K2 #4498 - Big problem

[F5UL]

 Hello the list,

 Sorry for the misunderstanding and the pass band used without necessities !
 It was not about the bouncing back but the msg concerned my K2

 Up to this morning, this K2 was a nice and good worker, with during the last
 six month about a thousand QSO under his belt !
 But this morning turning it on, I just got a vigorous howl ( very low freq nois !). I turn it off, and
 on after a few second.
 The Rx start normaly and the noise start again after
 a few second. Re-turn off and tunr on and no howl and Rx is working
 correctly!
 The set was in CW mode so I turn down power (to abt 2/3 watts)
 and close the key...
 The result is correct on 1.8, 3.5, 7.0 but nil on the rest of the bands.
 Closing the key a little longer  on 7.0 the rig goes to
 curent overange in abt 10/12 second and power fall down to zero.
 So power off, open the rig, remove the bottom cover and before removing the
 heat sink just check the resistance of driver and PA.
On Q6 (driver) E to Gnd 1.3 ohm, B to Gnd 76/80 ohms, and C to Gnd > 500 ohms.
 On Pa C to Gnd > 600 ohms, B to Gnd 120/130 ohm E to Gnd 0 (it's normal!).
They seems to be normals but any time I close the key I get High Cur after 5/6 seconds and power out ZERO !!
 I do not know what to do, so I will wait till tomorow and hope to get some
 indications from the list !
Thanks in advance guy, BCNU
72 Bob/F5UL

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[Don Wilhelm-3]

Bob,

First check your power supply and the cable connections between the Power
Supply and your K2.  The conditions you report are classic for a low voltage
at the K2 power connector and/or a high resistance (loose connection) in the
power supply path.

73,
Don W3FPR

> -----Original Message-----
>
>  Up to this morning, this K2 was a nice and good worker, with
> during the last
>  six month about a thousand QSO under his belt !
>  But this morning turning it on, I just got a vigorous howl (
> very low freq nois !). I turn it off, and
>  on after a few second.
>  The Rx start normaly and the noise start again after
>  a few second. Re-turn off and tunr on and no howl and Rx is working
>  correctly!
>  The set was in CW mode so I turn down power (to abt 2/3 watts)
>  and close the key...
>  The result is correct on 1.8, 3.5, 7.0 but nil on the rest of the bands.
>  Closing the key a little longer  on 7.0 the rig goes to
>  curent overange in abt 10/12 second and power fall down to zero.
>  So power off, open the rig, remove the bottom cover and before
> removing the
>  heat sink just check the resistance of driver and PA.
> On Q6 (driver) E to Gnd 1.3 ohm, B to Gnd 76/80 ohms, and C to
> Gnd > 500 ohms.
>  On Pa C to Gnd > 600 ohms, B to Gnd 120/130 ohm E to Gnd 0 (it's
> normal!).
> They seems to be normals but any time I close the key I get High
> Cur after 5/6 seconds and power out ZERO !!
>  I do not know what to do, so I will wait till tomorow and hope
> to get some
>  indications from the list !
> Thanks in advance guy, BCNU
> 72 Bob/F5UL
>
>

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