[TenTec] Argonaut 505

[Bill Fuqua]

At 01:16 PM 12/17/2003 -0700, you wrote:
>Bill,
>
>Thanks for the input.  I am monitoring with another receiver in the shack 
>and with the Argonaut driving a Heathkit Cantenna.  I can hear an obvious 
>difference when I change the power supplies, the 210 and another regulated 
>AC supply produce a hummy cw note while my battery supply is clean.
>
>Jim


What had me thinking about this possibility was that you said you could not 
see any envelop on the O'scope. Is your scope sync-ed off the power line 
and horizontal set for about 5mS per division? Having FM is usual from a 
power supply if there is no AM as well.
Can you see ripple on the power supply?

73
Bill wa4lav


>   ----- Original Message -----
>   From: Bill Fuqua
>   To: tentec at contesting.com
>   Sent: Wednesday, December 17, 2003 12:20 PM
>   Subject: Re: [TenTec] Argonaut 505
>
>
>   How are you monitoring the hum when you transmit? Possibly another 
> receiver
>   in the hamshack?
>   If you are using another receiver near by it may not be real. Some 
> times RF
>   gets into the
>   power supply and the rectifier diodes that are switching on and off at 120
>   Hz rate amplitude
>   modulate it and it is re-radiated by the power cords.  If this happens the
>   solution is to ignore it or
>   put RF bypass capacitors across the rectifiers.
>
>   Usually Magnetic field coupling into the transmitter is only noticed when
>   transmitting phone due to the fact that the microphone preamplifier is
>   sensitive enough to amplify the small millivolt signal produced by the
>   magnetic field from the transformer.
>
>   73
>   Bill wa4lav
>
>
>   At 09:49 AM 12/17/2003 -0700, you wrote:
>   >Y'all,
>   >
>   >I just became a new owner of an Argonaut 505, the very first Argonaut and
>   >my first Ten Tec rig.  It came with the model 210 power supply.  I am
>   >noticing a 120 Hz hum on the transmitter note on CW and a corresponding
>   >hum on the SSB signal when I run the rig from the 210.  When I power it
>   >from a battery there is no hum.  It is most noticable on 40 meters which
>   >is where the local oscillator is tripling, and I don't see a hum on the
>   >wave-envelope with my HP1740A 100 mHz oscilloscope.  So it may be FM on
>   >the local oscillator.
>   >
>   >I would appreciate first of all a circuit diagram for the 210 power
>   >supply, and then of course any suggestions about what to do.  It is a
>   >really fun little rig when I run it from the battery.
>   >
>   >Thanks,
>   >
>   >Jim Hanlon, W8KGI
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