[BOMBER]

Hi All,

A question I need answered am about to purchase my first power supply in a very long time have the amperage sorted but what type Switch Mode or Linear have been told Linear as the Switch Mode over time can create a hum or noise through your transmissions any theories on this would be fantastic.

Bomber

[bodyguardnz]

I use a linear here,

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thats the baby

[Commscan]

Hi Bomber,

There are some very good switchmode power supplies out there, and some operators report having no problems with them.

I have always used linear power supplies with nice heavy transformers in them.
Never needed to use a switchmode supply, so I do not have any personal experience using one with radio transceivers.
The issue with switchmode power supplies can arise from the use of Pulse Width Modulation (PWM) or the fast switching of output transistors to provide the voltage and current required to run the connected equipment. In some cases the PWM can appear at the DC output in the form of noise, which can translate to noises generated in the radios receive stages (noise can appear across the HF bands in the form of carriers or hetrodynes) or even on transmit by causing the modulated waveform to be distorted or contain hum.
That could occur in fairly extreme circumstances usually with cheap (therefore poorly regulated or filtered) power supplies.
Some switchmode supplies are equipped with a front panel control to adjust the PWM frequency, which can help to alleviate noise if it becomes an issue.

A poorly regulated linear supply can also exhibit similar problems if too much AC noise is present on the DC output.
Many a CBer will have come across someone trying to use a battery charger or DC model railway supply to run their radio....with pretty disastrous results.

Switchmode supplies have the advantage of being lightweight, tend not to produce much heat and can be very cost effective.
A linear supply is usually pretty heavy (as in the case of a 20A or higher current model) and can get rather hot under load (the transformer especially).

Commscan.

[Vampyre]

I use a switch mode here and it is fine. It is a Manson SPS9600.

[MacMan]

I use a switch mode here and it is fine. It is a Manson SPS9600.

I second that one Vamps, it's a great unit, I've been using one for about 3 years with out issue.

[ozstickman]

I use an old computer power supply turned into a power supply. It supplies 50A. Cheap and easy. Local ham guys here been doing it for years.

[AJ66]

I use a switch mode here and it is fine. It is a Manson SPS9600.

I second that one Vamps, it's a great unit, I've been using one for about 3 years with out issue.

I can't remember where I read it (maybe here?), but the Manson 60amp PSU is touted as pretty much THE best 13.8v SMPSU out there. I was lucky enough to grab one from Radio Parts Group here in Hellbourne a couple of years ago when they had them at $249.00ea. Mine has performed flawlessly for 2 years at 40A - 50A output regularly, especially when playing Moonbounce. There is ZERO identifiable noise from the Manson PSU on 2m or HF.

Having said that, I still have my first ever PSUs that I bought/was given as a kid (both linear), an old Yaesu FP-700 from circa 1984(?) and an even older Dick Smith 2A continous (modified with bigger external heat to increase the continous current rating) from Xmas 1978 or '79. Both have been abused over time and never missed a beat. I certainly wouldn't hammer a SMPSU the same way, but the generally higher current outputs of them means you usually don't have to.

I use an old computer power supply turned into a power supply. It supplies 50A. Cheap and easy. Local ham guys here been doing it for years.

Computer PSUs can be an excellent and cheap way of getting enough current. If you Google it, there are ways of tweaking the output voltage up to 13.8v from the nominal 12v.