I am relatively new to ham radio. I am wanting to build a base station
in my bonus room and use some mobile radios up there.

Is it feasible to build my own power supply? I know one radio requires
13.8 volts and a minimum of 12 amps. I would like to use more than one
radio though.

What about buying one of those cheap emergency jump start pwer cells
you can keep in your car. Could I just use one of those and keep it
plugged into the wall charging at all times?

I like the idea of building one but not sure if it would cost more that
way or not. What would I need to build one besides a transformer and
rectifier?

wrote:
I am relatively new to ham radio. I am wanting to build a base station
in my bonus room and use some mobile radios up there.

snip

I like the idea of building one but not sure if it would cost more that
way or not. What would I need to build one besides a transformer and
rectifier?

Welcome to the ranks; an excellent reference is the ARRL handbook. Your
local library should have a copy or copies.

Quick answer to your question: in addition to transformer and rectifier,
you'll need a safe enclosure, overload protection, voltage regulation
and filtering.

These days, though, it will probably cost you more to build one, unless
you have a well-stocked junk box. Didn't used to be that way.
--
John Miller
email address: domain, n4vu.com; username, jsm
Surplus (FSoT):
New Conn V1 double trumpet case, no logo
Tektronix 465B oscilloscope
New leather business case

I would buy one instead of building it.It would be cheaper.

Jacques

John Miller writes:

wrote:
I am relatively new to ham radio. I am wanting to build a base station
in my bonus room and use some mobile radios up there.

snip

I like the idea of building one but not sure if it would cost more that
way or not. What would I need to build one besides a transformer and
rectifier?

Welcome to the ranks; an excellent reference is the ARRL handbook.
Your local library should have a copy or copies.

Quick answer to your question: in addition to transformer and
rectifier, you'll need a safe enclosure, overload protection, voltage
regulation and filtering.

These days, though, it will probably cost you more to build one,
unless you have a well-stocked junk box. Didn't used to be that way.

Alternatives: PC power supply (you may need a load on the +5 VDC line for
the +12 VDC to be properly regulated) and eBay (always many good power
supplies available).

Building one is certainly an option and a good education experience
which may outweigh the additional cost and effort.

But, maybe not best as a first project, mainly due to the need
for high current regulation but still not out of the question.

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Surplus (FSoT):
New Conn V1 double trumpet case, no logo
Tektronix 465B oscilloscope
New leather business case

I can get a rectofier at radio shack for 5 bucks. I can build the
enclosure out of steel and weld it togther myself.

I need soemone to explain how the circuitry works for a newbie like me.
For instances, what does a transformer do? I mean why couldnt you just
wire directly into the rectofier?

Could I use a household dimmer switch to adjust the amperage?

Could I just use one of those jump start things with a battery inside
them and leave it plugged up? Then it would even work with the power
going out, right?

wrote in message
oups.com...
I can get a rectofier at radio shack for 5 bucks. I can build the
enclosure out of steel and weld it togther myself.

That's only the beginning...


I need soemone to explain how the circuitry works for a newbie like me.
For instances, what does a transformer do? I mean why couldnt you just
wire directly into the rectofier?


Don't even think about doing that, do you want a 12v DC power supply or a
170v DC power supply?

Could I use a household dimmer switch to adjust the amperage?


No, dimmer switches don't adjust amperage, and even if they did that's not
what you need to do.

Could I just use one of those jump start things with a battery inside
them and leave it plugged up? Then it would even work with the power
going out, right?


Perhaps, but I'm not sure how long the battery would last, they're really
designed for intermittent use.

You've got a lot of homework to do before you attempt to build a power
supply, all the information you seek is readily available online. Unless you
can find an old car battery charger to salvage one from, the transformer
will be the most expensive part by far. I would just use an old PC power
supply personally.

wrote:
I can get a rectofier at radio shack for 5 bucks. I can build the
enclosure out of steel and weld it togther myself.

I need soemone to explain how the circuitry works for a newbie like me.
For instances, what does a transformer do? I mean why couldnt you just
wire directly into the rectofier?

Could I use a household dimmer switch to adjust the amperage?

Could I just use one of those jump start things with a battery inside
them and leave it plugged up? Then it would even work with the power
going out, right?

Go out and buy a ready-made power supply before you kill yourself.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

wrote in message
ups.com...
| I am relatively new to ham radio. I am wanting to build a base station
| in my bonus room and use some mobile radios up there.
|
| Is it feasible to build my own power supply? I know one radio requires
| 13.8 volts and a minimum of 12 amps. I would like to use more than one
| radio though.
|
| What about buying one of those cheap emergency jump start pwer cells
| you can keep in your car. Could I just use one of those and keep it
| plugged into the wall charging at all times?
|
| I like the idea of building one but not sure if it would cost more that
| way or not. What would I need to build one besides a transformer and
| rectifier?

Ham radio or CB radio? Which license do you have?

A Google for "build your own power supply" got 155 hits.

N

wrote:
I am relatively new to ham radio. I am wanting to build a base station
in my bonus room and use some mobile radios up there.

Is it feasible to build my own power supply? I know one radio requires
13.8 volts and a minimum of 12 amps. I would like to use more than one
radio though.

What about buying one of those cheap emergency jump start pwer cells
you can keep in your car. Could I just use one of those and keep it
plugged into the wall charging at all times?

I like the idea of building one but not sure if it would cost more that
way or not. What would I need to build one besides a transformer and
rectifier?


Some people use a car battery with trickle charger on it all the time.
But there are issues with caustic vapor in the shack.

If you build a power supply, put your primary attention on over-voltage
protection. If something goes wrong, a semiconductor shorts and puts
WAY too much voltage on your raido. The semiconductor spec issues
that are CRITICAL in this type of application are the least understood
by newbies...and engineers too. If it's a linear supply, you'll need
SEVERAL TIMES as many
pass transistors (properly current shared) than you'd think from the
dissipation ratings. Do some research on secondary breakdown or SOA.

Evaluate the finished product with transient loads as well as fixed
loads in various stages of current limit. Make sure you have enough
oscilloscope bandwidth to see those 100MHz oscillations and big
transient spikes.

"Well, I saved $50 on a power supply and blew up two $1000 radios."
Don't let this be you. Keep an eye out for a used Astron...and test it
thoroughly before you hook it to your radio. Put a request on
rec.radio.swap.
Make your
high current radio supply your third or fourth power supply design project.
mike

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You did say that you are a New Ham..Best do a bit of reading
If you dont you some will be an SK.

kip

Somewhere between the AC input and DC output must be an
transformer. This is essential to human safety. Radio Shack
often sells paperbacks that explain how this is built. You
need to read these books with schematics, part numbers, and
cautions - such as the needed transformer. Way too much to
explain here. But those books make quick reading.

Power supplies in kit form are so simple. But first you
need to read - to learn about the simple mistakes that can
kill.

wrote:
I can get a rectofier at radio shack for 5 bucks. I can build the
enclosure out of steel and weld it togther myself.

I need soemone to explain how the circuitry works for a newbie like me.
For instances, what does a transformer do? I mean why couldnt you just
wire directly into the rectofier?

Could I use a household dimmer switch to adjust the amperage?

Could I just use one of those jump start things with a battery inside
them and leave it plugged up? Then it would even work with the power
going out, right?

I can get a rectofier at radio shack for 5 bucks. I can build the
enclosure out of steel and weld it togther myself.

I need soemone to explain how the circuitry works for a newbie like me.
For instances, what does a transformer do? I mean why couldnt you just
wire directly into the rectofier?

Stryped-

You certainly have the right attitude. Yes, all the answers can be found here
or elsewhere on the web, but there is also a lot of misinformation along with
the warnings about killing yourself!

The best suggestion so far, has been to look for a copy of the ARRL Handbook.
Your local library should have other resources as well.

You should be aware that rectified DC across the filter capacitor may be close
to one and a half times the transformer's AC voltage. If you don't understand
this, then you need to look it up in the Handbook.

The suggestion to modify a computer power supply may be a good one. I recall
seeing an article on how to do that, but don't remember where. You might
search for it with Google.

As a learning experience, you might try a simple power supply with no
regulator. If you could obtain a transformer that would supply the right
voltage at sufficiently high current, you could rectify it and filter the DC
with a large computer-type capacitor. If the output voltage doesn't exceed
about 14 volts DC with nothing connected to it, there might still be about 12
volts under load. If not, then try a bigger capacitor!


73, Fred, K4DII