[Yaesu] RE: Yaesu Digest, Vol 19, Issue 10

["Marinos Markomanolakis, M.D." <sv9dru@hotmail.com>]

Dear Marty,

My 1000D has the same low hum noticeable only when using the headphones and 
having the AF pot all the way CCW. I have seen this in other rigs too TR7, 
Tube radios etc and it is related to the use of low impedance headphones.
If you try using headphones with low (16 Ohm) impedance that either have 
volume control or you can add a variable resistance in series with them 
before going to the radio, you will see the problem disappearing when you 
increase the resistance and returning when going back towards the 16 Ohm.
Then you can check the added resistance value with a multimeter and add a 
small (or 2 one in each channel) resistor within a Radio Shack large stereo 
plug and then connect your headphones through it to the 1000D.
Of course in doing so you will have some attenuation in your audio but the 
hum will be gone.

Hope this helps,

73,
Marinos, sv9dru/w4 or KI4GIN


> From: yaesu-request@contesting.com
> Reply-To: yaesu@contesting.com
> To: yaesu@contesting.com
> Subject: Yaesu Digest, Vol 19, Issue 10
> Date: Sun, 25 Jul 2004 12:00:36 -0400 (EDT)
>
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> Today's Topics:
>
>    1. FT-1000 60 Hz Audio Hum (Marty Rosenzweig)
>    2. Re: FT-1000 60 Hz Audio Hum (Alan)
>    3. Re: FT-1000 60 Hz Audio Hum (Steve Lawrence)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 24 Jul 2004 12:58:18 -0600
> From: Marty Rosenzweig <marty@cmn.net>
> Subject: [Yaesu] FT-1000 60 Hz Audio Hum
> To: yaesu@contesting.com
> Message-ID: <4102B14A.4000204@cmn.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Greetings,
> I have a 1992 FT-1000 which, with the RF and AF gain CCW (off) and
> everything disconnected from the radio except a pair of Yaesu
> headphones, has a very noticeable 60 Hz hum (about 5 mv on the scope,
> both channels (ie., main and sub in "stereo"). The hum level doesn't
> vary with the AF gain control, the AF output (which isn't very useful)
> is clean and the hum disappears into the "normal" volume level but
> doesn't seem "right"! I've been living with the hum for a couple of
> years (maybe since '92!) and my memory is hazy but I think I listened to
> friend's 1000 and heard the same hum. The -9V buss measures 9.3V and the
> +9V is 8.65V but both look pretty clean.
> Has anyone fixed this in the 1000 (Yaesu tech support had never heard of
> the problem and wasn't successful in isolating it for me...I don't have
> the service manual) or, at minimum, could a few owners of the FT 1000
> (and 1000D) experiment  with their radios and let me know if they hear a
> hum under the given operating conditions?
> Since this may not be of general interest to the list, e-mail me
> directly and I'll report the results.
>
> Thanks,
>
> Marty
> WO0Q
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Sat, 24 Jul 2004 20:41:54 +0100
> From: "Alan" <g4zfq@wight365.net>
> Subject: Re: [Yaesu] FT-1000 60 Hz Audio Hum
> To: <yaesu@contesting.com>
> Message-ID: <007d01c471c1$ea0d8d40$0601a8c0@c400>
> Content-Type: text/plain;       charset="iso-8859-1"
>
>
> ----- Original Message -----
> From: "Marty Rosenzweig"
> > Since this may not be of general interest to the list, e-mail me
> > directly and I'll report the results.
> >
> I think you are probably being over critical but I would be interested in
> what others think.
> I don't even have an FT1000!
>
> 73 Alan G4ZFQ
>
>
>
> ------------------------------
>
> Message: 3
> Date: Sat, 24 Jul 2004 14:41:19 -0700
> From: Steve Lawrence <smlx@earthlink.net>
> Subject: Re: [Yaesu] FT-1000 60 Hz Audio Hum
> To: Marty Rosenzweig <marty@cmn.net>
> Cc: yaesu@contesting.com
> Message-ID: <32B31FC7-DDBA-11D8-85E1-0003931129C6@earthlink.net>
> Content-Type: text/plain; charset=US-ASCII; format=flowed
>
> Marty - My 1000D of approximately the same vintage does not exhibit any
> audio hum. I did have some RF birdie problems which were caused by
> loose screws on several boards. I posted that fix to this list some
> time ago.
>
> http://dayton.akorn.net/pipermail/yaesu/2003-February/004280.html
>
> and the problem has not returned.
>
> I would suggest that you try cleaning and re-seating all of the
> connectors in the audio chain and look to tighten any loose PC board
> mounting screws you find.
>
> Good luck & 73, Steve WB6RSE
>
>
>
> ------------------------------
>
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> End of Yaesu Digest, Vol 19, Issue 10
> *************************************

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