Re: [Elecraft] K2 RF Gain Control

[KD0Q]

Thanks Don & Keith

I'm going to replace both pots and do the wiring mod.  Also saw in the
archives where the earphone jack can be an issue and will replace that
too.

73, Glenn KD0Q

On Thu, Aug 15, 2019 at 4:03 PM Don Wilhelm  wrote:

> All the pots in the K2 are sealed - no way for either dust or cleaning
> fluids to get into the pot workings.
>
> To substitute a different variable resistor, one would have to remove
> the pot from the board - may as well just change it.  Order a new one
> from Elecraft.
>
> 73,
> Don W3FPR
>
> On 8/15/2019 4:26 PM, Keith wrote:
> > The first thing you should check is dust on the control variable
> > resistor. Using a different variable resistor will give you a quick
> answer.
> >
> > 73, Keith
> >
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to k...@traer.net
>
>
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] K2 RF Gain Control

[Don Wilhelm]

All the pots in the K2 are sealed - no way for either dust or cleaning 
fluids to get into the pot workings.


To substitute a different variable resistor, one would have to remove 
the pot from the board - may as well just change it.  Order a new one 
from Elecraft.


73,
Don W3FPR

On 8/15/2019 4:26 PM, Keith wrote:
The first thing you should check is dust on the control variable 
resistor. Using a different variable resistor will give you a quick answer.


73, Keith


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] K2 RF Gain Control

[Keith]

The first thing you should check is dust on the control variable 
resistor. Using a different variable resistor will give you a quick answer.


73, Keith

KM6WIZ


On 8/15/19 12:49 PM, KD0Q wrote:

I have a new to me K2 SN in the 1200's that appears to have a flaky RF Gain
control.  The lightest of touch on the knob triggers what I think is AGC.
The receiver goes silent for a few seconds, longer with slow AGC.  Is it
the pot or is there something else I should be looking at?

If I need to replace the RF Gain pot, what other updates should I do while
I've got the panel off?

Thanks.

73, Glenn KD0Q
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to n6...@att.net


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] K2 RF Gain Control

[Don Wilhelm]

Glenn,

It does sound like the RF Gain pot has become scratchy - replace it, 
don't even bother with temporary fixes like cleaning stuff.


With that serial number, replace both the RF Gain pot and the AF Gain 
pot.  While you have the front panel board removed from the metalwork, I 
would recommend that you do the entire Alternate AF Gain Wiring Mod.  It 
involves all three boards, but no parts - only trace cuts and added wire.


73,
Don W3FPR

On 8/15/2019 3:49 PM, KD0Q wrote:

I have a new to me K2 SN in the 1200's that appears to have a flaky RF Gain
control.  The lightest of touch on the knob triggers what I think is AGC.
The receiver goes silent for a few seconds, longer with slow AGC.  Is it
the pot or is there something else I should be looking at?

If I need to replace the RF Gain pot, what other updates should I do while
I've got the panel off?


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] K2 RF gain control triggers sloooow agc action

[v...@vicsfloridavilla]

Hi Keith,

Well blow me down !  I twiddled the rf pot a couple of dozen times and guess 
what ? It's OK now !  Must have been a bit of dirt in the pot. I might get a 
spare on my next order to Elecraft.so that's 1 x K3 with 100w pa , 1x 
1500watt PA module , 1x rf pot ...

Many thanks. Am copying this to the reflector for reference purposes in case 
someone else has the same problem .

73 de Vic GW4JUN

Message: 4
From: "Darwin, Keith" 
Subject: Re: [Elecraft] K2 RF gain control triggers slw agc action


Is it a noisy pot?  If you spin the RF gain knob back & forth a bunch of
times, then try your experiment again, does it give the same results? 

- Keith N1AS -



-- 
I am using the free version of SPAMfighter.
We are a community of 6 million users fighting spam.
SPAMfighter has removed 212 of my spam emails to date.
Get the free SPAMfighter here: http://www.spamfighter.com/len

The Professional version does not have this message
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Re: [Elecraft] K2 RF gain control triggers sloooow agc action ?

[Darwin, Keith]

Is it a noisy pot?  If you spin the RF gain knob back & forth a bunch of
times, then try your experiment again, does it give the same results? 

- Keith N1AS -
- K3 711 -

-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of
v...@vicsfloridavilla
Sent: Tuesday, June 30, 2009 12:08 PM
To: elecraft@mailman.qth.net
Subject: [Elecraft] K2 RF gain control triggers slw agc action ?

Hi Folks,

Recently I have noticed that my K2 has developed a strange effect.

If I move (even very slightly) the rf gain control the audio silences
and the S meter shows full deflection. After about three seconds or so
the receiver recovers and the s meter returns to normal.  This happens
wherever teh rf gain control is positioned about it's axis.

My K2 is no 1926 and currently has the original af gain circuit. I do
have the Elecraft mod to cure the "noise" problem but it is not yet
fitted.

Any suggestions ?

73 de Vic GW4JUN



--
I am using the free version of SPAMfighter.
We are a community of 6 million users fighting spam.
SPAMfighter has removed 212 of my spam emails to date.
Get the free SPAMfighter here: http://www.spamfighter.com/len

The Professional version does not have this message
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

RE: [Elecraft] K2 RF Gain Control question

[Rod]

How interesting. My #1126 K2 does exactly as you described Todd. Although I
rarely change the rf control level, I've always wondered why my K2 behaved
this way. It'll be interesting to see what kind of comments your question
brings. 

73,

Rod
K5BGB
Licensed June 1955

-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Todd Gahagan
Sent: Sunday, February 18, 2007 10:18 AM
To: Elecraft Reflector
Subject: [Elecraft] K2 RF Gain Control question

I just noticed that whenever I touch my RF gain control knob for adjustment
the S meter jumps completely to the right and VERY slowly drops to whatever
level of RF gain I have set.  It takes several seconds for the receiver to
come back to the point where it can receive again.  I have used other K2's
and this has not been the case.  Can someone else tell me if they see this
happening.  I probably haven't explained this very well but would be glad to
explain this more if needed.

Thanks, WA7U
Todd
___
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

___
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Re: [Elecraft] K2 RF Gain Control question

[Todd Gahagan]

The lube is a good place to start Ron.  Thanks.  I have noticed that just 
touching the RF knob causes this to happen so you are probably on to 
something here.  I don't have a lube other than tri-flow but will look for 
something like what you mentioned.  Todd 


___
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft


Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Re: [Elecraft] K2 RF Gain Control question

[Ken Kopp]

Spraying the chemical onto/into a "Q-tip" and 
then squeezing it out by pressing the cotton

against the upward-pointing shaft will avoid the
splattering.  


73! Ken Kopp - K0PP (K2 #5665)
[EMAIL PROTECTED]
or
[EMAIL PROTECTED]


___
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft


Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Re: [Elecraft] K2 RF Gain Control question

[Todd Gahagan]

Thanks Tom,

I suspect the gain pot is defective.  I will check soldering also.  I'll get 
an RF gain pot on the way and try swapping it out also.


Todd 


___
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft


Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

RE: [Elecraft] K2 RF Gain Control question

[Ron D'Eau Claire]

Todd, that sounds like a "noisy" pot in which the wiper isn't making good
contact with the resistive element inside. When you touch it, the circuit
opens briefly, which is the same as turning the RF Gain all the way to
minimum. That will cause the S-meter to read full scale. The delay returning
to normal should be the AGC decay rate. If you tap AGC to switch to FAST, it
should recover much more quickly. 

One fix is to put a few drops of a control lubricant on the control shaft
with the rig standing front panel upward so the lubricant will run into the
pot. Turn it a number of times to work it down into the resistive element. I
use Caig DeOxit for that. It comes in a small squeeze bottle with a hollow
needle applicator. Recommend you avoid any sprays. They get stuff all over
the place. If a spray is all you have, recommend you spray onto a small
screwdriver shaft or length of wire it to collect drops of liquid on the
wire or screwdriver shaft. Work away from the rig with a towel behind the
sprayer to catch the overspray. Then position the wet wire or screwdriver
shaft so the drops run down onto the pot shaft and into the pot itself. 

If it's a stubborn case, you may need to replace the pot. 

Ron AC7AC

-Original Message-

I just noticed that whenever I touch my RF gain control knob for adjustment
the S meter jumps completely to the right and VERY slowly drops to whatever
level of RF gain I have set.  It takes several seconds for the receiver to
come back to the point where it can receive again.  I have used other K2's
and this has not been the case.  Can someone else tell me if they see this
happening.  I probably haven't explained this very well but would be glad to
explain this more if needed.

Thanks, WA7U
Todd

___
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Re: [Elecraft] K2 RF Gain control

[Stewart Baker]

On Thu, 20 Jan 2005 10:11:38 -0500, Dale Boresz wrote:
> Hello Bob,
>
> I have noticed on my K2, that if I adjust the AGC threshold such that
> the background noise level *truly* doesn't change when turning the AGC
> on and off, then the RF gain control when turned completely ccw, does
> not sufficiently reduce the level of very strong stations.
>
> I have to adjust the AGC threshold such that there is at least some AGC
> action, and then the RF gain control does actually reduce volume level
> when turned ccw.
>
> When trying to copy weak signals, I prefer to operate with the AGC off,
> the AF Gain advanced, and I use the RF Gain control to control the
> signal level. This seems to give me the best signal-to-noise ratio. So,
> in order to have enough range of adjustment with the RF Gain control, I
> adjust the AGC threshold until the RF Gain, when adjusted fully ccw,
> sufficiently attenuates the largest signals. That seems to be the best
> compromise.
>
> I make no claim that this is the 'correct' way to adjust the AGC
> threshold. It's just a method that I've found works best for the way I
> prefer to operate. What's nice about the K2, is that we *can* perform
> these kinds of optimizations.
>
> 73, Dale WA8SRA
>
I find the K2 RF Gain (IF gain) control very ineffective with either the AGC on 
or off. I tend to use the RF ATT - better from the point of overload, IMD's etc.
The RF gain control on my FT1000MP can reduce S9+60 signals to zero.

73
Stewart G3RXQ

___
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Re: [Elecraft] K2 RF Gain control

[Dale Boresz]

Hello Bob,

I have noticed on my K2, that if I adjust the AGC threshold such that 
the background noise level *truly* doesn't change when turning the AGC 
on and off, then the RF gain control when turned completely ccw, does 
not sufficiently reduce the level of very strong stations.


I have to adjust the AGC threshold such that there is at least some AGC 
action, and then the RF gain control does actually reduce volume level 
when turned ccw.


When trying to copy weak signals, I prefer to operate with the AGC off, 
the AF Gain advanced, and I use the RF Gain control to control the 
signal level. This seems to give me the best signal-to-noise ratio. So, 
in order to have enough range of adjustment with the RF Gain control, I 
adjust the AGC threshold until the RF Gain, when adjusted fully ccw, 
sufficiently attenuates the largest signals. That seems to be the best 
compromise.


I make no claim that this is the 'correct' way to adjust the AGC 
threshold. It's just a method that I've found works best for the way I 
prefer to operate. What's nice about the K2, is that we *can* perform 
these kinds of optimizations.


73, Dale WA8SRA


Robert Greenwalt wrote:


... I recently noticed that the RF
gain control doesn't change signal levels coming out of the speaker.
The control has been left at max until I played with it recently, and I
was surprised to notice that its only function seems to be changing the
number of illuminated LEDs in the S-meter.  I tried it with various AF
gain control levels and with the AGC both active and turned off - no
difference.  ... 
Bob Greenwalt
K6VZT 

 



___
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft


Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Re: [Elecraft] K2 RF Gain control

[G3VVT]

Hi Bob,
 
Sounds normal and very much like my K2.
The RF gain in the K2 is really an IF gain with the front end RF gain  set at 
a constant level and only affected by switching in the preamp or the  
attenuator. I have an old JRC receiver where the RF gain works the  same as the 
K2 in 
that the effect as the RF gain is turned down is the  lower level signals 
fall below the threshold as the S meter rises and are  effectively suppressed. 
This is a useful effect to give arm chair copy of  stronger signals and 
minimises the amount of noise between syllables.
 
Bob, G3VVT
___
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Re: [Elecraft] K2 RF Gain control

[W3FPR - Don Wilhelm]

Bob,

If the RF gain control changes the number of LEDs on the S-meter reading, it 
is functioning properly.


Now, with that said, yes you MAY have the AGC Threshold set incorrectly.  As 
long as AGC action is present, the audio level should be more or less 
constant - that is its proper function.  When the AGC threshold is set too 
low (higher voltage on U2 pin 5, the K2 will produce more AGC voltage it 
should and will de-sensitize the receiver even with no signal.  The proper 
fine adjust setting for the AGC Threshold is just at the level where the K2 
internal noise does not activate the AGC - you can test that condition by 
switching from AGC on to AGC off on a quiet band or with no antenna 
connected.  If the noise rises with AGC off, the AGC Threshold is set too 
high.  I commonly find the correct setting will yield a voltage at U2 pin 5 
of 3.6 to 3.8 volts.


If you have a high noise level at your QTH, the noise alone may be 
activating the AGC and cause the conditions you describe.


73,
Don W3FPR

- Original Message - 


I have a K2 with almost all of the add-ons (everything but DSP - and the
100 watt amplifier has just been added) and all elecraft mods that has
functioned well for over a year - but I recently noticed that the RF
gain control doesn't change signal levels coming out of the speaker.
The control has been left at max until I played with it recently, and I
was surprised to notice that its only function seems to be changing the
number of illuminated LEDs in the S-meter.  I tried it with various AF
gain control levels and with the AGC both active and turned off - no
difference.  Before I get into massive troubleshooting, is it possible
over time and changing various internal settings several times I have
misadjusted something?  I get signals on the bands.

Bob Greenwalt
K6VZT



___
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft


Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Re: [Elecraft] K2 RF Gain control

[n2fq]

FYI,
Robert I just replace the RF control when I did the SMD Indicator mod.
The RF control started to act like a squelch whenever I touched it or bumped
it when turning the dial. Had to leave it in it's wide position. After 
replacing

it, things are back to normal.

take care

--

73
Fernando N2FQ/NNNØJYM 
San Jose, CA



___
Elecraft mailing list
Post to: Elecraft@mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft


Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com