VA3UMA

Trio (Kenwood) TS-520 restoration:

The trip: Picked up this rig from an old timer on a very cold January night in 2009. When he said he was giving away the TS-520 as a "parts" radio I didn't think twice. I remember it was around 15:30, too late to embark on a 550kms journey from Toronto to Montreal, considering the fact that it had been snowing incessantly and the roads were trecherous - putting it mildly.

As time was very short and I had to get back to Toronto, we quickly closed the deal. To my pleasant surprise the OT threw in a KW-103 and a SP-520 that were not part of the initial deal.

TS-520 Specs: An old original advertisement and specs sheet can be seen here.

The OEM power transformer (L01-0214-05) was burnt and an attempt had been made to ressurect the rig with a T-11 power transformer, apparently cannibalized from a Yaesu FT-101.

A "ZD" or a "Z" transformer would've been a better choice due to similar driver/finals, but getting 'anything' that works on these 30 year old rigs is in itself a daunting task.

As received condition:

• Excellent cosmetic condition; over all 9/10 because the send /receive paddle was missing and the switch was pushed inside !!
• Power transformer was not the original. See here for the FT-101 transformer (T-11) tappings
• Excess (soldering) heat had done it's irreversible damage on the HV board
• Two HV diodes in the final plate voltage doubling circuitry were snipped very crudely to take them out of the circuit
• Driver plate and all (driver/PA) screen voltages were taken from the same 240 V tap. This resulted in very high screen voltages despite a dropping resistor
• 14 VDC was implemented on a separate crude board using just a single diode (half wave)
• VFO always stopped oscillating midway (around 250 on the dial)

Restoration begins:

This page is still under construction and my newly aquired "parts" TS-520 is still "vertical" on my workshop bench. I'll keep this page updated as I progress...

Index

Revised: 05/08/11.