So, power supplies....

Hi guys, I run a standard CCTV style PSU that kicks out 13.8v and can provide 10amp if needed. It cost me a tenner on Amazon

Genuine cb or ham psu's seem ludicrously expensive for something with half the amp output.

I get great comments about my audio quality and I don't get any noise coming through so why do folk pay hundreds for the proper power supplies??

Am I missing something?

HAM power supplies usually need to be 25-30A for 100w radios, hence will cost more.

Also, they need to be RF quiet on a lot more bands/ranges than just 11m for a CB one.

Really expensive PSU's are often still linear rather than switch mode, and they are much more expensive to produce.

Plus one for what Jeff says there Mike.

I run a Sharman 30 amp switch mode which has the 'noise offset' control on it to prevent any interference or 'birdies' and runs clean as a whistle from LF through to UHF. As it's designed for radio use I know that it shouldn't falter around an RF rich environment too. I actually thought the purchase price was very cheap considering.

I used to have a linear type which weighed a ton with all that steel and copper in the transformer and hence why they're expensive. (It was a right foot-warmer in winter too! )

At least with a switch-mode type I have the reassurance that it's failure-mode is a no-volt scenario but have seen a lot of linear types where once that regulation circuitry fails the full unregulated DC pumps out!!.......Not nice with an expensive Ham rig connected to it!

A lot of people will fork out silly money for linear types believing they're "cleaner" than a switch mode and in the end I suppose it's up to them. I just know that I'd rather pay a bit more money for a power supply if it's going to be hooked up to an expensive to replace HF transceiver.

If your setup is working well for you then all is good, I do like a bargain myself but usually where things are less critical. I have however built my own SWR/PWR meter along with an ATU as the price of that sort of stuff is in my mind ridiculous...and usually not very good either.

Great posting there Mike, always good to discuss such things.


All the best,
Victor

That's good reading, thanks guys.

This is the one I currently use

12V 10A DC Universal Regulated Switching Power Supply Converter, 120W Adapter Transformers for LED Strip Light,Radio, Computer Project,Video Surveillance,Probe Signal Lamp https://amzn.eu/d/fhC6hP9

For the price it's so cheap, what do you think?

She's only little but 10a is more than enough for a crt6900v.  If I get a burner I'll get a bigger one.

It's a pretty generic switch mode power supply that turns up in various similar guises but seems to be used by many as a cheap CB power supply.

It'll easily provide the 10A and probably a bit more with most seeming to have provision for open-loop protection (even if the controller chip inside doesn't) to prevent over voltage conditions which would otherwise have your rig up in smoke.

The thing that concerns me about such 'bargains' is that you are buying blind and in actuality don't know what's going on inside them. Manufacturers looking to make a quick buck will often leave out certain safety or RFI components and you can see why if they save a few cents per unit when they hope to sell hundreds of thousands or even millions of them. (That's a lot of dollars for them and screw you if it goes wrong.)

With more expensive units they are infinitely better designed specifically for the job at hand without cutting any corners for RFI emissions, open-loop, over-voltage or even short circuit protection.

You pays your money and takes your choice really.

I just know that I'd prefer a known reliable brand safe in the knowledge that the extra money invested means I'm not forking out for a replacement rig should anything go wrong.

The Sharman I mentioned has had recorded regulation circuitry faults but never kicks out more than 16 volts at worst with most rigs surviving that.....the cheaper power supplies can kick out six or seven times their voltage which will definitely release all that 'magic smoke' from your rig.



If anyone is interested there is a 'teardown' video of such cheap power supplies on youtube here :-

https://www.youtube.com/watch?v=B19rB_FR5Mk


Worth noting that common mode current or RF feedback can come back from your antenna (especially with higher wattages) through even the 'grounded' braid and without RFI protection in the power supply all sorts of things could happen.

I hope that helps Mike and explains a little about why some CB and especially Amateur Radio power supplies are that much more expensive.


All the best,
Victor

Amazing reply, thanks Victor, I think you're right, you get what you pay for. As I progress my love for radio and my rigs get more expensive I will definitely protect them accordingly with a reputable PSU. 

While I am only fiddling with cb and ssb, mainly the 6900v it's quite a cheap unit for what it does. Not worth spending hundreds on a PSU to protect a cheap radio. When you start spending thousands on the radios and multiple bands I can see it's essential to protect those.

I understand my interpretation of a cheap radio isn't everyone's idea of cheap so apologies if offend anyone here.

Ah, don't apologise preemptively for any offence that may be caused as it's a sure fire way of finding someone that will take offence!

It is after all a fantastic hobby this radio malarkey and people should be free to enjoy it as they see fit. 

I happily run much homemade gear and even an antenna made from an old electric lawnmower cable all to my own satisfaction (working the world) as well as scan about for a bargain or two. In all likelihood you'll probably run that Amazon PSU merrily with your 6900 never experiencing a problem at all and I do hope that is the case.

If anyone should apologise it's me for performing my usual waffle with such subject matter and just one of the many fields of interest that lay within this incredible hobby.

A brilliant posting Mike and very enjoyable to discuss.
(Certainly makes a change from the usual call sign requests who then disappear never to be seen again. )


All the best to you there Mike and keep happy.

Great discussion starter Mike. I have and still use sometimes very cheap PSU options including HP server PSUs, and they have worked well for me.

I "upgraded" (not the best word, just read on) to a used Nissei switch mode PSU which I picked up for almost nothing. I think they are about £90ish if I had bought new. That's nearly 90x the server PSU cost. I didn't notice any noticeable difference in receive noise. It died after a few months, with a very loud bang, and confirm what Victor says about switch modes going to zero voltage as no equipment was harmed, though... I might of needed new underpants. (By the way, I am not downing Nissei PSUs for their performance and reliability, I have no idea how much the one I acquired had been used or anything about its previous life history).

I am currently using a 30a linear PSU. I had the opportunity to change to an option that I thought might reduce the noise a little. Again, there is no noticeable difference to my ears and radio waterfall in the receive noise.

If you or anyone get a good working cheap switch mode PSU then good on you, some work very well as I have proved to myself. Some PSUs do not make good options though like laptop chargers, and the first one I ever tried to use as a kid which was a Hornby model train PSU (linear, but far from smooth output), I transmitted quite a buzz I can tell you.