Yaesu 450d no tx or rx from 24-30mhz

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LondonCbRadio
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Yaesu 450d no tx or rx from 24-30mhz

Post by LondonCbRadio »

Ok so i just got me a yaesu 450d but here is the problem it won't rx or tx from 24-30mhz. I've tried by passing the atu and still the same thing. I've just had a look for dry joints and all seems ok. When i tx it showing on my psu that it's drawing power but the same type of power that it would draw if you had a high swr. I'm not going to send it for repair so please don't recommend shops if i can't get it working it will just stay gathering dust. It has some sentimental value. Any help would be great.
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Buick Mackane
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by Buick Mackane »

I'm by no means an expert but i would suspect one of the bandpass filter relay's is faulty
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by Buick Mackane »

It's possible if the radio has been modified to TX on 11m that the bandpass filters have been damaged
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by LondonCbRadio »

Buick Mackane wrote: 29 Mar 2023, 16:41 It's possible if the radio has been modified to TX on 11m that the bandpass filters have been damaged
The person was using it on 11 meters at the time it went bad. I'll have to dig out a rf probe and check it out when i have the time thanks.
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ch25
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by ch25 »

Check VCO voltage(s) first. Use plastic or ceramic tool to adjust. Do not break ferrite cores.
vco.jpg
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LondonCbRadio
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by LondonCbRadio »

ch25 wrote: 29 Mar 2023, 18:06 Check VCO voltage(s) first. Use plastic or ceramic tool to adjust. Do not break ferrite cores.

vco.jpg
Checked and it's fine.
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by LondonCbRadio »

Anyone have any other clues ?
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ch25
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by ch25 »

BPF7 is 21.5-33MHz. Is radio working between 21.5 and 24?
Also try to bypass tuner.
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by LondonCbRadio »

It works on 21.5 - 24mhz. I've also tried bypassing the ATU and it's still the same.
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by LondonCbRadio »

Sorry i made i mistake it don't work from 21.500mhz - 33mhz.
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by Buick Mackane »

Take it you've tried a factory reset ?
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by LondonCbRadio »

Yeah tried that didn't do nothing.
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by ch25 »

LondonCbRadio wrote: 03 May 2023, 11:17 Sorry i made i mistake it don't work from 21.500mhz - 33mhz.
So BPF7 or it's logic is suspected. Check if it get switching signal (J2003), than check switching diodes of BPF7, finally bypass it with some capacitor.
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by LondonCbRadio »

Sorry bypass what ?
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Re: Yaesu 450d no tx or rx from 24-30mhz

Post by Buick Mackane »

LondonCbRadio wrote: 19 May 2023, 16:55 Sorry bypass what ?
I Presume he means the band pass filter
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