[MRCA] 24 volt power supply

Thu Jan 3 16:13:36 EST 2019

I stand corrected, don’t have it in front of me but no matter how far away if you ever had to move a 350K or rack mount one you will never forget how heavy it is!

RF

From: Peter Gottlieb [mailto:kb2vtl at gmail.com]
Sent: Thursday, January 03, 2019 4:10 PM
To: Ray Fantini <RAFANTINI at salisbury.edu>
Cc: jeepp <jeepp at comcast.net>; MICHAEL ST ANGELO <mstangelo at comcast.net>; mrca at mailman.qth.net
Subject: Re: [MRCA] 24 volt power supply

The RF-350K is a 12 volt radio. The power supply takes in either 12 or 24 volts DC or 120 or 240 volts AC and makes the 12 volts for the radio. At one point I ran the radio part from a 12 volt battery and didn’t even use the bottom part.

Yes, lots of EMI filtering in there especially for the DC-DC part and also there is a fan for the rear radio heat sink. If you’re not running RTTY the big heat sink barely gets warm.

Peter

On Jan 3, 2019, at 3:59 PM, Ray Fantini <RAFANTINI at salisbury.edu<mailto:RAFANTINI at salisbury.edu>> wrote:
Have seen that form factor power supply used in a lot of commercial stuff. Have a couple Harris DAX-5 AM broadcast transmitters that use one of those at 48 volts  and they tend to just sit there and work in broadcast service but they do need to be on some sort of heat sink and have ventilation.
They work by using pulse with modulation and in no load or low load conditions there may be an issue, also I know that I have replaced several of the 48 volt power supplies over time along with a 13.5 volt one and if you take them apart they are almost impossible to repair. These days when I run across a dead one don’t waste time and just pull it and replace without opening up the failed one. They are so cheap why waste time?
My RF-350K has the Harris pulse with modulated multi voltage supply under that for providing the 28 volts for the radio that’s half the size of the radio and has a ton of filtering. Don’t know if the filtering was because possible RFI from the regulators or some EMP filtering but its way heavy.

Ray F/KA3EKH

From: mrca-bounces at mailman.qth.net<mailto:mrca-bounces at mailman.qth.net> [mailto:mrca-bounces at mailman.qth.net] On Behalf Of jeepp
Sent: Thursday, January 03, 2019 3:22 PM
To: MICHAEL ST ANGELO <mstangelo at comcast.net<mailto:mstangelo at comcast.net>>; mrca at mailman.qth.net<mailto:mrca at mailman.qth.net>
Subject: Re: [MRCA] 24 volt power supply

Mike,
I bought some 7A and 16A units from EBAY. They did put out some rfi.  However, using a Corcom filter on the a.c. input and some .001, .01, and a 1000uf on the output, plus installing it in a small cabinet and bonding everything, no more real issues.  That is, on 80 and 40 meters.  Given the cost... works for me.
Jeep K3HVG

Sent from my Verizon 4G LTE smartphone

-------- Original message --------
From: MICHAEL ST ANGELO <mstangelo at comcast.net<mailto:mstangelo at comcast.net>>
Date: 1/3/19 15:14 (GMT-05:00)
To: mrca at mailman.qth.net<mailto:mrca at mailman.qth.net>
Subject: [MRCA] 24 volt power supply

I finally got my Harris RF-5000 transceiver working over the Christmas holiday. It only puts out 100milliwatts so the next step is to interface it to the Harris 125 watt amplifier.

The amp requires 26 volts at 12 amps so I'm looking for a 24 volt supply. Does anyone have any experience with the 24 volts switchers used with CCTV and LED lighting applications. Here is an example:

<https://www.amazon.com/EAGWELL-Universal-Regulated-Switching-Computer/dp/B01IOK5FM0/ref=sr_1_6?ie=UTF8&qid=1546539277&sr=8-6&keywords=24volt+power+supply>

I'm concerned about the RFI it generates and the transient response with a varying load such as a SSB or CW transmission.

Any recommendations or suggestions are welcome.

Mike N2MS

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