Hi,

I was just about to recommend sweeping with a NanoVNA. I have a temptiing unit that samples and attenuates signals sent through my Bird Wattmeter also made by Bird. I swept it and found that it did nor present 50 ohms below about 26 MHz. I have also swept the Drake dummy load and other elements I have all flat 50 Ohms into the UHF spectrum. Not a problem for VHF/UHF hams. But I am a forty meter ham and get nosebleeds starting at 15 meters and I go into paralysis at 10 meters! The VNA will help you with confidence in your equipment. I also recommend the TinySA. Those two instruments have amazing utility. Owners of the big buck famous maker gear tell us the Nano and Tiny are remarkably accurate. They also do not cost you your retirement funds.

73,

Bill  KU8H


On 8/18/26 13:51, Jim Whartenby via Milsurplus wrote:
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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