Power supply advice.

Currently I run a CRT ss 9900 mobile that I think draws 12amp full power.
I also have for homebase.
Ranger 2950dx        7amp.
CRT ss 3900           10amp ???.

I have two amps to use, 
CTE 767, 80w ?       15amp ???
KL RM 405 V            22amp.

My two main power supplies are.

Manson                     25amp.
Astron.                       20amp.


I'm only going to put around 4watts max into the amps and since the 405 has variable power I'll run that at around half power. And a low pass filter.



I'm wondering about the best setups.

Is it better to individually run from separate supplies or does it not matter as long as they are within the power supplies limits ?

I realise i want to keep below the psu limits.
Ie 20watt max on a 25watt psu.

But interested in what advice and what others setups are regarding this.

 For instance, my setup away is the Ranger and large Manson PSU, there's limited space so I want to use the smaller Astron PSU but then I couldn't run an amplifier too.
I am wondering whether to just get a 50watt PSU if it is ok to run amp and rig together.
Thanks.

Thinking about it I suppose I could run the Ranger and CTE through the 25amp PSU.
Ranger on low power say 2-3 watt and CTE 15, so around 18 watt whilst away during summer.

Winter at home, either ranger or 3900 on Antron PSU and RM amp on 25watt PSU.

If it's ok to run rig and amp from one supply or better off separate.

In the past i have ran both from one psu.
Nowadays i run my HF set's one at a time and when cold i run my diesel heater all from one psu.
It is a Palstar sps-9600 60amp.

Hi Nige,

It's all too easy to overthink these kind of things and get wrapped up in numbers....usually for good reason as you don't want to blow anything up!

Remember that when using SSB modes your vocal power will average 10-20% of PEP (Peak Envelope Power) so your current draw will not be as excessive as you first think. CW, FM and digital modes draw the most current. (Although heavy voice processing can make your SSB vocal average 50% or so!)

Certain sources of 'wisdom' will suggest you run separate power supplies for linears and rig but there is no problem running them all from one power supply so long as it can provide sufficient power. (You only have to think about Ham Radio equipment that kick out 100W or so.....it's all in one box but still separate circuits for the PA.)

Issues arise also when you start thinking about 'ground loops', 'RFI' problems, etc. let alone 'failure modes' of power supplies.

A linear power supply (unless containing some sort of 'crowbar' or protection circuitry) can kick out the full rectified transformer voltage under failure conditions. A typical 20 odd to 30 volts or so from that will certainly destroy anything connected to it! Switch mode power supplies on the other hand tend to give out no voltage whatsoever when they fail. Despite horror stories of 320 volt DC or so (from rectified mains AC) inside them the isolation runs to thousands of volts so flash over opportunities are slim to none.

'Ground loops' are a whole subject to themself pontificated endlessly on typical 80m 'rag chews'. Solving any RFI problems first usually resolve such issues and often 'solutions' to grounding problems arise to actually creating ground loops!


None of this is helping much or is it?

Nige, much as I wouldn't trust anyone to tell me that the missing wheel nut on my car wheel will be OK so long as I keep it under '30' I wouldn't trust running power supplies with things 'turned' or 'wound' down.

The answer may simply lay in your own thoughts of a bigger power supply...and I mean 'bigger' as in current capability. My own 30 amp switched mode power supply is a fraction of the size of my old 25 amp linear one and even 50 amp units are smaller and more affordable than the equivalent in copper & iron laminates of a linear or transformer type.


Anyway, a bit of my 'waffle' but I hope you get something sorted out.  

All the best,
Victor

Nice to see your "Waffle" again Victor.

Thanks Alan and Victor.
Yes Victor, that bloody FM soon flattens my car battery if I forget to turn the power down after SSB
Apparently the Manson PSU has malfunction protection (and I love the old hum as you fire it up )

And apologies, the other is an Astron PSU not antron and is switch mode
Do you get much noise interference with the switch modes ?

I will probably just buy myself a Sharmans 50amp switch mode for Christmas

My 60amp is switch mode and no noise at all from it.
You get what you pay for i think.
The one i have i bought second hand but still cost me £110 could have been £120 but the new price was eye watering.
They do come up for sale on the bay now and again mine is Palstar SPS-9600 but you do get them with other names but still model sps-9600.
Did see one last week.
There is a picture in my shack build thread and it is still in the same place and never been turned off 14 months now lol.

Nige, is the Manson the EP-925?

Only because the 'malfunction protection' is a simple thermal current limiting switch in them. When they fault they can kick out some 22 to 24 volts!!

The old Astron linear units do have crowbar protection circuitry in them (or did when I last looked) but can still pop out 15 volts before that circuitry kicks in. That's only if the regulator chip is fully functioning though and the correct rated fuse is installed otherwise you can get 18 volts upwards out of them with a fault.

The above can and usually do occur when subjected to heavy current loads. (Which is what you're trying to avoid!)


If you have the more modern Astron switch mode unit (as mentioned?) then you already have experience of switch mode technology in as far as any interference possibilities.


Switch mode power supplies when correctly designed produce no RF emissions (as Alan has already stated).
I have the Sharman SM-30 which has served me well and was a fortunate gift after a Ham friend upgraded to the SM-50. I've seen people 'bodge' up cheap lighting switch mode power supplies but there is no guarantee that the appropriate RF filtering components or good design are placed in them. Again as Alan states, "you get what you pay for".

Your future plans for an SM-50 or similar should serve you well.


I know what you mean with the 'hum' of old linear power supplies though - my old unit was so big it sat under the bench and I used to prop my feet up on it to keep them warm!

Just had a laugh.
Looked on the bay and R.T.I want £300 for a second hand one like mine.
They over price everything but i don't think they will sell that lol.

Victor wrote:

Nige, is the Manson the EP-925?

Only because the 'malfunction protection' is a simple thermal current limiting switch in them. When they fault they can kick out some 22 to 24 volts!!

The old Astron linear units do have crowbar protection circuitry in them (or did when I last looked) but can still pop out 15 volts before that circuitry kicks in. That's only if the regulator chip is fully functioning though and the correct rated fuse is installed otherwise you can get 18 volts upwards out of them with a fault.

The above can and usually do occur when subjected to heavy current loads. (Which is what you're trying to avoid!)


If you have the more modern Astron switch mode unit (as mentioned?) then you already have experience of switch mode technology in as far as any interference possibilities.


Switch mode power supplies when correctly designed produce no RF emissions (as Alan has already stated).
I have the Sharman SM-30 which has served me well and was a fortunate gift after a Ham friend upgraded to the SM-50. I've seen people 'bodge' up cheap lighting switch mode power supplies but there is no guarantee that the appropriate RF filtering components or good design are placed in them. Again as Alan states, "you get what you pay for".

Your future plans for an SM-50 or similar should serve you well.


I know what you mean with the 'hum' of old linear power supplies though - my old unit was so big it sat under the bench and I used to prop my feet up on it to keep them warm!

Yes it's an EP-925 Victor.
And an Astron ss-45.

I take it there's just a surge in volts then that damages the rig/amp components and no short to blow the inline fuses ?

Yes I'll definitely keep the current draw down on them now
Thanks.

Alan Pilot wrote:

Just had a laugh.
Looked on the bay and R.T.I want £300 for a second hand one like mine.
They over price everything but i don't think they will sell that lol.

Seems the norm to ask extortionate prices on fleabay lately .

Saw a 40 channel 27/81 homebase CB for HF radio money on there a while back

Great stuff we like a bit of waffle it helps the day go round thanks Victor 

This is the 40amp version of the one i use and not a bad price.
SPS-9400

Alan Pilot wrote:

This is the 40amp version of the one i use and not a bad price.
SPS-9400

Stop it Alan I've just spent more money on radio gear

No noise of my one lol.

Are these Sharmans, palstar, Maas etc all the same since I see most using the same casings under different brands. ?

I think they are the same.
As you say the numbers are alike and the shape of the front.
It finishes later ??????? lol.

i have just sold my 7 amp transformer on fleabay today happy days 

Alan Pilot wrote:

I think they are the same.
As you say the numbers are alike and the shape of the front.
It finishes later ??????? lol.

Haha, bought

Here's a talking point.

https://youtu.be/Ufu0FHXozaU

What should be the power output be on his 6900.
I thought it was about 40w so i just put my dummy load on my 991a to test.
40w is pulling 12.1w according to my test.

Good point Alan. Don't think the video mentioned the output power of the 6900, but as you may know they have come with various output powers over their production life and also varies with how they are setup (export or not). 40W is the highest I have seen quoted for these, that's what mine does on FM, but some only do 12W. SSB seems to vary between 12W and 35W.

quoted from Knights website.

                       -------------

"As a rough guide to the size of power supply you will need:

3A = 5W,  5A = 30W,  8A = 60W,  10A = 100W,  30A = 200W"

                        ------------


A CRT 9900 claims 50w FM and 60w SSB although I've heard claims of 100w.
The maximum drain on TX is stated as 12A.

This is why I'm going overkill on PSU's

Just put me off buying from them then.
A 1k+ HF set running on a 10a psu not me.
30a would be the boy for that job in my opinion but that's just me ??? or is it ?.

Alan Pilot wrote:

Just put me off buying from them then.
A 1k+ HF set running on a 10a psu not me.
30a would be the boy for that job in my opinion but that's just me ??? or is it ?.

Well that's not going to put me off buying from Knights as I've only experienced decent  service from there

I should be plenty covered now.
Manson 25A linear runs the cheap CTE amp with a 15w draw.

Astron 25A switch mode runs the Ranger with a 7w draw.



Sharmans 40A switch mode should arrive tomorrow