I mis-spoke, the TO-220 package is rated to dissipate a watt with no
heat sink at only 70C. at 25C it can dissipate around 2 watts. Still way
more than it's dissipating in this application.
Dale,
NV8U
Dale J. Robertson wrote:
Jim,
If you can touch the VR it's not even close to too hot!
that thing is rated to dissipate a watt with no heat sink at 100C
ambient (room) temp.
Dale
NV8U
James R. Elledge wrote:
--- In [email protected]
<mailto:softrock40%40yahoogroups.com>, "Tony Parks" <[EMAIL PROTECTED]> wrote:
>
> Hi Jim,
>
> Do you have a measurement of the current from the 13.8 volts power
supply when the v8.0 (?) is running on various bands? Also do you
have a temperature measurement on the 5 volt regulator?
>
> I think the typical current is around 100 mA for about 0.8 watts of
heat in the 5 volt TO220 case regulator.
>
> 73,
> Tony KB9YIG
> ----- Original Message -----
> From: James R. Elledge
> To: [email protected] <mailto:softrock40%40yahoogroups.com>
> Sent: Wednesday, May 07, 2008 10:59 AM
> Subject: [softrock40] SR LITE V8.x SUGGESTION
>
>
> The 7805 VR gets a bit warm when using a 12V or 13.8V power
supply,
> another VR (9V perhaps) between the 12/13.8V PS would help. This
> technique has been used successfully by others (and myself) to
help
> with the heat problem when using standard 12/13.8 PS's.
>
> Jim - KB2XJ
>
Hi Tony
I do not have a temp probe for accurate measurements (use my finger).
The VR is not exactly HOT but a bit warm to me. A small HS may fit
under the reg to keep me from getting excited. The Si chip also a
bit warm after a few minutes of op. I can get an accurate current
reading, 98.54 mA at 12.0V (default freq). Only checked output at the
default freq, its ok. Need to locate the sw's settings vs output
freq , will look in files to locate.
I will make a chart for freq vs current when I can (dog sitting/house
sitting for the next four or five days-sister out of town).
Jim - KB2XJ
