[Elecraft] K4 Production Relase 28 and SWR display issues

[Andy Durbin]

"Here is what I've done for the test:

- bypass the internal KAT4 ATU
- de-tune my Palstar BT1500A external tuner for an SWR of about 1:2
- use the keyer to send in CW. SWR (bargraph in display) shows 1:2. Okay!
- use the MH4 to send in USB and say "aaaah". SWR shows 1:2. Okay!
- use the MH4 to send in AM (carrier only). SWR shows 1:1. Not okay! (?)
- use the MH4 to send in AM and additionally say "aaaah". SWR shows 1:2. Maybe okay. (??)
- use the MH4 to send in FM (carrier only). SWR shows 1:2. Okay!
- use the TUNE butten in WSJT-X to send in DATA. SWR shows 1:1. Not okay!

In every mode, using the TUNE button of the K4 shows an SWR of 1:2. Okay!"

For each of the cases that gives misleading 1:1 indication - What is the reading if you increase the output power?

Reason for the question is that KAT500 has an insensitive bridge and always gives misleading 1:1 SWR reading at low power.  I wrote code to invalidate  and dash my display of the serial data SWR based on forward power level.  Perhaps a similar issue in K4. 

Andy, k3wyc