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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | SGC SG-500 Smart Power Cube Help

Reviews Summary for SGC SG-500 Smart Power Cube
SGC SG-500 Smart Power Cube Reviews: 39 Average rating: 4.3/5 MSRP: $1395.00
Description: Amplifier: One KW - Model SG-500 SmartPowerCube
Product is in production.
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K3GK Rating: 4/5 Nov 20, 2009 07:10 Send this review to a friend
SGC TWEAK  Time owned: 0 to 3 months
As an addendum to my last comment, note I was working into a dummy 50 ohm load. Working into a real load may show different results. Tweaking your 'tuner' if you use one or working into a screwdriver, or more inductive load may show more 'apparent' output.
K3GK Rating: 4/5 Nov 19, 2009 06:09 Send this review to a friend
SGC 2009  Time owned: 0 to 3 months
This is my second Powercube, which allows me to compare apples to apples. I purchased the second unit recently for the home shack because I like my mobile installation, and the thrill of working DX and getting "you don't sound like a mobile station" is seriously addictive. The mobile installation is running at 14 volts and easily cranks out near 500 watts on all bands. 20 is my most often used band and the Powercube from 2007 gets full output into my Tarheel 100. The VSWR fault is disabled because the unit is too sensitive to RF at close proximity, but in high SWR the current fault disables the amp. My new Powercube looks similar but there is as stated by a previous reviewer a 'slump' on 20 down to about 300 watts. I asked SGC about this and I received a 'neat' corporate response about this being within specs and I should try more voltage or a different supply. The new amp is doing well on the low bands at over 500 watts and 17, 15, and 10 are also near full output. I decided to keep the second Powercube because I wanted an amplifier for the low bands and 300 watts is more than enough on 20 as I realize this
'slump' will not be heard at the other end. I don't know exactly why the two units differ, but I suspect perhaps new components or transistors, as I re-soldered the band five filter board and wiggled everything as suggested to no avail. If this small 'quirk' would irritate you, you might want to consider a 2007 model on the used market. Otherwise, the new Powercube is performing as my older one, like a rock. Bottom line, we are giving it a 4, and hoping SGC will think about hams as centered on 20 meters not 11 meters..
K0WJ Rating: 5/5 Oct 8, 2009 21:43 Send this review to a friend
WHAT AN AMP!!!  Time owned: 0 to 3 months
Well after owning an Ameritron ALS-500 for over ten years, I bought a new Chevy Silverado 2500HD Diesel four door pickup truck. The first issue I had was trying to deal with the voltage that sometimes would creep over 16 vdc. The local dealer said this was normal and could do nothing to remedy the situation. Come to find out, the ALS-500 couldn't tolerate this and subsequently burned up. RATS!!! I read the specs of the SG-500 Smart Power Cube and it stated a max input voltage of 18 vdc. So I ordered one from my favorite dealer, R&L Electronics in Hamilton, Ohio. They had it in stock and shipped it the same day and two days later, I was installing it. First I must say that it was truly ready to install as I had read almost all of Alan Applegate's (KBG) website and had followed all rules for proper installation of mobile gear. If you haven't been to Alan's site (, you need to.

After I installed the amp, I ran it through all preliminary tests per the SGC install manual. Everything tested normal, so I plugged the antenna in (Scorpion SA-680E). In the two months I've had the amp installed, I've had so much fun. Also, my Palstar mobile watt meter now registers over 500 watts which it never came close to with the Ameritron amp. In addition, the SG-500 is so much less fussy than the fault "intolerant" ALS-500. Now I just operate which is truly enjoyable. Almost every QSO I have, I am questioned: "Did you say you were mobile?"

KBG, Scorpion Antennas and now the SG-500 Smart Power Cube have given me all the advantages I need to put a first rate mobile signal on the air.
N3ZH Rating: 3/5 Aug 18, 2009 10:18 Send this review to a friend
Won't function 22 to 30 Mhz  Time owned: 0 to 3 months
Well, as you all likely know, every product gets hardware and software changes over the years. The SGC500 from years ago is not exactly the same as what rolls off the assembly line today. This applies to radios, tuners, and all equipment.

I ordered my SGC500 from R&L - they were out of stock - had to wait a month or so. It is fresh off the assembly line.

There are some new changes which are not reflected in the owner's manual - and not even on the printing on the amplifier. The final band pass is now supposed to be 22.2 Mhz to 30.0 Mhz. There is no mod required to use this bandpass filter - it is supposed to come from the factory already enabled.

For Auto band pass filtering, one needs to remove the cover and move the "Export" jumper. That's all.

BTW, I highly recommend people buy the external power switch - because it is more than a power switch - it is also your band pass filter selection knob. One position of the knob is for auto-band pass filtering. You must remove a jumper visible from the outside of the amplifier before attaching one of the power switch's connectors to the radio.

I had to call SGC tech support for locating the export jumper, and the external jumper. SGC would get fewer calls if they had a nice "getting started" brochure with pictures and directions.

OK, I primarily use the amplifier for MARS work from 4 to 5 Mhz - and it works great - I am very pleased. The amplifier can go a little further past 500 watts, but I don't want to over-drive it - plus the MARS limit is 500 watts at these frequencies.

However, I also tested the amplifier on each Ham band. And this is where I was very disappointed. From exactly 22.0 Mhz through 30Mhz the SWR goes way way up both at the tuner and the radio and the amplifier quits operating to protect itself.

I have an Icom 746pro radio to SGC500 amplifier to Palstar AT-AUTO tuner. With the amplifier off, I can transmit 100 watts with a perfect 1.0 to 1.1 SWR. I turn my radio's power down to the minimum and turn on the amplifier and swr goes through the roof.

Everything works perfectly at 21,999,999 Hz with a perfect SWR. But, moving to 22,000,000 hz and high SWR occurs.

It sounds like something defective in the last band pass filter. But, no - the final band pass filter does not start until 22.2 Mhz according to SGC tech support!

I suspect that it is either the final band pass filter, or else it may be spewing large amounts of stray RF which may confuse the circuits in the Palstar AT Auto tuner. However I don't hear sounds that the tuner making any changes to L and C, so I suspect all the trouble is within the amplifier.

Tech support started asking me to look for cold solder joints on certain components, but I'm not going to stick a soldering iron into an expensive amplifier that is under warranty. So, after owning the SGC500 amplifier just a few weeks, I sent it back to the factory for warranty work.

I called the factory today - and was told a coil for the last band pass filter was not soldered properly. It was resoldered in place, and the amplifier is on its way back to me.

When I receive the amplifier, if all works well, I will raise my review rating.
K5JAX Rating: 5/5 Jun 11, 2009 10:10 Send this review to a friend
Works very well  Time owned: 0 to 3 months
I bought this in May 2009. They seem to build them as you order. It took about three weeks.
All test were for PEP and not key down conditions. It is ONLY used as a BASE STATION unit. It is shipped as a full bandwidth amplifier now. I did need to go inside to change a jumper to allow it to auto switch the band filters. I am pleased with the way it switches them automatically. I previously owned a TenTec Hercules II amp which worked great but was limited to having a smart interface for band switching.
I have tested it with a number of watt meters, different Bird loads with different coax cables and transceivers. There seems to be a slump around 20 meters as to power out versus input. I talked with their engineer and he confirmed that it is not absolutely flat.
It makes 500 watts PEP out on all bands. On 160M and 80M it can produce a little over 600 PEP.
Their engineer inquired as to what supply I was using and indicated it was designed to operate at it's best with an unregulated 14 VDC supply as labeled. All test were done with a 4 gauge power cable. I used welding cable. I had to modify some power connectors to allow them to fit into the terminal block on the amp. Don't skimp on the wire gauge to make standard terminals work. I also used a 4 farad GSI brand capacitor. This also has 4 gauge cables about 1 foot in lenght and connected directly at the amp power in terminals. This allowed even the Astron supply to produce impressive PEP outputs. I believe the cap is critical to the operation. The Astron got extremely hot as you would expect and was not going to be the operating supply.
I thought about the Optima battery route but they are quite expensive and still need a stiff battery charger.
I was told by the factory that a switching supply would not work due to RF contamination.
I still tested an "Intelli-power" model PD9280.
This has worked out very well because it is rated at 80 amps out. I tested it with a DC load and it can produce 83 amps. I also bought the little control that plugs into the power supply and with it you can switch between operating modes since it is a SMART supply.
It has a 13.8 power up normal mode and a charge boost mode which is 14.2 VDC and an automatic float mode. All of these are controlled by a processor. With the remote I can force it into the 14.2 volt mode after applying 120 VAC. This works very well because now I match the design voltage for the amplifier. I have been using it on the air with the Intelpower and the 4 farad cap and I have had very good reports. You can place the amp out of sight but still where you can reach the on/off switch.
I have added a 6" diameter DC fan to the unit and it keeps it really cool. I took pictures of the fan installation. I will post the article on my website 73's
N4NOO Rating: 5/5 Feb 23, 2009 09:57 Send this review to a friend
Very, very nice!  Time owned: 0 to 3 months
I use this with an Icom 7000 and a Hi-Q 6/160 RT/MC-3-H antenna in my Suburban and it makes a world of difference. The most common reply is "That's the best sounding mobile I have ever heard". If you want that extra bump, this is a great amp. It has been perfect from the first time on the air. No problems at all. Try it, you'll like it!
ZS1DDK Rating: 5/5 Sep 19, 2008 06:52 Send this review to a friend
Excellent Workhorse  Time owned: months
I have 2 Cubes installed in my shack and have used both for the past year. It is an excellent workhorse and operates flawlessly. The protection circuitry makes it absolutely IDIOT- proof !
My advise: Cut a polycarbonate sheet to fit over the bottom of the amp, install 2x12v fans side-by-side onto the polycarbonate sheet(Cut holes in this sheet the size of the fans obviously). Your fans are switched on by the thermal sencing of the amp ! Now you can run as many band pile-ups as you like - no problem!
9V1VV Rating: 2/5 Jul 7, 2008 22:41 Send this review to a friend
Overpriced  Time owned: more than 12 months
The design is very good but if you study the schematic you will see that a lot of expense is involved with the uP controlled protection circuitry for the bipolar finals.

The Ameritron and Motorola 4 x FET 600 watt designs are much simpler and cost much less becaue FETS are less prone to damage and do not need such elaborate protection.

The Ameritron equivalent includes the power supply for about the same price as the SG-500, which requires a separate 100 Amp PSU.

Also, the fan kit for SGC-500 is a ridiculous price. You can make your own for a few bucks.
W8NYY Rating: 4/5 Jul 7, 2008 10:02 Send this review to a friend
Great Amp for Mobile Operation  Time owned: 0 to 3 months
I had a bit of a rough start with the SG-500. Placed the order back in March and found I was going to have to wait 90+ days for it to arrive. Being an impatient sort, I decided to spend the time making sure my mobile install was done right. My mobile installation is a Honda Ridgeline truck and decided to install this under the back seat. Got a tremendous amount of help from Alan Applegate, K0BG, and the fact that he also drives a Honda Ridgeline made his help just more invaluable.
Bonding, more bonding, 4 AWG wire runs, Maxi fuses, an Optima Red Top Battery, a 1 farad stiffening capacitor and a whole bunch of ferrite beads and more ground straps and I was ready for the SG-500. About a week after Dayton the SG-500 finally came in. As I said, my initial experience was rough. Immediately started experiencing relay issues. The amp wouldn't return to receive. As recommended I manually played with the relays a bit and that problem went away. Then I immediately started having CURR faults. I checked and rechecked everything and then finally called Tech Support at SGC. Their advice was to ship it back saying it had to be an internal issue causing the variance of current to the amplifier modules. I shipped it back UPS ground insured (gulp!) and called them the day after they signed for it. Their immediate response was it would be 4-5 weeks before they could look at it. I explained (with passion) that I had yet to have a working SG-500 and after waiting 3-4 months for the shipment it was unrealistic for me to have to wait another 4-5 weeks before they would even look at it. After some mutters of "we'll see what we can do" I hung up and in desparation called AES in Cleveland, where I purchased it. I spoke to Ben, the manager of the Cleveland location. Ben listened to my story and said he'd call me back after he made a phone call. Ben called back in 15 minutes and said he'd have a new one shipped the same day, and I'd have it the next and explained he'd deal with SGC and the other unit.
AES may not be the cheapest guys on the block, but their service and support is A++. Thanks Ben.
As promised I got the new unit the next day and after making the simple 10 meter mod (they no longer make you connect the loose wire - only a jumper change now)I put it in place in the Ridgeline. I ran it through it's set up and tests and outside of having to install one more ground cable (engine header to frame) which eliminated a fuel injector issue when transmitting on 20 meters, the SG-500 has been working flawlessly ever since.
I was more than a bit concerned after my initial experience with the first unit but now I can say, I am very pleased with the SG-500 and consider it the crowning glory to my mobile set up. Only problem is I'll never be able to sell the Ridgeline but why would I want to do that anyway? It's just the way I want it.
I rated this a 4 because of the issues with the first unit otherwise it would have been a solid 5. Pictures of my install can be seen on Alan's site at
W9BR Rating: 5/5 May 16, 2008 07:50 Send this review to a friend
Terrific Amp - Gets you over 500 watt HF hurdle  Time owned: more than 12 months
I own two of these amps. They are both incredible ampliers. Actual SSB output as read on highly accurate peak reading meter is 600 to 650 wattas PEP. These amps are bullet proof. They have so much protection for SWR, current, voltage, etc. that you cannot ruin them. Those people that complain about this amp do not hook it up right, or do not have enough voltage at the B+ terminals. Use a 1 or 2 farad cap at the terminals. Easily availabe on E-Bay or Circuit City now as the kids use them mobile for thier boom boom amps. Remote controlling this amp is a breeze as they have a remote on/off/reset terminal available that also has LED indicator voltage. Cooling fan required for CW/AM. Easy to hook up your own fan!! 30-35 wattas drive is all you need for full output

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