Discussion in '"Boat Anchor" & Classic Equipment' started by KD5NDQ, Apr 14, 2019 at 1:41 AM.
The ones in the HV cage also ?
Are all of the wafers aligned properly ?
Try cleaning the Relay Contacts. I believe there are two relays in the TS-520 - clean both of them.
Yes and yes. The capacitor plates fully meshed has the PLATE indictaor just a little CCW of 3.5.
Another question: Does this happen on all bands, or just the lower (20M and down) ones?
Not TUNE, which runs greatly reduced power.
What is Ip in CW with CAR control advanced so that the ALC meter indicates? Should be 200mA or more. And if it is, what does "HV" read at that time? It should drop a bit lower than when "idling," e.g., from maybe 880V down to 800V or something. That drop would be normal under full load, it's a voltage-doubler power supply.
It's possible the Band Switch shaft coupler is cracked/broken, preventing the band switch
wafer inside the final amplifier from rotating the same as the main band switch wafers
on the RF Unit board. When this happens, the final amplifier band switch wafer will not
rotate properly with the RF Unit band switch wafers, resulting in no dip in PI current
in TUNE and CW mode.
To check the band switch coupler, power the 530 OFF, remove the covers, remove the
cover on the final amplifier, remove the front 6146, and pay attention to the band switch
assembly inside the final amplifier while rotating the band switch knob. The final amp
switch and the RF Unit switches should rotate exactly the same. If they do not, the final
amp switch does not rotate, then the coupler is more than likely cracked/broken and
needs to be replaced.
Steps to replace a cracked/broken band switch shaft coupler in a Kenwood TS-530.
Step 3 below that states to slide the band switch shaft from the coupler, do NOT remove
the band switch knob and do NOT remove the long band switch shaft from the radio!!
Slide the long band switch shaft out towards the front of the radio just enough to clear
the coupler so the coupler can be removed!!!
1. Removing the front 6146 final tube provides access to the band switch assembly
inside the final amplifier enclosure and the coupler set screws. Do not attempt to
loosen the coupler set screws without removing the front 6146 final tube.
2. Set the Band Switch to 3.5.
3. Loosen both sets of set screws and gently pull the band knob and long switch shaft out
towards the front of the radio just enough to remove the coupler
4. Look closely at the final amplifier band switch assembly shaft inside the final amplifier.
There are '2" flat spots on the switch shaft. Rotate the final amplifier switch assembly shaft
inside the final amplifier so the flat spots are as follows:
One flat spot is exactly horizontal on the top of the shaft and the other flat spot is exactly
vertical on the side of the shaft closest to the front final amplifier tube. The shaft flat spots,
when the shaft is set correctly, will be like an "Upside down L" as viewed from the front of the
radio!! The bottom of the "L" will be on top exactly horizontal and the vertical side of the "L" will on
the "right", exactly vertical. The band switch shaft inside the final amplifier must be exactly as
5. Slide the coupler onto the final amplifier enclosure switch shaft assembly and tighten
the sets screws on that final amplifier band switch shaft end of the coupler.
6. Rotate the band switch knob so the knob points to exactly "10" (NOT 10 meters)
7. Slide the long band switch shaft into the other end of the coupler and tighten the set
8. Rotate the band switch and watch the band switch assembly inside the final amplifier
enclosure, it should rotate exactly the same as the long band switch shaft. If it does then
replace the final tube, the cover over the final amplifier, the top and bottom covers on the
radio, you're done.
If you want to see where the final amplifier band switch assembly is located and where the
coupler set screws are accessed, look at Ken, K4EAA website link below
There is a mistype in my previous response. I typed "PI" instead of
"IP" in the last sentence of the first paragraph.
In TUNE mode the final amplifier screen voltage is reduced by approximately 50%
which will result in a reduction in the final tube IP meter (cathode current) indication.
In CW and any SSB mode the final tube screen voltage is returned to it's normal higher
voltage level. Switch to CW mode, turn VOX ON, and press the CW key, the IP meter indication
should be higher. If rotating the PLATE control does not result in a "DIP" in IP meter indication
when the PLATE knob pointer points within the White silk screen label of the band switch
setting then it's quite possible the band switch coupler is broken. Cracked/Broken Band
Switch couplers is not uncommon in these Kenwood hybrid models. I've had to replace the
Band Switch coupler in a few TS-530s in the past.
It reads roughly 75ma
75mA key down on CW indicates something's definitely wrong.