I have
been a Icom user for years and most of the SCS TNC's have the ability to draw
power from the Rig via the communication cord. This means that I have not
had to run many power cables for the SCS modems while using Icom rigs.
Now that I have a Yaesu FT-897D
radio for portable operation, I have had to rethink powering TNC's in a
portable environment. Unfortunately the Yaesu doesn't offer the option of using
the internal batteries for powering external TNC's except through the CAT port
which is being used to power the dedicated tuner.
All of the TNC's that I
own have power requirements in the 200-300 mA range at 10-20V except during
firmware updates where power requirements can get up to 500 mA, but that is the
exception rather than the rule.
I am trying to minimize
the size and weight of batteries for my portable station, so the idea of
lugging around a 40 AH wet cell doesn't sit well with me, and that much energy
is a bit over the top for the project.
I have formed two solutions
to this problem, each to be used depending on how much bulk I am willing to
carry with me.
For maximum portability,
I have wired two AA cells along with a 9V battery in series. This gives a
nominal 12V and runs my SCS tracker easily due to the low current draw.
While the 9V battery can't be expected to supply much current for long,
it seems to provide enough power for low power use, and is a very light
package. I did try this with the DR-7800 modem, but the Dragon's thirst
was a bit much for this power supply since this modem needs 300-400 mA to
operate and the loaded voltage out of the battery pack was 6 V, too low to run
the modem.
To handle the increased
load of the Pactor modems, I went to step two, a 7 AH wet cell housed in my
Celestron Power Tank. This device is a
portable light and power supply that has a small flashlight, a 800,000 candle
power spot light, two 10V/10A cigarette lighter plugs, 3, 6 or 9V/1A coax plugs,
and posts that come directly out of the battery for high loads. I ran 12G wire with rig lugs from the posts
to supply a RigRunner 4005 which supplies up to 5 outlets using Anderson
PowerPoles for connectors. This supply will have enough power to run the TNC's and my portable antenna coils for a prolonged time. This configuration also
allows me to have some lighting, run my HT’s through the mobile cigarette power
supplies.
Power to the HF rig is
still supplied by the internal batteries, but the 7 AH battery has enough
energy to supply the designed load for as long as the rig batteries will last
in a package that is still reasonable to carry.
Hi Jeremy,
ReplyDeleteMy comments seem to disappear, but that is due to Google's logon system. This time I won't dwell: why not use a LiFePo4 battery pack of around 10 Ah @ 13.2V (4 cells). They can deliver quite a wallop (30C no exception) and have enough stamina for the less current intensive applications due to relatively low internal resistance. The only drawback: an intelligent, LFP capable charger - but these are afforable and can charge from LFP to NiMH and Pb easily. For /P or /MM (qrp) I use a FT-817 with an external 4200 mAh 13.2 LFP - a qso-saver :-)
Cheers,
Michel PE1MR