K3 #1193 - CHIRP

[Bruce Meier-2]

I think this problem is one for Aptos, but as they are off for a well
deserved Thanksgiving break, I thought I would share my wows with the
reflector.

 

Tonight I decided to spend a few hours tonight operating in CQWW-CW.  Much
to my dismay, part of the exchange received on my second QSO was informing
me that I had a VERY bad chirp.   I quickly shut down the amp and switched
to the dummy load and turned on my other K3 to monitor my signal.   WOW - K3
# 1193 has one terrible chirp indeed.   My other K3,  #1062 sounds fine.

 

Here is what I have done so far to try to isolate the issue.

 

One comment - Before we went out this morning I was running EU on 20mtrs and
had no complaints about my signal.  Also worked some US stations and I would
hope they would have said something. So, I think what ever the issue is, it
happened when I turned it on tonight.

 

> Swapped power supplies - (no change)

> Turned down the power from 60w (feeding the amp) to 10 watts - (no change)

> Turned on the display to check the voltage - 13.5 key down at 60 watts -
NO PROBLEM

> Took the KPA3 out of the circuit via Config / Bypass  and only ran 5 watts
- (no change)

> Tried all the other bands.

                - 3.5mhz has a raspy sound to the note (ripple)

                - 14.0mhz has the chirp

                - ALL OTHER bands are fine.

> For drill I also did a cpu reset (Norm - Pwr ON) - (no change)

> Went back to an older version of microcode - 3.44 (no change)

> Reloaded 3.63 - (no change)

> Did a transmitter gain calibration - (no change)

> Performed Synthesizer re-calibration on both main and sub RX - (no change)

> Tried SPLIT on 14.0 to see if there was any difference when transmitting
on VFO B.

                - "YES" - VFO B has a much more pronounced chirp than VFO A

> Tried SPLIT on the other bands - only 3.5 mhz has an issue and it is the
same HASH as when VFO A is used.

 

>> For some reason I checked the crystals to make sure I was using the 2.7kc
for XMIT.  I am.    I then turned the WIDTH from 250hz up to about 800hz.
The chirp is GONE!  As long as I don't turn the width low enough to engage
either the 400hz or 250hz filters, the signal on 20 is FINE.

 

>> I then tried 21mhz with the filters in various positions. NO ISSUE, NO
CHIRP.  This is the same for all other bands except for 14.0 mhz.

>>  I brought up the K3 Utility SW to check the filters.  They are set as
they should be.

>> I turned off the 400 and 250 filters and turned the WIDTH way down -
signal is fine.

>> Put the 400hz filter back in the configuration - CHIRP CHIRP

>> Took the 400hz out - put the 250hz in the configuration - NO CHIRP on VFO
A but CHIRP on VFO B

 

What do these filters have to do with transmit when only the 2.7kc is
selected?   GOT ME?

 

Current state:  

 

> 3.5 and 14.0 have bad signals when the 400hz and/or the 250hz filter are
in the configuration and being selected by WIDTH

> 3.5 has ripple on the CW note - not impacted by the RX filters

> 14.0 has a chirp - and it goes away as long as I only use the 2.7kc
filter.

> BOTH the 400hz and 250hz filters are OUT of the configuration until HELP
and SUGGESTIONS arrive.

 

 

Looking for HELP and SUGGESTIONS???   Perhaps I have some other memory
setting screwed up, but I doubt it.   Why only 3.5mhz and 14mhz??

 

Thanks!

 

73,

Bruce - N1LN

(aka: NC4KW)

               

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[Julian, G4ILO]

The other filters have a different offset so when going from TX to RX the VCO has to change. For some reason it is changing sluggishly and causing chirp. Have you done a VCO calibration?