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Reviews For: Watson W-25AM

Category: Power Supplies

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Review Summary For : Watson W-25AM
Reviews: 11MSRP: 92.25 (£)
25Amp (30Amp peak) 0-15v dual meter power supply
Product is in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
G8DYK Rating: 2013-11-30
Good but could be Dangerous! Time Owned: more than 12 months.
Good linear power supply and yes the fan is a bit noisy but personally that's not the problem.
When new the PSU was great, but after about 12 months mine (and a few others according to the internet reports) developed a fault with the front panel voltage control pot. Ever so slowly, the voltage on mine was rising but fortunately I spotted it before my expensive transceiver was toasted.......
There is over current but no overvoltage protection on this and also the similar W-30AM so beware.
G0AFQ Rating: 2012-11-26
A good and solid performer Time Owned: more than 12 months.
I've had this power supply now for several years, but it's audible noise both from the cooling fan and the growl/buzz from the cabinet has always been a nuisance, so I moved on to a Switch Mode Power Supply which was as quiet as the grave, but in RF terms was very noisy. So back to the Watson, changing the fan to a silent version helped a great deal, then adding 3 diodes in series with the fan thereby reducing the feed voltage to 12 V quietened things even more.

The cabinet is made of mild steel (I think) and is therefore very prone to magnetostriction effects, and what does the cabinet sit very close to…a large mains transformer. Now then, when you cause the power supply to work hard, or even not so hard, the transformer throws out a considerable electromagnetic field which in the UK is at 50 Hz, and in the USA 60 Hz. The cabinet rattles along at this frequency causing a horrible growling buzz. The answer is to use a piece of 1 mm sheet aluminium to fabricate a replacement cover, I have no mechanical expertise whatsoever but found this very easy to do, the only tricky bit was drilling the fixing screw holes in the right place. Now my Watson power supply is not only electrically quiet but mechanically quiet also. Well worth the $3 that the aluminium cost me.
CR7000 Rating: 2012-08-20
Great If You Do The Fan Mod Time Owned: more than 12 months.
This is a well built linear power supply ( I am not a great fan of switch modes ) so for me linear it must be.

Out of the box, nice build quality, performs exactly as it should, nice stable voltage, good so far.

Now the fan, If the power supply detects the slightest amount of current being drawn then the fan goes on full blast, jet engine style.

Every time you key up then you get the turbo fan, which does not go well with your transmitted audio.

You can hide it under a desk, or in a cupboard, doesnt matter you will not stop the fan noise being transmitted along with your voice.

The fix, is to buy a silent 80mm fan and replace the standard one, good results with a 20db fan, runs near silent, then you can throw the noisy fan away, job done.

I picked up a silent 80mm fan from my local maplin, its an easy change for competant people, and the fan cost me £5.99.

Ok so you should not really have to mod a power supply that is brand new, but have you actually found a new quiet one ? I certainly havent.

So it gets a 4 from me, purely because it needs a silent fan installing, why they do not fit these in the factory is beyond me, maybe cost.

Once the fan is changed then its a real top performer, its even quiet enough to sit there on the desktop and not be heard, and the build quality will surely last for years.
M0HQW Rating: 2011-08-15
Very buzzy! Time Owned: 0 to 3 months.
This power supply is very rugged and looks built to last but unlike the other reviews I don't have a problem with fan noise as much as a very loud buzzing noise; If I leave the power supply on with no load on it at all for around five minutes it will start to buzz and gets progressivly louder. Then the fan kicks in...
GM4WCE Rating: 2011-04-06
Noisy! Time Owned: 6 to 12 months.
Just like the last comment - this PSU is REALLY noisy. As soon as you touch the key, even after just a "dit", the fan kicks in at full speed and remains this way for a few minutes. The noise is really loud. Although the PSU is well built and seems robust this is a real pain and I would not buy this again. I have modified mine now and it is much quieter, but bear this in mind if you are considering this unit.
MM0RKT Rating: 2010-10-11
Needs modifications Time Owned: 0 to 3 months.
I bought this on EBay after my Alinco switch-mode PSU packed in.

I was astonished how noisy it was. The fan comes on as soon as you hit the PTT and not when the temperature of the heatsink starts to rise. So I opened it up and had a look around.

a) the heatsink is a hollow aluminium block with the fan at one end. There's what looks like a heat sensor bolted to the heatsink at the fan end
b) the fan is a cheap-looking 80mm 12-volt computer case fan
c) the fan runs at the operating voltage, which in my case is 13.8 volts - no wonder it's noisy! My guess is that it's running above its operating voltage and won't last too long.

Here's my modifications

1) cheap and easy: drop the fan voltage to around 10 volts with a 27 ohm 1 watt resistor. You'll see the two wires from the fan: one goes to ground on the bridge rectifier block and the other to the fan control board
2) awkward: change the fan to a low-noise 80mm fan. Mine is a 21dB one which I had in the junk box. You need to unbolt the heatsink and twist it round so you can get at the four screws which hold the heatsink. You don't need to unsolder any of the wires, but it is quite tricky to get at all the screws holding the fan to the heatsink. has details on how to change the capacitor on the fan control board to a smaller value one which will cut down the time the fan is on. I didn't bother because my new setup is very quiet.

A word of warning. If you run this power supply flat out, then it's probably best not to do the voltage modification or, at best, drop the voltage to 12V.

It's now a very quiet unit. It has all the outputs I need plus the two meters. Because of the noisy fan before modifications, I give it a 4.
2E0TZM Rating: 2009-10-26
Spot On Time Owned: 3 to 6 months.
Had mine for about 6 months now and has been very relible but was a little noisy fan wise had to keep it under the desk, but changed the fan to a little slower one designed for a pc and now silent and no extra heat generated.
M0OXD Rating: 2009-05-08
Sturdy, reliable...and very noisy Time Owned: 0 to 3 months.
Sturdy, reliable...and very noisy. What's more to say. You get a regulated instead of a switching psu so that no spykes and interference from the latter will affect your hamradio experience. Instead you get qrn from the loud fan of the W-25AM. Well, I guess will keep it as far from the rig as possible.
M3SVO Rating: 2008-01-01
GREAT Time Owned: more than 12 months.
I've owned my W-25am for about 5 years now and leave it turned on permanatly. In the past it has powered large car stereos and amps and many HF radios without any problem.

The fan is very noisy and the slightest jump in current sets it going for a good 5 mins, although I found that both the FT-817 and IC-703 don't set it going at all.

My Watson's been going for 5 years solid and I know it still has many years to give, I will update this review in another five years.

G4ICB Rating: 2007-11-20
Good but noisy Time Owned: more than 12 months.
It's big, it's heavy but it's reliable.
But the fan is so noisy,you need headphones to QSO.