[Johnson] Solid State Power Supply in a Ranger
Sherrill Watkins
Sherrill.Watkins at dgs.virginia.gov
Mon Oct 18 13:32:44 EDT 2004
Bob: Is the VFO contained inside the Johnson Valiant and the seperate Model
122 VFO subject to the same catastropic damage that the one in the Ranger is
subject to because of the failure of the dropping resistor causing extensive
damage to the circuit board? Thank's - Sherrill W. k4own.
-----Original Message-----
From: Bob Sullivan [mailto:robert at isquare.com]
Sent: Monday, October 18, 2004 9:25 AM
To: Ross Stenberg; Tim Anderson - AG4XM; Johnson at Mailman. Qth. Net
Subject: RE: [Johnson] Solid State Power Supply in a Ranger
Ross,
I hope you have moved that dropping resistor out of the VFO enclosure! If
not I suspect you are slowing cooking the VFO boards. I always relocate
that dropping resistor to under the chassis. Some of the Ranger VFO's I
have seen are pretty bad due to the heat generated by this resistor.
73, Bob
WØYVA
My station: http://www.isquare.com/personal_pages/hardware-14.htm
At 07:19 AM 10/18/2004, Ross Stenberg wrote:
>Tim, I know the purists would object, but I have been running my Ranger
>II with SS rectifiers and the resulting higher voltages for the last
>four years without any problems. I did however increase the value of
>the 18K dropping resistor supplying 0A2 regulator for the VFO and used
>electrolytic caps with appropriate voltage ratings throughout.
>
> 73 Ross K9COX
>
>
> >>>I've solid stated the power supplies and beefed up the
> >>>electrolytics in
>my
>Ranger I and it's working fine but of course the B+ voltages are now
>too high. (Around 800 on the high B+ and 600 on the low.) I've been
>using a variac set at around 90 volts on the mains to drop them down to
>a safe range. Anybody have a more elegant solution to drop the B+? 73
>Tim Anderson, AG4XM
>
>
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