09-12-23 9:54 , Wes Stewart wrote:
>> In working with Lyle on earlier versions of the rf calibration I saw
>> some of this same action. In some cases, the s-meter wouldn't even
>> reach FS at min RFG.

wayne burdick

Re: K3 Main RF Gain problem

Administrator

In reply to this post by n7ws

Lyle and I will look into this issue when he gets back from vacation.

73,
Wayne
N6KR
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G3TCT

Re: K3 Main RF Gain problem

In reply to this post by Jim Byers-3

Jim
I've had exactly your problem (and sorry for rather late response).
I'm using Windows (so it's not that) and it's not the encoder/pot, it's the
rf gain calibration. I've posted on this before and there's been a change
to the rf gain setup since f/w 3.27. Wes has also mentioned that fets have a
somewhat uncontrolled gain characteristic.

I redid the rf gain calibration but using factory defaults rather than an
external sig gen and that cured it. Only trouble now is the S meter
over-reads above S9+10 by up to 20dB. But I can live with that.

It's interesting (spooky?) that you have #1189 and I have #1198.....

Graham

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Jim Byers-3

Re: K3 Main RF Gain problem

In reply to this post by wayne burdick

To All

Your input was helpful and appreciated, Thanks.

Problem solved.
It was the Rf Gain Calibration that caused the problem.

Initial run was done using a MacPro running Snow Leporad problem may
have started here. ( will check into that tomorrow)

Second and Third runs done on a MacPro using Boot Camp and Win 7 64bit
Home Premium
Went Straight to the option of using the XG 2 as the source. (a mistake
on my part should have known to start from a known state) Problem still
there after both runs.

Fourth run done on a MacPro using Boot Camp and Win 7 64bit Home Premium
Picked first option of writing factory values only.
Problem Gone.

Fifth run done on a MacPro using Boot Camp and Win 7 64bit Home Premium
Used XG 2 as source Problem Gone

Short version_ Stay with Factory defaults_ unless you have a good reason
to make a change.

Jim
VE3AJ

On 09-12-23 11:33, Wayne Burdick wrote:
> Lyle and I will look into this issue when he gets back from vacation.
>
> 73,
> Wayne
> N6KR
>

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K5WA

Re: K3 Main RF Gain problem

In reply to this post by Jim Byers-3

Jim,

I have the same issue and I noticed it after I installed the DVR, however
I'm not sure the two events are connected. I sent a note to K3Support and
they said this is a firmware issue they are fixing. I have not loaded 3.68
yet to see if the fix is in there, but it really isn't a big deal for
me.although, I will be glad when it works properly again. ;-)

Bob K5WA

Jim Byers wrote:

>

> The problem is with the main RF gain. If I turn down the Main RF gain S

> meter goes up as expected, the gain is heard to decrease and seen to

> decrease by Spectrogram. So far so good.

>

> When I keep turning the gain down the S meter will increase to S 30 (Rf

> knob position 10 o'clock) When the knob position reaches 9:30 the S meter

> drops to S6 and the gain comes back up both heard and seen by spectrogram.

> Further movement will decrease the gain to zero as heard and seen but the
S

> meter stays at S6. Increasing the gain the reverse happens. This is true
in

> all modes.

>

> The sub acts normally as heard and seen by spectrogram and the S-meter
acts

> as it should.

>

>

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