TS530S problem

[G4OTU]

Running the TS530S in SSB mode on 40 meter I suddenly had a series of popping noises from the audio and power out dropped to approx 45%.

Radio thereafter would not tune up beyond approx 45W out

In the IP position the best tuned dip is about 175ma.Even with Drive fully advanced no more output was a possible.

I am guessing that either one 6146B has died (or could it be the driver)?

Opinions please ...and also does anyone know where I can find a blow-by-blow guide to changing the tubes(valves)?


Radio has been recently purchased - it had been little used by previous owner - but must be around 15-20 yrs old.

[KD7MSC]

Lots of great info on http://www.k4eaa.com/ for Kenwood hybrids.

[W5RKL]

Unless you know for sure the driver and/or one or both final amplifier tubes are bad, never assume they are the source of your problem.

You did not say what the HV meter shows in transmit. The HV meter scale is RED and the pointer should point to approximately 925VDC. The 830 must be in transmit for the meter to display the HV. Simply switch to USB or LSB, press the microphone PTT button but do NOT speak into the microphone, set the meter switch to HV, and read the HV from the RED scale.


73s
Mike

[G4OTU]

HV is showing about 450VDC...about half value then.

Radio is a 530S not a 830.

Is there any way I can check the tubes by removing /substituing one at a time and seeing which one provides power and which does not ?.... obviously I realise that if it is a tube gone then both need to be replaced.

[W5RKL]

HV is showing about 450VDC...about half value then.

Radio is a 530S not a 830.

Is there any way I can check the tubes by removing /substituing one at a time and seeing which one provides power and which does not ?.... obviously I realise that if it is a tube gone then both need to be replaced.

Sorry I got the model wrong. As far as your problem is concerned and the HV supplies, it doesn't matter which radio it is, 530 or 830, they both have the same HV supply and same HV components.

Your problem is not caused by either the driver or final tubes. Your problem is caused by one of the HV filter capacitors have failed!

The capacitors are located directly behind the VFO. There are 2 of them, each capacitor is mounted in a ring clamp that is held to the chassis by a screw.

Replace both capacitors, not just one. Each capacitor is 100ufd at 500VDC. The capacitors are wired in "series" in a voltage doubling supply. Make sure you pay close attention when replacing the capacitors so you connected them in series so the polarity pins are connected properly.

73s
Mike

[G4OTU]

Thanks Mike - will come back and let you know how I get on.

73

Dave

[G4OTU]

A quick update - yes it turned out to be a blown cap, a new pair is on order and should be with me after the weekend.

Thanks to all.

73

[W9GB]

Make sure you pay CLOSE attention, when replacing the capacitors, to connect them in series and
that the POLARITY pins/tabs are connected PROPERLY.

AMEN. A wiring mistake here ... is like wiring a firecracker inside the radio !
====
Frequent replacement item for the Kenwood hybrids .. many of these Kenwood transceivers are now > 30 years old.

Make sure your replacements are rated for 500 VDC

w9gb

[W5RKL]

Thanks Mike - will come back and let you know how I get on.

73

Dave

A quick update - yes it turned out to be a blown cap, a new pair is on order and should be with me after the weekend.

Thanks to all.

73

Did the capacitor arrive and have you installed them yet? How's the 530 working?

73s
Mike