[Kenwood] recommendation regarding Kenwood TS 2000

[Bryan Swadener via Kenwood]

The steady-state current of the T/R relays in the SB200, SB220, TL922 et al is one thing. The instantaneous current is quite another.  When your rig goes from RX to TX, the 0.02uF capacitance across the ANT RELAY jack in these legacy amplifiers is discharged, producing a brief 6A current pulse.  Eventually, the 1A-rated relay contacts inside the rig weld themselves closed.

Richard Measures, AG6K also noticed this, and recommends adding a small resistance (less than 100 ohms) in series with the ANT RELAY jack. Decrease the resistance until the amplifier _just barely_ reliably goes into TX mode.  A 1/4W resistor is fine.

If you want the best setup, forget about relay drivers, rip out the S-L-O-W relay, and replace with the W7RY setup.  Jim sells a bare PCB that, for the Heath SB220 and Kenwood TL922 amplifiers, gives you low voltage/current control of FAST and QUIET relays, as well as electronic bias regulation & switching. By the time you're done, you've spent about $100.

vy 73,
Bryan WA7PRC

Date: Mon, 11 Aug 2014 13:53:20 -0500
>From: Clif 
>To: Kenwood Mail List
>Subject: Re: [Kenwood] recommendation regarding Kenwood TS 2000
>
>The relay in the Kenwood will handle 600ma @ 120v or 2A @ 30V. Please do
>not put out as gospel needing relays on all SS rigs. Ain't true.
>