[Elecraft] Re: Astron RS-35M - Problem Related to RF (FIXED)!!!

[lbailey@aep.com]

Connected station ground to TS-440s & all works fine. 
HOORAY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Remove the ground & power supply shuts down on transmit.  Boy did I cover 
alot of ground before I got back to something as simple as installing a 
ground.

73 & TNX to all for your suggestions de K5AVJ
K2 #1411

================HISTORY BELOW==================================
Looks like the problem is RF.  I put a dummy load on the rig & the power 
supply works fine.....delivers 16 amps on CW key-down.  I discovered the 
problem when I was operating 40 meters, so today, I checked out 75 mtr. & 
20 mtr. & the rig works fine.  Power supply still shuts down on 40 meters 
so I will make the RF mods I have found & see how that works.

No problem on my K2 but my TS 440S shuts power supply down.  I'm in the 
final stages of finishing up the KPA100 so I'm stopping to fix the PS 
before proceeding.  (Antenna is a G5RV)  Wish I had the K2/100 ready to go 
so I could see if it has the same problem.

(RF mod - .001 microfarad cap across pins 2 & 3 on LM-723 per KB7KBT)

UPDATE ON RF MOD...
WHOOPS....Still not fixed.....

Looks like I'm gonna have to do more than just adding the 0.001 capacitor. 
 Since this PS has been mated with the RS-35M for some time, I suspect 
that my G5RV antenna is acting up or the antenna tuner in the TS-440s has 
a problem.  I did check my antenna about 2 weeks ago & I was alarmed at 
the degree of corrosion on the twin lead bolted connection to coax/balun 
connector.  Think I'd better redo that connection & wrap it with duct seal 
to keep the mosture out.

Guess another easy options are to relocate the power supply to the floor. 
Also rig is not grounded.


>>>>>>>>>>>Earlier Note Below<<<<<<<<<<<<
================================================================= 
My K2 power supply, Astron RS-35M, will put out low amperage...~2.5 
amps...to drive my K2, but when higher amperage is req'd for my TS440s & 
my almost finished KPA100, the output voltage goes to "0."  When I cycle 
the on-off switch, the voltage comes back up but still limited amp 
capability.  Receive works fine on the TS440s but when I key the mike, the 
rig goes dead & the voltmeter on the RS-35M reads "zero." 

Output voltage under low current demand......14.1 VDC & 0.77 mVAC ripple 
with Fluke 867B 
Output voltage after high current demand.......0.8 VDC & 0.6 mVAC ripple 

History...this power supply is about 15-20 years old & all I've done is 
tweak the output voltage via R5 up to 14.1 volts so that I would have 
ample charging voltage on the K2 battery.....I did this tweak about 2 yr. 
ago.  (This power supply stays on continuously) 
================================================================ 

I have replaced the LM723 & lowered the supply voltage to 13.6 v but to no 
avail. 



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