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Reviews For: Diamond SG-7500NMO (Super Gainer series)

Category: Antennas: VHF/UHF+ Omnidirectional: verticals, mobile, etc

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Review Summary For : Diamond SG-7500NMO (Super Gainer series)
Reviews: 22MSRP: 79.95
2m/70cm NMO-mount mobile antenna
Product is in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
K9FE Rating: 2012-04-16
Good and solid Time Owned: more than 12 months.
I ran the 7500 for 6 years and then I started having SWR issues (2.5:1). Well after 6 years of Chicago weather it did not surprise me. While down in Orlando I stopped at AES and replaced it. Put it on the car and everything was back to normal. I returned back to Illinois and was looking at the original 7500 and found the lower matching coil unscrewed from the upper antenna section. (below the hinge assembly) I unscrewed it and found an o-ring seal and corrosion on the tip of the contact point. Got out my trusted De-Oxit and cleaned the tip and the antenna contact point. Assembled it with some Corrosion-X hoping that it would prevent it from happening again. Antenna checks out beautifully now with a 1.15 SWR at 146.000. Now I have a spare.

My problem was I did not know about the contact that could be serviced. Diamond makes fine products and as I found out they can be serviced. Diamond has been very responsive in getting me replacement parts. The first 7500 was given to me after it when through a car wash and the owner forgot to remove it. Resembled a corkscrew after it came out. I e-mailed for a replacement rod and a center replacement coil for a different 7900. I had them withing a week and for a very fair price.

If you have problems with the fold-over folding at highway speeds AND you really do not need it to fold over I found that a 2 inch section of heat shrink tubing (1/2" size) will keep that from happening.
W9DPY Rating: 2011-09-16
Solid and capable Time Owned: more than 12 months.
Was looking at a Comet CA-2x4SR to upgrade my ever expanding antenna collection. I have been running the Larsen 270 for convenience; as longer antennas drag on the parking garage at my work. In the end I threw back on my SG-7500NMO. I'm on my second one - the first one broke at the "tilt over". At first I was mad, but then realized I had the antenna 7 years and drove it through Chicago winters and Austin summers.

This antenna is great. I use the actual NMO version, mounted on a Diamond trunk lip mount. I have driven it with everything from a Kenwood TH-F6A to a full 50 watt Yaesu mobile. Always good signal strength reports. Did some "low tech" antenna testing between the 270 and the SG; with another ham 20 miles away. Reports were solidy in favor of the Diamond.

Lately, I have read reports of the quality of Diamond going down. I hope not - I have two of their mobile antennas, an X50 in the attic and three of their H/T antennas. All are great - so a 5 from me for this product.
W3RXO Rating: 2010-07-05
Not very happy with Diamond, Right now. Time Owned: 6 to 12 months.
I rate this one at a dismal, 2, as I have had a few problems, and am beginning to wonder if Diamond might not be having some QC problems, right now.
First, let me explain, I am a darned loyal Diamond user. I run an SG 7900 on my mobile, and on the mobile I keep in my wife's car. I have an NR770HB on my motorcycle, and ran an SG7500 on my work truck, sort of. It has been OFF the truck, more than it has been on the truck. My backup antenna for the truck is an NR77oHBNMO. I also run Diamond antennas for my base (510X) and HT (SRH320A), as well as a few other applications. Yes, I have always been loyal to Diamond, as I have always been happy with their products, until now.
I bought my first 7500, after about a year and a half of great service from my 7900's, and considering that several friends, whose recommendations I value greatly, recommended the 7500, HIGHLY, I decided to get the 7500 for the work truck, as Diamond does not recommend the use of a 7900, on a large commercial vehicle, due to it's length, and the vibrations causing trouble.
The first 7500 I bought, from HRO Anaheim, was purchased new, but when I got it to work, my next day at work, I went to take it out of the package, to install it on my existing NMO mount, and it fell apart, in two pieces, in the middle of the lower coil. I chalked this up to being an anomaly, and a week later, took it back to HRO, for a replacement.
HRO was gracious enough to replace it, and even looked it over thoroughly, saying, "Yep, it was NOT stressed, it was a defect". They gave me another new SG7500NMO, and off I went.
A month and a half later, I am driving down the road, and hear a "clinking" noise, on the catwalk, behind the cab. When I stopped, I looked to see what it might have been, and sure enough, the top section was missing, from the middle of the top coil, up.
Now, this antenna, is mounted high, above the rear window of a 2008 Freightliner daycab, and behind a fiberglass fairing, centered on the cab. For it to have been hit by anything, the fairing would have sustained serious damage, and the trailer likely would have, also. No damage to either.
A month of emails later, between Diamond Japan, me, and RF Parts, their US Distributor, I finally got an RA number, to return it for them to look at it, and "see if it is covered under warranty". I got it back 2 days after shipping it (Great turn around time) with a note that said:
"Antenna was hit by something. Lower element is bent. Diamond Japan is warranty this antenna".
While there WAS a SLIGHT bend in the section between the lower coil and the middle coil, I can assure everyone, it was not from hitting ANYTHING.Could it have been mishandled, or some other treatment cause the slight bend? Sure. But it did not hit anything. Even if it had, do not these antennas have enough ruggedness, to withstand a normal strike, from a foreign object?
While I am grateful that Diamond Japan covered this item, and got it fixed, I am not very confident that anyone will receive proper service, when they turn to RF Parts, for their warranty work, and seriously doubt that Diamond's QC is what it once was. While I have always been very happy with Diamond antennas, in the past, I would look for others, before I settled on a Diamond, nowadays.
Sorry, I must rate it a dismal 2.
KF4ULD Rating: 2010-01-07
What a difference from a 1/4 wave 19 incher Time Owned: 0 to 3 months.
This thing is outstanding, especially compared to my MFJ 19" mag mount it replaced. I now can turn down my power and hit and hear the repeaters that used to be very weak. I like the fold down feature and find myself using it weekly driving into parking garages in Seattle. Not having to use high power on APRS means I don't hear interference any longer on my Sirius unit when my APRS beacons on 25 watts instead of the former 50 watts with the 1/4 wave. I highly recommend this for mobile or an urban base antenna. The only improvement I would make is to have a set screw on the base you could secure it with after screwing it onto the mount.
KF4ULD / Matt, Seattle, WA
KJ4AQT Rating: 2008-02-03
Awesome Antenna Time Owned: 0 to 3 months.
I have had this for a short time but it has proven to be an excellent performer, it is mounted on my mirror of my Volvo 770 18 Wheeler and has been through 2 ice storms, it has folded over both times but went right back into position

i would definately reccomend it
KC7KMP Rating: 2008-01-30
Excellent Antenna period Time Owned: more than 12 months.

Used for 4-5 years now and it still works great (with 5" magmount). Taken a few low branch/parking garage hits with no perceptable performance hit. Looks like its been used for fencing but its still the best mobile antenna I own and would highly recommend it.
KA7OEI Rating: 2007-06-05
Solid and well built Time Owned: more than 12 months.
I've had this antenna mounted on my Jeep for over a year now, having taken it on some bad roads with low-hanging branches and have not had any problems. Having it on the left (driver's) side of the vehicle has helped, as that puts it farther away from most antenna-damaging trees and bushes.

I did note that the VSWR on 70cm was not flat - about 1.7:1 in the repeater subband, but that is of little consequence, really, as this doesn't put much stress on the finals, and this doesn't amount to much additional loss in the fairly short coax run inside the vehicle.

I have seen problems where others have mounted similarly long-ish antennas on rather flimsy mounts: This will stress the antenna more than a rigid, non-flexing mount, actually - especially if mechanical resonances are set up while driving. I used a modified, very heavy stainless-steel CB-type mount that I redrilled with a 3/4" hole for the NMO and then die-ground out enough of the mount to be able to install the NMO onto the antenna mount's thick metal (which was too thick for a standard NMO.) All of this has paid off with a super-rigid, stable, and rugged mount.

As for its actual performance: It seems to get out and "hear" at least as well as other antennas - what more could you ask for?
KZ1A Rating: 2006-10-04
Outstanding Mobile Antenna Time Owned: 0 to 3 months.
I to have the UHF mount style of the SG-7500.
It is, by far, the finest VHF/UHF mobile antenna I have owned to date.
Solid construction and solid performance.
KB3MMX Rating: 2006-07-10
Excellent performer!!! Time Owned: 0 to 3 months.
I have the UHF style base antenna and the performance from this antenna is astounding!
I replaced a Hustler CG-144 BIG 2 meter only antenna which really performed well for 2 M.
I was suprised that the Diamond antenna about 2/3 the size of the Hustler actually outperformed for RX and TX in several spots of my daily commute. I was also suprised to see how far away I could work our "low profile" UHF repeater!!
Excellent product, would definetely recommend it to a friend!!
K8APS Rating: 2006-03-11
Best mobile yet Time Owned: more than 12 months.
In use for almost five years now on permanent installs and mag-mount installs. Works awesome all around with my IC-2800H. I get much better TX/RX than many other hams with this setup. And parts are available from the manufacturer. I know this because I rolled a vehicle and had to replace the fold-over section and recently after all these years the upper most phase coil broke (this could have occured at a car repair place when it was on the lift). Either way, I've VERY satisfied and will recommend this antenna to anyone. Only drawback is it is very rigid so if you off-road it will hit low branches... not a problem with a mag mount that can tip over but not good on permanent installs. I had a through the roof mount on my Ford Ranger and it was a pain to fold it over every time I drove in the woods. However, now have a Chevy K1500 with mag mount and it I hit branches I just let it get knocked over and I set it back up when I'm done. It has never fallen over on the highway, even at high speeds. Again, a great antenna.