Looking for a small amp to hook up on the 11m base.

[tba02]

I'm on the 70 amp train myself.

 

[Captain Kilowatt]

I'm on the 70 amp train myself.

Yup. 500 watts output divided by 13.8 volts is 36.25 amps and assuming around 50% efficiency that would make it 72.5 amps total current draw. It is likely a tad more than 50% efficient so you can assume a 70 amp supply would do it but there would be no headroom. A 50 amp supply won't cut it for full output even without being over driven.

 

[222DBFL]

At least a 70a supply for that amp. More toward 100a would be a safe bet. The more the better. Can't have too many amps, but having not enough amperage is a bad deal.

 

[BBB]

Yes^^ 100 amp DC supply required for base use on a (4) pill Toshiba 2sc2879 amp. This is almost always over looked because of the associated additional cost

You can say " but I run a 40 amp supply and it works well". Believe me, you will never realize the full potential output of the amp and if you're searching for wide band audio "head room/ dynamic range" is half the battle

 

[BBB]

These claimed 100 amp/12.6 VDC @ 220 VAC line voltage converted server blade power supplies have been showing up on eBay for less than $75 but I've never tried one. I am unsure if they produce any hash or noise in the radio receiver. I believe they are limited to around 12-13 VDC and in that case would be suitable for a Ham radio use so as to not over-volt and possibly damage the ham transceivers components:

http://www.ebay.com/itm/AC-TO-DC-12...652165?hash=item4d3ff747c5:g:qKgAAOSwy5ZXB8Ie

 

[222DBFL]

The MegaWatt supplies are another choice as well. 2 50a supplies parallel. They are made this way from the factory and no additional parts needed. Up to 4 I believe can be paralleled. That should give plenty of amperage. Price is $110 each or $220 for 2 new power supplies that have a 2yr warranty. Not a bad deal and they are clean running PS units. Just some food for thought.

 

[tba02]

The ebay item referenced by BBB is an HP common slot power supply. In this case it is a DPS-1200 / DPS-1200fb. They max out at about 13.0 volts (I have one that does 13.2). The fan is quiet and I have not experienced and RF hash.

You can roll your own for less, especially if you don't want the meter.
You can get them for about 30 bucks on Amazon.
The sense-on procedure and voltage output information can be found at - http://www.rchelination.com/setting-hp-dps-1200fb-power-supply
You can skip the 24v stacking section.

There have been some cases where you need an different resistor than listed in the post. The write up uses a 1W, 1000-Ohm metal film resistor. I know a 1/2 watt 390 ohm has been used and helped with flaky startups.It looks like the one on ebay is 470 ohms.

That being said, I would go with two MegaWatt 50 amp units stacked. I wish they had been available when I originally purchased from them. The reason I know about the DPS-1200 is because I salvaged some various units out of old servers and use it for non-radio activities currently.

 

[222DBFL]

I hear that TBA02. I would have gotten the 50a one myself just for the extra amperage. Don't truly need it, but I like having headroom!! Not that the 36a model is shabby in any way to run an HF radio and a couple other things. Just better to have a good amount of headroom and keep the PS cool and not pushing it too hard. My local pal bought one when they first came out and he has been very happy with his. Set under his desk he has no noise issues at all with the fan and it works very well for him. Good units for the money.

 

[rabbiporkchop]

I was thinking 50 amps at a hundred percent efficiency with plenty of Headroom.
..

 

[Road Squawker]

I think a 50 amp power supply should suffice with plenty of Headroom

I was thinking 50 amps at a hundred percent efficiency with plenty of Headroom.
..

HUH???? did someone change the speed of light constant?
(think about it)

 

[tba02]

I think a 50 amp power supply should suffice with plenty of Headroom

I was thinking 50 amps at a hundred percent efficiency with plenty of Headroom.
..

Yeah, I understand what you were saying, and if you are speaking to a 250/350 series two transistor amp then yes. If you are referring to a 500 series four transistor amp then no, I don't believe your suggestion is valid.

CK already provided the math so I won't repeat it.