Re: 432MHz ATU?

Neil Smith G4DBN

If you can get hold of a VNA and see what the impedance looks like, you could make a two-stub tuner from coax. 6:1 sounds like the coax outer has corroded away or something, was the match ever OK, or has it always been off? Does it change across  the band? If so, what is the curve like?

A NanoVNA would illuminate the problem. Loads of examples of two-stub tuners out on the internet.

6:1 sounds like something disastrous though.

Neil G4DBN

On 15/02/2021 23:12, ian hope (2E0IJH) wrote:
Sent: Monday, February 15, 2021 at 11:03 PM
From: "g4zod@... via" <g4zod@...>
Subject: [UKMicrowaves] 432MHz ATU?

I have a long term problem with my 17 element MET Yagi. The VSWR is rather high at about 6-1 and I cannot risk blowing my new radio!

I have no way of taking down my pump up mast to adjust the matching on the antenna. The current restrictions mean I cannot get my fellow club members around to help me drop the mast.

As this means my activities on 432MHz have to be put on hold for possibly many more months I need to find an interim solution. In the mist and cobwebs of mind I recall an ATU for UHF frequencies. I did a quick search and nothing came up.

Can any group member confirm if an ATU for 432 MHz is practical and if so any reference to one?

Many thanks

Julian G4ZOD


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