[Amps] SB220 Sick

[Carl]

>I know now, but when I started the answer and before being interrupted six
> times, there was no answer. I didn't think about going back to see if
> anyone had  answered before hitting the send button. Very sorry for any
> aggravation caused  by this oversight and I will definitely try to be more 
> aware in
> the  future.

Nice retort!
Carl

>
> One added thought: the band switch index on these old amplifiers get dry
> and stiff. If the index is at the rear of the assembly (can't remember if 
> the
> SB220 is or not)  it puts extra stress on the shaft turning torque
> requirements. That can lead to a slipped shaft.
>
> Now, the next question is: how to free up one of these indexes?
>
> 73,
> Gerald K5GW
>
>
>
>
> In a message dated 4/7/2010 1:14:18 P.M. Central Daylight Time,
> stevek at jmr.com writes:
>
> Already  said that!
>
> WB2WIK/6
>
>
>
>
> -----Original  Message-----
> From: amps-bounces at contesting.com  [mailto:amps-bounces at contesting.com]
> On Behalf Of TexasRF at aol.com
> Sent:  Wednesday, April 07, 2010 11:10 AM
> To: pcb4u at verizon.net;  amps at contesting.com
> Subject: Re: [Amps] SB220 Sick
>
> Jay, you might  want to make sure the bandswitch shaft hasn't slipped and
>
> the input  part is not on the band you think it is on.
>
> 73,
> Gerald  K5GW
>
>
>
>
> In a message dated 4/7/2010 12:48:15 P.M. Central  Daylight Time,
> pcb4u at verizon.net writes:
>
> HI   all
>
> Need some help. I have a friends SB220 that does not accept  RF  drive.
> Following info
>
> 1) Plate voltage good at tubes
> 2)  Looks like  30 ohm parasitic resistors/cap (aftermarket) are  good,
> both
> tubes
> 3) Relay  closes...TUNE position plate idles  at 100ma
> 4) When relay closed I do have  a DC path from RF input via  relay to
> tube
> just prior to .01uf coupling  capacitor.
> 5) In  standby RF path good from INPUT to OUTPUT
> 6) Tubes do  not glow  blue
> 7) The tubes appear OK (physically), passed the "shame next  to  ear"
> test
> 8) No grid current
> 9) Driving rig (TS950) shows  INFINITE  SWR which (to me) indicates an
> open
> or short (RF wise)  in input.
> 10) 5 volt  zener OK when relay energized
>
> I am  thinking it could be the .01uf  coupler to the   filaments
>
> Thoughts?
>
> Jay
> W2IJ
>
>
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