[NLRS] The woes of 13.8 vdc

Sat, 12 Jul 2003 15:07:43 -0500

Hi Jon,

I think that by the time you have a solution to supplying the 6-8 amps for a
long period  the cost of an if rig would be a better solution.    If you do
solve the higher voltage you will still be a bit shy on battery power if you
have a long outing.   The FT100D running all day  takes a lot of power and
would require a large battery supply.   An if rig that draws 1 to 2 amps is
a good solution.  Maybe  the gang has a good solution

73 Bob W�AUS

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of [email protected]
Sent: Saturday, July 12, 2003 12:26 PM
To: [email protected]
Subject: [NLRS] The woes of 13.8 vdc

I need some help from you DC power guys.   Here is my problem.  For now, I'm
using my FT100D for my IF rig on 10 GHz.   The FT100D is really an amazing
radio for a HF/VHF guy like me, it really does a lot of stuff !   One thing
that
it does not excel in is power management.   For example, my 10 GHz
transverter
with 1 watt amp takes about 1 amp at 13.8 vdc but the FT100D, throttled back
to just 2 watts of drive at 144 MHz still sucks about 6 to 7 amps or so on
transmit.    Don't ask me why .... probably because of the broad band final
section (hey, it does 1.8 to 440 MHz).   A fully charged battery like a deep
cycle
battery will provide about 12.5 or 12.6 vdc that drops to around 12.1 to
12.0
vdc on transmit.     This gets worse as the battery is depleted.   The specs
on the FT100d are 13.8vdc +/- 10%, or a range of 12.42 vdc to 15.18 vdc.
As
you can see, even with a fully charged battery, I am already operating at or
slightly below the bottom end of the VDC spec for the FT100d.

So, without going to another IF rig, here are some options.   I'm wondering
if anyone else has tried these options and if so how it worked for them, or,
if
there are some other options.

1.  Add a single cell in series.   A single cell lead acid is about 2.1 vdc
so this would make the fully charged voltage around 14.7 vdc which is within
the upper spec of the FT100d of 15.2 vdc with about 0.5 vdc of headroom.
The
cell would need to pass 6 or 7 amps when I transmitted.   Anyone have any
ideas
where one can find a single cell lead acid rechargable battery like this ?
How about a seven cell lead acid deep cycle (one can ask) ?

2.  Go with a two battery system to provide18 vdc or 24 vdc and build a
regulator to regulate at 13.8 vdc.    The regulator would need to pass
around 8
amps and need to dissipate about 80 watts when transmitting (8 amps x
(24-14vdc))
.... a bit less if you use an 18 vdc system.   Anyone done this ?

3.   Go with a DC/DC converter of some type.   Some unregulated DC voltage
in, a regulated 13.8vdc out.   Sounds kind of expensive and messy to me,
especially when running portable.   Anyone have any experience with doing
this ?   Is
there anything commercial available.

4.   Bite the bullet and get a different IF rig that uses current more
appropriate for its output power and that has a higher tolerance DC voltage
input
range.    What are good candidates?

73, Jon
W0ZQ

--- StripMime Report -- processed MIME parts ---
multipart/alternative
  text/plain (text body -- kept)
  text/html
The reason this message is shown is because the post was in HTML
or had an attachment.  Attachments are not allowed.  To learn how
to post in Plain-Text go to: http://www.expita.com/nomime.html  ---
_______________________________________________
NLRS mailing list
[email protected]
http://mailman.qth.net/mailman/listinfo/nlrs