[Elecraft] K3S - High SWR on 6 Meters

[N4ST - Jim]

Thanks Jim,

It is a real puzzler.

-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On
Behalf Of Jim Brown
Sent: Tuesday, June 14, 2022 02:28
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3S - High SWR on 6 Meters

On 6/13/2022 11:05 PM, N4ST - Jim wrote:
> SWR is fine with CW, problem only occurs with FT8.  Same antenna, same
coax,
> same frequency.
> Only occurs on 6M.

I've seen guys trying to help asking questions for which I haven't seen 
answers. I'll try ONCE to help.

1. Describe the antenna. Where is it (with respect to the shack)?
	5el Cushcraft located 55 feet from the shack.
2. As others have observed, the first thing to check in any system when 
something like this happens is to suspect EVERYTHING in the antenna 
system, ESPECIALLY ever piece of coax and every connection. That means 
getting serious to check that every connector is wrench tight, and to 
"rattle" all cables and connectors while watching for any changes.
	By passed Daiwa antenna switch.  Swapped coax jumper cables.  
3. What WAS the SWR on CW? What was it on FT8?
	1.1-1.2 SWR on CW.  Meter pegged +10 on FT8
4. What happens if you click on TUNE in the software you're using for FT8?
	That is how I have done the FT8 testing.
5. What power did you use for each mode?
	Have used 50W & 100W on CW.  8W, 10W & 50W on FT8
	The FT8 SWR is fine at 8 watts, before K3S PA is engaged.  No good
at 10W when the PA kicks in.
6. Are any of your coax connectors, including adapters, junk? If they 
don't say Amphenol 83-1SP, or have a MIL spec number stamped on them, 
there a VERY good chance that they are JUNK. When I got back on the air 
in 2003, I filled my parts stash with all sorts of no-name adapters from 
ham vendors. Over the next 6-8 years, they caused me all sorts of grief. 
Flimsy construction, spring wire in elbow adapters, out of physical 
tolerance center conductors that don't mate well to form a solid 
contact. I had Tee adapters fall apart.
	I may have some "junk" connectors.  DX Engineering crimp/solder
PL-259s.
	Have swapped jumpers.  Bypassed antenna switch.  No observable
difference.
	FWIW, my TenTec Eagle is perfectly happy with the 6M beam,  70W FT8,
1.2 SWR.
	I suspect my "new" refurbished PA module from Elecraft has some
instability.

73, Jim K9YC

______________________________________________________________
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
Message delivered to hamshack at n4st.com