[Elecraft] K144XV issues in K3S - audio distortion and fading signals over time

[hdv]

So the problem is clearly in the transvertor.Given the fact that both rx and tx follow roughly the same pattern a common cause seems to be logical.That could be voltage or oscillator.Check if the voltage remains constant on both rx and tx circuits. Also check the oscillator signal and level with a scoop or spectrum analyser.Most probably it is heat related. Given the fact that audio distortion starts rather quickly the oscillator would be my prime suspect.73 HenkPA0CVerzonden vanaf mijn Samsung Galaxy-smartphone.
-------- Oorspronkelijk bericht --------Van: Hank <hbjr at optilink.us> Datum: 24-05-19  19:28  (GMT+01:00) Aan: hdv <hdv at kpnplanet.nl> Cc: Elecraft Reflector <elecraft at mailman.qth.net> Onderwerp: Re[2]: [Elecraft] K144XV issues in K3S - audio distortion and fading signals over time 
OK...here are some test results:

 - Neither problem occurs on 10m FM

 - The output power does also diminish on 2 meters - roughly follows the reception "weakening".  The S-Meter went from 60 over S9 to S8 over the period of 45 minutes and the output power (measured by a Bird WM) fell from 12 watts to below 5.
 - The audio distorts almost immediately
 - no testing on 2 meter AM or SSB yet

I did notice that the "weakening" occurs faster with lots of TX use.  So maybe it is heat related??  The problem is that it doesn't require much TX time at all - very little.  I seem to recall running the module at only a few watts out (like 2), and I could rag chew on FM for 45 minutes and the output power was never attenuated by protection circuits.  Running the module now at -9.0db pwr setting causes the effect to happen within just a few minutes.  


If I turn the K3S off and let it sit for 30 minutes, and try the transverter again, it works fine.  BUT after the rig sits on for 20 - 30 mins (NO TX), the received FM signal starts to "weaken".  Distortion starts almost immediately.

The K144XV is on the latest code release and I double-checked the 144 and 146 offsets as printed on the module to be sure they matched the menu settings - all good.

What gives??  I know the transverter has got to be more robust than that!!!

Hank
K4HYJ
K3S, P3, KX3

 



----- Original Message -----
From: hdv (hdv at kpnplanet.nl)Date: 05/23/19 13:47To: Hank (hbjr at optilink.us)Cc: Elecraft Reflector (elecraft at mailman.qth.net)Subject: Re: [Elecraft] K144XV issues in K3S


Just some questions to understand the problem better.
Is the audio issue only happening in FM or also in other modes?
Try FM on HF with someone close and see if if it is really caused by the K144

Does the K144 output also drops or is that stable.

73 Henk
PA0C




Verzonden vanaf mijn Samsung Galaxy-smartphone.


-------- Oorspronkelijk bericht --------
Van: Nr4c <nr4c at widomaker.com>
Datum: 23-05-19 19:32 (GMT+01:00)
Aan: Hank <hbjr at optilink.us>
Cc: Hank Blackwood <k4hyj at arrl.net>, Elecraft Reflector <elecraft at mailman.qth.net>
Onderwerp: Re: [Elecraft] K144XV issues in K3S

Frequency drift comes to mind.The HF ATU probably won't do anything for VHF.Let the radio warm up for half an hour before doing anything with VHF.Remember 1PPM at VHF is 144 Hertz.You need the high def oscillator and maybe the Ref In.Sent from my iPhone...nr4c. bill> On May 23, 2019, at 1:05 PM, Hank <hbjr at optilink.us> wrote:>>> Hey Folks...  >> I have noticed 2 unusual issues with my recently installed K144XV.  I bought it used from a list member and installed it a few months ago.  It seems to work ok but after some extended use (which recently begun) it is does 2 things: after it has been in use (even just monitoring) for local FM repeater work, the S-Meter on the K3S starts to read lower and lower (by as much as 3 S-Units) for the same repeater signal; and 2 - the audio becomes a little distorted on stronger signals (the ATT makes no difference in the audio distortion).>> The audio happens almost immediately after turning up the rig, but the signal "weakening" takes 10 to 15 minutes of the transverter being active (active band on K3S).  It will occur faster it is being used (transmitting).  I have it set to very low power (display reads -6db), and it will still show "weakening" on the S-Meter during reception after using it.  I noticed it fist doing some longer packet transmissions, but it will also happen after a period of time of just listening.>> The audio distortion is not as noticeable on signals below S-9, but listening in headphones will reveal the distortion is still there.>>> The K3S currently has the standard TXCO installed and no reference lock on the K144XV.  The 13khz filter is installed in the main receiver.  I have no external reference board installed in the K3S.  I have ordered the higher stability TXCO for the K3S and the K144XV reference lock, but have not received them yet from Elecraft.>>> The audio on HF is OK and the S-Meter does not seem to "weaken" in a similar fashion when monitoring strong net signals over time.>>> Any ideas?>> Hank> K4HYJ> K3S, P3, KX3>>>>>>>> ______________________________________________________________> Elecraft mailing list> Home: http://mailman.qth.net/mailman/listinfo/elecraft> Help: http://mailman.qth.net/mmfaq.htm> Post: mailto:Elecraft at 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 listHome: http://mailman.qth.net/mailman/listinfo/elecraftHelp: http://mailman.qth.net/mmfaq.htmPost: mailto:Elecraft at mailman.qth.netThis list hosted by: http://www.qsl.netPlease help support this email list: http://www.qsl.net/donate.html