Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Which Power Supply For Motorola Spectra?  (Read 5636 times)
KD8HMO
Member

Posts: 228




Ignore
« on: September 15, 2012, 06:56:08 PM »

Can anyone reccomend a good quality, but not too expensive 12v power supply that will run my 110w Motorola Spectra? Im told this radio will draw around 22 amps on transmit, and at least for now, it will be the main user of the supply. I dont know if I need a switching or non-switching supply. Any help would be appreciated.

Logged
KC9NVP
Member

Posts: 71




Ignore
« Reply #1 on: September 15, 2012, 08:11:53 PM »

any switcher or non-switcher (Liner) that is capable of supplying the 22 amps without going into current limit should work.  The switcher will be smaller and maybe more expensive then the liner which will be bigger (larger transformer) and heaver then the switcher.  Some switchers can produce noise that will interfer with the radio, so check the specifications to see if they included output filtering.  Switcher by design will bring the input AC in and convert it to DC by chopping the AC at some freq and then rectify it to DC.  Liner use a transformer to step the AC line voltage down to 15 - 20 volts and then rectify it into DC.  This voltage is then fed thru pass transistors that bias on to regulate the output voltage at 13.5 volts.  The quantity and type of transistors along with the transformer will determine the output current capability of the power supply.

Another possibility would be to use a smaller power supply in parallel with a battery such as a deep cycle type to run the radio.  The high current draw would come from the battery during transmit, and the power supply would recharge the battery during the times you are listening.  This would require a blocking diode between the battery and the power supply such that when the supply is turned off, the battery will not discharge back into the supply.
Logged
KA4POL
Member

Posts: 1996




Ignore
« Reply #2 on: September 15, 2012, 10:07:33 PM »

Power supplies are often advertised with the highest current. However, this is usually not continuous current. So watch for that. As you mentioned 'at least for now', getting some overhead would be a good idea.
There are lots of different brands to chose from. To mention just one: Astron.
Logged
K4JJL
Member

Posts: 492




Ignore
« Reply #3 on: September 18, 2012, 09:07:55 PM »

Astron 35 will run it ok.  Astron 20 will run it, but not be very happy if you decide to be net control or sit on your mic.

I ran a 100w GE Mastr II mobile on a "loaf of bread" Motorola power supply (rated at 10-15 or so amps).  It worked for about a week, then pooped the bed.

You can use a GE Mastr II station power supply if you don't mind the ferroresonant transformer buzz.  I offer those to friends all the time, but they usually return them within the month.  If you loan out equipment with annoying bugs (or "features"), it always finds its way back home.

You can go into the alignment menu and turn down the power if you don't have a monster supply.  Make sure you adjust the current limiter while doing so.  The 3db difference from 100 to 50 watts isn't that noticeable.  Ask someone with a service monitor to give you a demonstration.  I show this to repeater owners who can't work on their own equipment all the time.  Blows their mind.
Logged
WB6DGN
Member

Posts: 619




Ignore
« Reply #4 on: September 20, 2012, 01:27:15 AM »

Quote
Astron 20 will run it, but not be very happy if you decide to be net control or sit on your mic.

Radio isn't going to like that very much either.  A Spectra, is not rated for continuous duty (and neither are most other mobiles), especially at full power.  Best match is probably the RS-35.  If you do reset the output power, don't go lower than about 50% of rated power.  Some transmitters get a bit unstable if power is reduced too low.
Tom
Logged
K4JJL
Member

Posts: 492




Ignore
« Reply #5 on: October 06, 2012, 08:59:28 PM »

Radio isn't going to like that very much either.  A Spectra, is not rated for continuous duty (and neither are most other mobiles), especially at full power. 

I gave a friend a high band Syntor 9K to use because he kept burning out his Icoms running 2 hour nets.  Set it for 100w.  Haven't heard him complain yet except that he burned out his Astron 20.  I offered him a GE power supply from a base station.  He declined immediately after he powered it on.  I guess the ferroresonant transformer was a bit too much for him.
Logged
WB6DGN
Member

Posts: 619




Ignore
« Reply #6 on: October 07, 2012, 12:32:39 AM »

Quote
He declined immediately after he powered it on.  I guess the ferroresonant transformer was a bit too much for him.

Wise choice!  Ferroresonant supplies get what regulation they have through the resonant winding which keeps a partial load on the transformer.  Therefore the idling current on those supplies is horrendous.  One of my favorite radios (MSF5000) uses resonant supplies and, if you have to pay the power bill, they'll eat you alive.  Technically, adequate.  Economically, a disaster.
Tom
Logged
K4JJL
Member

Posts: 492




Ignore
« Reply #7 on: October 10, 2012, 04:28:56 AM »

He was grousing about the noise, not the power consumption.   Cheesy  He didn't even take it home.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!