Shack PSU

I’m looking for a PSU for the shack. Initially it will power the FT817ND but I plan to get a 100W HF transceiver in due course so it needs to be able to supply 20A or more. There are plenty of switch mode power supplies available but I worry about whether they produce any interference. There are a few linear PSUs around but they are more expensive, very heavy and less efficient. So what are people using at home? Do you have a switch mode PSU that is clean or can you tell me which ones to avoid?

Microset PTS124. SMPS 13.8V @ 22A continuous, 25A max. No RF noise. 2004 vintage
Revex P300 Linear 13.8V @ 30A 1992 vintage.

The most annoying thing about the Microset is the fan is whiny at low speed and noisy at high speed. Revex fan controller packed in after 15years and I made a new one out of a dual 555 and a BFY51 to make PWM based speed controller.

Thanks, How annoying is the fan on the Microset in practice? Very noticeable or just a background noise?

It’s more penetrating than all the other junk in the shack. But I’ve had it for, what 13yrs?, and I haven’t done anything about it yet.

IMHO, one for the “beware oft” category Richard - Manson EP-925 Linear 13.8V variable@22A continuous. No RF noise.

Switch on and the volts go to 16V before settling - no crowbar fitted. The meter is inaccurate and the variable control a joke. The switch on voltage surge took out the PA transistor in my BNOS 180W 2m linear which cost £40 to replace. The fan is noisy, but like Andy I haven’t done anything about it yet. At least it hasn’t failed me - now 25 years old.

73, Gerald G4OIG

Edit: Servicing the fan certainly helps with the noise, but it is nigh impossible to get all 4 mounting screws back in position as the smoothing capacitor is in the way.

I have used one of these for several years to power all the 12v equipment in the shack:

I have no connection to M0UKD, but his review popped up when I searched for more info before recommending it, and I would agree with his findings.

Mine is the 40A version, with analogue meters, and badged “Lowe”.

Seems well made, no interference, and I don’t find the fan objectionable, but then my hearing is not what it once was ;o)


PS Enjoyed meeting you on Holyhead Mountain recently Richard.

I’ve got a (Maplin badged) version of the one reviewed at:

I’ve had it 4 or 5 years and it’s been happily running all the kit in my shack. It’s got a knob for shifting the switching frequency, but I’ve never found a birdie from the PSU. Like many other designs you can have variable volts or lock it to 13.8v.

The main output terminals are on the back, but the low current ones on the front are useful when experimenting. The fan drones a bit but it’s not objectionable to my ears.

73, Colin G8TMV

I use an nevada radio 40a linear psu. Meters are good and accurate. Thermal regulation is your typical “bang bang” style control loop. Fan noise is inevitable cooling down the classic 2N3055’s

Runs my HB PICaSTAR 150w RF out no bother. The power supply is one of the few items that isn’t home made

Not many linear psus on the market that will deliver that amount of current for larger PAs

Using a “no brand” linear PSU for many many years here, nothing fancy … no meters … no fan … nothing to adjust , and no RF noise. It’s marked as FX-1765.
Don’t know if it is for sale in the UK, only found this lookalike :

Luc - ON7DQ

Hi Richard, using an Alinco 30A max with 25A continuous here, purchased this nearly 2 years ago and have had no problems as of yet. This is really quiet, Maplins do their own version nearly £50 cheaper which our club as purchased and as of yet no problems.

The Maplin one is:

Hope this helps

Those internal photos suggest that this PSU is well built for a consumer item. The internal wiring is neat, and that one has plenty of filtering in place.

I have two PSUs in the shack, one is the Manson EP-925 bought new from Lowe in 1989, and has performed faultlessly ever since, the other is a QJE 30a switched mode PSU from Moonraker, about three years old, no RF noise from either, the fan runs continuously on the QJE, but is very quiet, the fan on the old Manson cuts in and out, when drawing current.

Not sure about and switch mode ones, but for Linear one you might want to consider a PSU with built-in over voltage protection or at least consider adding an over voltage crow-bar circuit to whatever you choose.

I recently had one of the Transistors (2N3055) in a different model 2nd-hand PSU (from a SK family friend) go short circuit (and the other open-circuit) leading to the radio that was connected to it getting around 30V fed to it (the radio shutdown and survived) - that PSU has had replacement transistors fitted and over voltage crow-bar added.

The EP-925 does not appear to have over voltage protection, but does have over-load protection - I keep meaning to add a over voltage crow-bar to mine but I have not done so as yet.

Looks like I am the odd man out because I use a surplus H-P server switching supply. I don’t know what more to ask of it - no RFI at least on the bands I use, solid regulation, adjustable from 11.5 to 13.6 volts, fairly quiet with fan speed controlled by output (40 amps with no drama), short circuit protection. Weighs about 3 kg. Oh - did I forget to say it cost $18 shipped? Steve JS6TMW

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In the end I bought a Nevada PSW-30 switch mode supply. It’s identical to the QJE, Maplin and Moonraker ones mentioned and looks like it came out the same factory as the Alinco. It’s now happily powering an FT450D on HF with the FT817 on 2m. I’m not sure whether or not the fan is running as it is very quiet. I’ve not noticed any switching noise yet either. So very pleased. Thanks for all the advice.

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