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Author Topic: Mega-Watt power supplies  (Read 17301 times)
K2OWK
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Posts: 1055




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« on: November 14, 2010, 03:51:20 PM »

I think I asked this question before. I just purchased a Mega-Watt brand power supply from Electronics_5000 on EBay. I have not received it yet. It is rated at 36 amps 12 volts to 13.8 volts variable. The 36 amps is 90% duty cycle and at 30 amps it is 100% duty cycle. It is sold as a Ham Radio transceiver power supply. The specifications are very impressive. The seller has a 100% good feedback for a couple of thousand sales of this supply. It sells for $65.00 plus $5.00 shipping. I just bought a new Yaesu Ft-450AT which I hope to use it on. I have not received the transceiver yet, it to is on the way. The Yaesu power supply is $150.00 plus shipping, and has a rated output of 20 amps at 13.8 volts. Just enough to drive this radio on transmitt. Both the power supplies are switching types. Like I said before The Mega-Watt has excellent specifications as far as ripple, regulation and a built if fan that comes on when the supply reached a certain temperature. My question is does anyone out there have any experience with this supply used as a transceiver power supply? I do not see a rating on it on the Eham reviews yet. I will be the first one to rate it if it works for this purpose. The reason I ask if any one has used it for this purpose is I do not want to hook up my brand new $700.00 radio and have it smoke. Of course I will check the supply out carfully for voltage, AC ripple, spurious frequency' and Voltage Current regulation before hooking it up, but it will be of benefit to me and maybe others who may consider using this power supply.

Thanks,
73s
K2OWK
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KB4QAA
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Posts: 2335




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« Reply #1 on: November 14, 2010, 08:29:01 PM »

How many opportunities does a fellow get to hook up a brand new radio to a brand new power supply?  Wink
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AD6KA
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Posts: 2237




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« Reply #2 on: November 14, 2010, 08:33:57 PM »

Quote
The reason I ask if any one has used it for this purpose is I do not want to hook up my brand new $700.00 radio and have it smoke.

I would've spent the $35 more for a brand new Samlex 1223 ($99.95 at
HRO and others) or an Astron, rather than wring my hands and worry over an unknown
PS for a brand new radio, but that's just me.






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K2OWK
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Posts: 1055




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« Reply #3 on: November 14, 2010, 09:24:19 PM »

Hello AD6KA, I checked the reviews on the Samlex 1223 and while most are good there are a few that indicate a problem with RF noise on the HF frequency's that I will use most often. Some of the reviews also indicated poor manufacturing service when the unit fails. The Astron looks more expensive and appears to have about the same specs as the Mega-Watt. By the way the Mega-Watt is a brand new supply with a full warrentee and the seller is in the US (I am sure the supply is made in China but isn't everything, except MFJ). I was hoping someone out there had used the Mega-Watt unit and could tell me something about it, but I guess I will find out for myself in a few days. I will be sure to do some through testing before hooking it up to my new transceiver. I have a good amount of test equipment, and will give it a good burn in before using it. I will post a Review about it after I have used it for a while for its intended purpose.

Regards,
K2OWK
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KASSY
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Posts: 165




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« Reply #4 on: November 15, 2010, 01:32:49 PM »

A dumb question:  Why did you spend this money before asking questions?  Is this a new form of buyer's remorse?


First off, stuff sold on ebay could be anything.  I've bought stuff with "specs", that when I got them, fell far short of meeting those "specs".  So, don't believe the claims about ripple, bla bla.  Also, ripple tells you nothing of radiated EMI...they could be horrible.

All switching supplies in my experience make noise.  Some worse than others.  No matter whose switcher you buy, if you want to operate 160 or 80, you will be chasing down noise.  IMO, if this is important to you, and you're not handy with RFI cures, buy the Alinco DM-330V.  Not cheap, but it's got a knob that allows you to change the switching frequency.  So, if there's a nasty spur on the frequency you want to use, just twist the knob, and the spur moves.

GL

-k
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K2OWK
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Posts: 1055




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« Reply #5 on: November 15, 2010, 03:44:32 PM »

Kassy, The research I did was to carfully check the feedback of Electronics_5000 who sells just power supplies. The feedback on the transceiver power supplies are from hams. There is no bad feedback on this use. Actually he has no bad feedback on any use for the power supplies he sells. His total feedback is 100% good (much better then some ham outlet websites). If I had the money I would buy a transformer type non switching power supply, but this type of supply is very expensive new (more then the transceiver at the power rating needed) and even used on EBay it is much more expensive then the new Mega-Watt unit. If worse comes to worse which is unlikely, I will use the power supply to charge a 12 volt led acid battery of the type used on lawn tractors as a filter. The pure DC from the battery should present no RF interference to the receiver. I have used this method many times in the past with excellent results. So my purchase of this supply (which has been around for a while) will work out for me even if I use it for a test bench supply. For the price I do not believe I can go wrong plus the seller has a 100% return policy if I am not satisfied.

73s
K2OWK
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KB9WIS
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Posts: 180




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« Reply #6 on: November 15, 2010, 07:07:10 PM »

K2OWK, if you already done your research (read feedback from other hams on Ebay) and don't want to hear opinions on not buying it, then why are you asking?  Or are you promotiing it (I'm confused)?   

By the way, a Pyramid is also affordable and works very well for ham use, however 5 years down the road they tend to break down fairly often.  Feedback on Ebay only tells you their thoughts after initially buying it, nothing after 5 years (or even 5 months for that matter).  There is a lot of cheap brands out there, however the brands like Astron have a track record of lasting a long time..  You could have problems after only 6 months..
« Last Edit: November 15, 2010, 07:09:44 PM by Scott R. Archer » Logged
K2OWK
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Posts: 1055




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« Reply #7 on: November 15, 2010, 08:35:04 PM »

KB9WIS, I posted this forum to see if anyone had used this supply, as there is no review on it in Eham. No other motive. I have not heard any information from anyone who has actually used this supply. That's all that I was asking. I guess no one using this forum has used the supply. The information I have received so far is very much appreciated and I do take all information seriously. I remember the information and keep it for future reference.

Thanks to all who have replied.
73s
K2OWK
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NA0AA
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Posts: 1043




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« Reply #8 on: November 15, 2010, 08:46:20 PM »

Never heard of them, but that is a pretty low price for a 30 amp switcher.

I'll be interested in hearing where you buy them besides on line.
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KASSY
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Posts: 165




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« Reply #9 on: November 16, 2010, 11:27:24 AM »

Kassy, The research I did was to carfully check the feedback of Electronics_5000 who sells just power supplies. The feedback on the transceiver power supplies are from hams. There is no bad feedback on this use. Actually he has no bad feedback on any use for the power supplies he sells. His total feedback is 100% good (much better then some ham outlet websites). If I had the money I would buy a transformer type non switching power supply, but this type of supply is very expensive new (more then the transceiver at the power rating needed) and even used on EBay it is much more expensive then the new Mega-Watt unit. If worse comes to worse which is unlikely, I will use the power supply to charge a 12 volt led acid battery of the type used on lawn tractors as a filter. The pure DC from the battery should present no RF interference to the receiver. I have used this method many times in the past with excellent results. So my purchase of this supply (which has been around for a while) will work out for me even if I use it for a test bench supply. For the price I do not believe I can go wrong plus the seller has a 100% return policy if I am not satisfied.

73s
K2OWK

Now I'm even more puzzled.  As others have pointed out, ebay feedback means very little.  It's supposed to be about whether the seller handled the transaction succesfully.  If the item received was junk and the seller accepted it and refunded the money, it is still a "positive transaction". If you read down the pages of the seller's feedback, you will find exactly those comments...power supply was junk, very noisy, and seller accepted it back gracefully."

And, you said "I would buy a transformer type non switching power supply, but this type of supply is very expensive new (more then the transceiver at the power rating needed)"...you also said your transceiver was $700.  I challenge you to show me a $700 transformer type power supply.

FWIW, your FT-450 will run just fine on an Astron RS-20A, readily available from many stores for $89.95.  A nice, quiet linear supply.  If you need high duty cycle, then upgrade to the RS-35A for $159.95.  Neither of those is "more than the transceiver"...not even close.

If you feel misgivings about the supply, then send it back.  If you don't feel misgivings then just use it.

-k
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KD4LLA
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Posts: 454




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« Reply #10 on: November 16, 2010, 07:27:58 PM »

Someday you will regret buying the MegaWatt (I tried to find info via Google, there is none) and will buy a Astron 35 Amp.  @90% duty cycle you will just barely keep the radio on.  I used to have a Astron 20/16 with my Yaesu Ft-890.  After fifteen minutes the radio would start shutting off during transmit.

Sorry to break your bubble...

Mike
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K2OWK
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Posts: 1055




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« Reply #11 on: November 16, 2010, 10:24:49 PM »

KD4LLA, The duty cycle is for 35 amps. The 100% duty cycle is for 30 amps continuous. The radio draws a maximum of 21 amps on transmitt at full power. This power supply should be loafing at that current. I do not understand the hostile response to a simple question about a power supply I found interesting and purchased for a low price. Low price does not always mean poor quality. I have a Wouxun HT that was a super cheep. I have had it for a while, and is an excellent unit. If we do not try an item that comes out just because it is a low price and does not have a track record, many small companies will not make it and some good equipment will be lost. To me Ham radio is all about experimenting with different types of equipment and having a good time in the process. I have been doing this for more then 50 years. Some of the equipment I have bought is junk and is no longer available. Some is now very high quality and is used by everyone. Remember Amaco, how about Telerex, look at the adds in QST and see how many companies started out with a product was unknown at the time, and is now highly sought after. Like I said in my original post, I was looking for someone who had used this supply. Without an answer at this time. When I get the supply I will test it and use it for my transceiver. Wheather it turns out to be a good unit or a piece of junk I will let this forum know and post a review. That's how we find out what is good and what is bad, but I can not judge a piece of equipment just because it is low priced or high priced for that matter. High priced equipment can be just as bad as low priced equipment. As for a power supply that lasts for 5 years. I would be very happy if this supply lasts 5 years and would feel I got my moneys worth.

                There are many transformer power supplies that cost a bundle HP instrument grade voltage and current regulated supplies, but that is not the point. I could buy a Yaesu transformer power supply that is made for this radio for about $200.00, but I choose to try this cheapo just to see how it works.

               Why are people getting so upset at this post and question?

73s
K2OWK

   
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N4CR
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Posts: 1662




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« Reply #12 on: November 17, 2010, 12:12:17 AM »

Because you asked for the opinion after you already pulled the trigger. Ready Fire Aim is what we see.
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73 de N4CR, Phil

We are Coulomb of Borg. Resistance is futile. Voltage, on the other hand, has potential.
W3LK
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Posts: 5644




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« Reply #13 on: November 17, 2010, 07:40:21 AM »

People who buy unknown brand equipment off eBay often receive rude surprises when the equipment fails to perform as advertised (or fails completely) and there is no dealer/manufacturer to resolve the problem.

I hope you are not one of them, but I wouldn't be putting any money on that hope.

The original difference in price between unknown junk and quality products is far less than the cost of replacing the the junk.
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A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
KD4LLA
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Posts: 454




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« Reply #14 on: November 17, 2010, 10:00:57 AM »

Oops, I DID fail to see that you stated the power supply is 35 amp 90%/ 30 amp 100% duty cycle, my apologies.  I am still haunted by my own use of a 20/ 16 amp Astron PS (since upgraded to a RS-35M).

Mike
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