wrote in message
oups.com...
I wouldn't hesitate to buytheon you mention. But I don'tknow what
your electronic skills are. It could be a very good deal, or a boat
anchor.

Take a look at the diagram in the 2nd link and decide if you could
rebuild one. The transformer, caps, and heatsink are the expensive
parts. If you have those repair is easy and fairly inexpensive.

But there is something to be said for a brand new, and under warrenty
item.

Terry


How good are the Pyramid PSU's??

Lucky

I have seen people use them but an Astron is much better. Also,
If you look around on ebay and QTH.com and QRZ.com you can usually
find a 20 amp for around $40 - $80 , with or without meters, in good
working order.
20 amp might be over kill for you now but it will last forever! Even an
Astron 12 amp would be OK for receivers.
These supplies will run forever without a light receiver load. I have
an astron 50 amp supply that has been on since 1985!!!!!
Remember, you only want to buy a supply one time. If the one you get
is just enough
for your needs today, what happens when you get a few more pieces next
year and now your supply is
too small?
Have fun!!!
================================================== =====

Lucky wrote:

How good are the Pyramid PSU's??


wrote in message
roups.com...


I wouldn't hesitate to buytheon you mention. But I don'tknow what
your electronic skills are. It could be a very good deal, or a boat
anchor.

Take a look at the diagram in the 2nd link and decide if you could
rebuild one. The transformer, caps, and heatsink are the expensive
parts. If you have those repair is easy and fairly inexpensive.

But there is something to be said for a brand new, and under warrenty
item.

Terry




How good are the Pyramid PSU's??

Lucky

"Gen. Geroge Hammond" wrote in message ...
I have seen people use them but an Astron is much better. Also,
If you look around on ebay and QTH.com and QRZ.com you can usually
find a 20 amp for around $40 - $80 , with or without meters, in good working order.
20 amp might be over kill for you now but it will last forever! Even an Astron 12 amp would be OK for receivers.
These supplies will run forever without a light receiver load. I have an astron 50 amp supply that has been on since 1985!!!!!
Remember, you only want to buy a supply one time. If the one you get is just enough
for your needs today, what happens when you get a few more pieces next year and now your supply is
too small?
Have fun!!!
================================================== =====

Lucky wrote:


How good are the Pyramid PSU's??

wrote in message
oups.com...
I wouldn't hesitate to buytheon you mention. But I don'tknow what
your electronic skills are. It could be a very good deal, or a boat
anchor.

Take a look at the diagram in the 2nd link and decide if you could
rebuild one. The transformer, caps, and heatsink are the expensive
parts. If you have those repair is easy and fairly inexpensive.

But there is something to be said for a brand new, and under warrenty
item.

Terry


How good are the Pyramid PSU's??

Lucky


So I'm to assume the more amps you have, the longer the PSU will last??ThanksLucky

POS
I have seen several and even the linear ones are way too noisy.
Go with an aston.
Even a returned unit could ber a very good deal.
Lot's of items are returned that have no problem

I wouldn't hesitate to go for a factory refurbished supply.
If you can afford it, spring for meters. It is nice to be able
to look at the voltage adn currentmeters every now and
then just to check that things are normal.

I had an old Clegg rock bound 2 mtr rig that started drawing
about 2 amps on squelched receive. The amp meter showed
me an unexpected load, so I was able to catch a minor problem
before it became a big one.

Terry

wrote in message
oups.com...
POS
I have seen several and even the linear ones are way too noisy.
Go with an aston.
Even a returned unit could ber a very good deal.
Lot's of items are returned that have no problem

I wouldn't hesitate to go for a factory refurbished supply.
If you can afford it, spring for meters. It is nice to be able
to look at the voltage adn currentmeters every now and
then just to check that things are normal.

I had an old Clegg rock bound 2 mtr rig that started drawing
about 2 amps on squelched receive. The amp meter showed
me an unexpected load, so I was able to catch a minor problem
before it became a big one.

Terry


OK thanks for the heads up. Some reviews were good but they are too cheap
and I never heard of them either.

Well I cancelled the refurbished one. I'm not paying $58 {shipping and
taxes} included for a fixed one. In that case I take a chance on Ebay for
much less.

Heck an Astron RS-10A went for $22 yesterday. OK this is the story I hear on
looking for newer Astrons. It seems if the power cord is able to be
disconnected from the PSU, it is a newer one. They went in this order from
older to newer.

1] oldest is the PSU's with undetachable power cords with the fuse built
into the radios circuitry. You can't see the fuse or access it unless you
open up the radio.

2] PSU's with undetachable power cords with a screw in type fuse seen on
back of unit.

3] The newest is the power cord is detachable and the small glass fuse is in
back of the radio but it's in the radios powercords receptacle. If you can
get a closeup of the powercords jack, you will see a tiny picture of a fuse
right above the jack. It can be changed from the outside.

One with meters is not a bad idea. I'm still looking. I see an Astron with
no crowbar protection but it has a screw in type fuse and I woud be using a
surge protector anyhow. I read the worst that can happen with no crowbar
OVP, is that the full output voltage can occur during a short.

So it doesn't seem too bad if you have a
a PSU that's maximum output is 15v and you don't have crowbar OVP. The most
your receiver can get hit with is 15v if I am right in my interpretation of
the crowbar protection failing. It does have a fuse that will blow from any
heavy surges.

What do you think? Crowbar that important if you have a fuse??

Lucky

Most linear supplis have about +20V before the "pass element",
transistors.

And if a transistor shorts C to E, then ~+20V will appear at the
+12V output. A good OVP/crowbar is a must have!

But if an otherwise good supply lacks an OVP I would add my own.
The first link I gave has a diagram for a very good, in fact better
then
any I have ever seen built iinto any PS. The Areotech diagram specs 1%
resisitors. I used 5% with no decrease in functionality. Given the
orignal
use was to be in aircraft, the slight performance edge offered by 1%
ressitors was well worth it, that is a "life critical" mission. While I
value
my radios, I am more then willking to settle for a little less absolute
performance. I built the first one with teh specified 1% resisitors,
I built another unit with 5% resisitors, and as far as I can measure,
they both trip in about ~50mS. That is 0.05S. Thats for a jump of
13.69V
to +20V.

I use 13.69V because that is the most commonly suggested voltage to
keep lead acid gell cells "float charged". I added a 120V AC relay to
lift,
open, the + output from the PS so during power failures, my radios
keep running.

And as a rule, the larger a supply, the cooler it runs, and cool
equates
to LONG life.

Terry

wrote in message
ups.com...
Most linear supplis have about +20V before the "pass element",
transistors.

And if a transistor shorts C to E, then ~+20V will appear at the
+12V output. A good OVP/crowbar is a must have!

But if an otherwise good supply lacks an OVP I would add my own.
The first link I gave has a diagram for a very good, in fact better
then
any I have ever seen built iinto any PS. The Areotech diagram specs 1%
resisitors. I used 5% with no decrease in functionality. Given the
orignal
use was to be in aircraft, the slight performance edge offered by 1%
ressitors was well worth it, that is a "life critical" mission. While I
value
my radios, I am more then willking to settle for a little less absolute
performance. I built the first one with teh specified 1% resisitors,
I built another unit with 5% resisitors, and as far as I can measure,
they both trip in about ~50mS. That is 0.05S. Thats for a jump of
13.69V
to +20V.

I use 13.69V because that is the most commonly suggested voltage to
keep lead acid gell cells "float charged". I added a 120V AC relay to
lift,
open, the + output from the PS so during power failures, my radios
keep running.

And as a rule, the larger a supply, the cooler it runs, and cool
equates
to LONG life.

Terry


Ok I see. I'm good with my hands, can build a computer with ease, have done
lots of soldering, but when it comes to mission critical items like a PSU
that could end the life of one of my radios or cause a fire, I don't trust
in myself enough to do it. But, I learn very quickly. If I were to be there
with you, and watch you do it once, I could repeat it.

Funny how all these wall worts we use for our radios have none of these
features or protection. Or even are regulated. But, it's very important to
know. Using a simple Radio Shack regulated PSU got rid of the hum that was
driving me batty on my HF-150.

BTW, linear = regulated correct?

Lucky

Wall warts can only deliver so many ma, or for big ones an amp or 2.
A real power supply can deliver well over it's rated current for a few
seconds.

Long enough to turn most radios into slag.

Go with one with a built in OVP/crowbar and try building an
out board one later. In a extened power outage you might find it
usefull to be able to draw power from you car or truck. At that
time you really want to have a OVP/crowbar between your radios
and vehical's electrical system.

Flexiblility is important.

You might want to contact the alarm companies in your area as many
of the better ones retire perfectly good gell cells from alarm systems
for insurance reasons. Having a burgler alarm fall during a powqer
outage because a 3 year old gell cell died is real bad for business.

I have several gell cells that are 10 years old and going strong.
After overcharging them, heat is the biggest killer, keep them cool,
under ~90F, and they will last for years. Here in central Kentucky
we often have nasty T-storms that knock the power out for several
hours. It is very nice to be able to listen to my radios after the
storm
moves out. It is true that I mainly listen to my scanners, but having
a SW is very nice also.

One winter's night 2 years ago the lights went out and stayed out for
about 5 hours. Perfect listening conditions. No nearby TV,s PCs etc.
Very RF quite. Made the extra effort for the gell cells worth while.

Terry

wrote in message
oups.com...
Wall warts can only deliver so many ma, or for big ones an amp or 2.
A real power supply can deliver well over it's rated current for a few
seconds.

Long enough to turn most radios into slag.

Go with one with a built in OVP/crowbar and try building an
out board one later. In a extened power outage you might find it
usefull to be able to draw power from you car or truck. At that
time you really want to have a OVP/crowbar between your radios
and vehical's electrical system.

Flexiblility is important.

You might want to contact the alarm companies in your area as many
of the better ones retire perfectly good gell cells from alarm systems
for insurance reasons. Having a burgler alarm fall during a powqer
outage because a 3 year old gell cell died is real bad for business.

I have several gell cells that are 10 years old and going strong.
After overcharging them, heat is the biggest killer, keep them cool,
under ~90F, and they will last for years. Here in central Kentucky
we often have nasty T-storms that knock the power out for several
hours. It is very nice to be able to listen to my radios after the
storm
moves out. It is true that I mainly listen to my scanners, but having
a SW is very nice also.

One winter's night 2 years ago the lights went out and stayed out for
about 5 hours. Perfect listening conditions. No nearby TV,s PCs etc.
Very RF quite. Made the extra effort for the gell cells worth while.

Terry


Wouldn't the gel cell need to be 12 to 13.8v though? I've heard you guys
talk about gel cells for outdoor radio use. They sound interesting. So you
just add the correct sized plug to the gel cell for your radios power input
jack and you're good to go?

Lucky