Here is  S11. 

@30 MHz 48.9+j21.35

@15MHz 44.6+j9.3

@ 5MHz 44.5+j1.9

@300kHz 47.4+-j0.57

From: Jim Whartenby <[email protected]>
Sent: Tuesday, August 18, 2026 12:52 PM
To: Francesco Ledda <[email protected]>
Cc: [email protected]
Subject: Re: [Milsurplus] TS-234A/UP

Francesco

I wonder how non-inductive the resistors actually are?  This would limit the upper frequency that one can safely use.  I believe what limits the upper frequency of most dummy loads is actually the detector network used to measure input power. 

Do you have a tiny VNA for testing the resistor network?

Jim

Logic is a systematic method of coming to the wrong conclusion with confidence. Murphy

On Tuesday, August 18, 2026 at 11:50:30 AM CDT, Francesco Ledda <[email protected]> wrote:

Well, my TS-234A is indeed 50 ohm! It has 4 large 200 ohm resistors. There are no signs of manumission and looks original.  I am as puzzled as you probably will be. If interested, I can forward a picture of the inside. 

Best, Francesco K5URG

Sent from my iPad

On Aug 17, 2026, at 19:15, Jim Whartenby via Milsurplus <[email protected]> wrote:

16 ohms is 1/3 of 50 ohms so it might be possible that there are 3 each 50 ohm @ 425 watt elements in parallel.

So it might still be useable as a standard 50 ohm load at reduced power.

Jim

Logic is a systematic method of coming to the wrong conclusion with confidence. Murphy

On Monday, August 17, 2026 at 03:58:47 PM CDT, [email protected] <[email protected]> wrote:

Thank you, all!

From: [email protected] <[email protected]> On Behalf Of hwhall--- via Milsurplus
Sent: Monday, August 17, 2026 3:51 PM
To: [email protected]; [email protected]
Subject: Re: [Milsurplus] TS-234A/UP

Can we post images here? Let's see.

Wayne

WB4OGM

On Monday, August 17, 2026 at 02:14:20 PM MDT, [email protected] <[email protected]> wrote:

Hi All,

I have here a dummy load labeled TS-234A/UP.  It says 1275W, but does not specify the frequency range. 

Does anybody have a spec of such thing that can share with me?

Thank you!

Best, Francesco K5URG

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