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Re: [Yaesu] FT-450 Tuner acting weird

To: Tom Osborne <w7why@frontier.com>, yaesu@contesting.com
Subject: Re: [Yaesu] FT-450 Tuner acting weird
From: Doug <dmcgarrett@optonline.net>
Date: Thu, 05 Mar 2015 22:11:05 -0500
List-post: <yaesu@contesting.com">mailto:yaesu@contesting.com>
On 03/05/2015 09:23 PM, Tom Osborne wrote:
Hi George

It is the same with 2 different antennas.  With he tuner off, both of the 
antennas are resonant about 3530.  It was working about a week ago and then all 
of a sudden it just quit working on 80. Funny that it works OK on all the other 
bands.

The funny thing is that I can hear the tuner trying to tune but the lights 
flicker and then go out.  When it gets done, the SWR is pegged out, even on the 
frequency the antenna is resonant on.

This is the radio that I usually keep in my camper for summertime camping.  I 
just brought it in to check it out last week. 73

Tom W7WHY



On 3/5/2015 5:19 PM, George K5KG wrote:
Is this a tuner problem, or an antenna problem?  Try tuning it on 80 with a 
different antenna to isolate the problem.

73, George k5kg

Sent from my iPhone

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All these automatic tuners operate by switching relays in and out. So there 
only a few possibilities, outside of digital corruption:

(I assume that the same directional coupler/detector is common to the other 
bands.)

One or more of the relay drivers is blown.

One or more of the lines that drive the drivers is not switching--possible 
digital corruption.

A tuned circuit that operates on the 80 meter band has gone bad--the capacitor 
open, maybe? (Look for bad solder joints, also.*)

One or more of the relays has become defective--I like this last option least; 
they should be good for a million or more operations.

I hope you have an oscilloscope--that would be my instrument of choice to look 
at the various possibilities.

*Since the tuner operates in a vibratory environment, with all the relays 
switching, a close inspection of the solder joints

is probably the _first_ thing you should do.

--doug, WA2SAY
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