Author Topic: WATSON W-25AM PSU DECOUPLING PROBLEM  (Read 2673 times)

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Offline g6ypkTopic starter

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WATSON W-25AM PSU DECOUPLING PROBLEM
« on: December 29, 2013, 11:59:28 am »
 :phew: GREETING BROTHERS AND SISTERS, HAMPERS, DOGS, CATS AND GERBILS.
Cap off..
Sorry about that. I'm too tired to turn the caps off and rewrite the line.

To business: I am the not so proud owner of a Watson W-25AM linear PSU. I thank the Gods I also have a Power Max 45NF here too, but have run out of terminal space.

I enjoy working 4 and 6 metres. BUT, and this is the big but; as I have no room left on the Power Max 45, I have had to resort to the W-25A to transmit with the two radios on 4 and 6 metres.

You guessed it: The W-25AM falls down at the slightest sniff of low band RF.

Yes, I know, I must be dumb, but even though I have been a ham for 34 years, I have never had to decouple a PSU before. So, I guess it is about time I learned. A few pointers here and there would be most welcome. That is where to and where not to decouple and what values, etc. I guess I have to get pencil to paper and work out values that are short to 4 and 6 metres, but where on a PSU is the best place to put the capacitors for best effect?
73 de Tony


 

Offline Rerouter

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Re: WATSON W-25AM PSU DECOUPLING PROBLEM
« Reply #1 on: December 29, 2013, 12:36:19 pm »
Sorry i'm not much of a HAM, so i wasnt able to follow all that you said

none the less, I'm going to assume this is just powering the radios, if such then that makes it a lot easier,

the easiest thing you can try is get a ferrite coupling big enough to wrap the power lead through to form a loop atleast once, (positive and negative is ideal) this forms a common mode choke and will reject most RF being injected by the radios,

if no luck there, tell us what exact frequency range you want to use, the noise is likely to be that fundamental or a harmonic, if such we may be able to point out a capacitor value to put in parallel with you output capacitor (to as a very quick test grab something in the order of 1nF ceramic and a 10nF ceramic, and tack them in parallel as close to the connection terminals as possible
 

Offline vk6zgo

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Re: WATSON W-25AM PSU DECOUPLING PROBLEM
« Reply #2 on: December 30, 2013, 05:09:43 am »
Well,the UK 4m Ham band is around 70MHz,& the 6m band around 50MHz,so it is basically low band VHF.

I would agree with Rerouter's comments,but you may have to get inside the beast,& do your bypassing close to the control circuitry.
I would also suggest that you ask this question on QRZ.com,as some of the Hams on that site may have  experience with the same problem.
 


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