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Reviews Categories | Amplifiers: RF Power - 6M/VHF/UHF+ | Mirage KP-1/2M In-Shack GaAsFet Pre-Amplifier Help


Reviews Summary for Mirage KP-1/2M In-Shack GaAsFet Pre-Amplifier
Mirage KP-1/2M In-Shack GaAsFet Pre-Amplifier Reviews: 8 Average rating: 4.0/5 MSRP: $139
Description: 2 Meter/144-148 MHz In-Shack GaAsFET Pre-Amplifier
-Automatic RF switching
-GaAsFET boosts weak receive signals
-In-Line design for easy operation
-High or Low switchable gain setting
Gain: from 15 db to greater than 25dB
Noise: less than 0.6dB
Power Handling: 100 Watts
Size: 4 1/4 W x2 5/16 H x 1 3/16 D inches
Product is in production.
More info: http://www.mirageamp.com/products.php?prodid=KP-1-2M
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VE6ND Rating: 4/5 Jan 14, 2016 13:59 Send this review to a friend
Good basic preamp  Time owned: 3 to 6 months
I bought this used about 4 months ago and it works very well. Gain measured is 21dB with very little noise, around .6dB.
It is an older model but made still by MFJ.
 
N7BOO Rating: 5/5 Apr 27, 2014 14:30 Send this review to a friend
MFJ Preamps  Time owned: more than 12 months
First, Mirage / MFJ preamps whether mast mounted or in shack, are made for specific frequencies, there’s no single preamp that covers all bands, another words, they are made for specific bands and none of their preamps cover the entire HF band, one size doesn’t fit all frequency applications. You can go to the MFJ website and under Mirage, you will see the various preamps they have available and what frequencies they cover.

One of the problems, going all the ay back before MFJ was even involved, was the GaAsFET they were using in their preamps had a history of failure, more specifically, the GaAsFET was a NE25337 for which there is no longer a cross reference for a replacement. Another issue was the switching used to disabled the preamp when RF from a transmitter was applied, the switching was too slow and eventually over time the NE25337 GaAsFET would fail, go dead. The fix is a simple one, read on:

You can use a MGF1302 GaAsFET as a replacement. The MGF1302 is a better GaAsFET preamp with a lower noise figure and better gain, they can be had from RF Parts, I purchased two and with shipping they cost me around $30.00.

I had to replace the original NE25337 GaAsFET in both my B-5016-G 2 meter amplifier and in a Mirage KP-1 2M shack preamp, they have been playing ever since without any issues.

I have owned these amps and preamps for 20 years and they're still playing.







 
WA4GCH Rating: 1/5 Mar 23, 2011 08:40 Send this review to a friend
Near junk  Time owned: more than 12 months
It took 3 of them before I got one that worked and it is a sad peace of junk.
 
K3ROJ Rating: 5/5 Feb 25, 2010 18:40 Send this review to a friend
Ideal Preamp  Time owned: more than 12 months
Have never used an amplifier on 2 meters so this unit works well when running a typical 100 watt transceiver. Instead of using the preamp in the shack, I have it installed inside my garden shed where the 2 meter and 70 Cm antennas are mounted on the roof using a roof tower, rotor and masts. Having power in the shed made it easy to hook up. Apparently caused by nearby storms, the Gasfet has failed 2 times over the years but found some on E-Bay cheaply. After the second storm, I installed special clamping diodes on it's input gate and is working well. This preamp was necessary since my direct burial RG11 runs more than 100 feet to the shack.
 
K3ICH Rating: 5/5 Dec 20, 2008 06:39 Send this review to a friend
Works fine for me  Time owned: more than 12 months
I have no complaints with the pre-amp. It does what I'd expect, and that is to overcome feedline loss in receive. Most off the shelf radios these days have decent front ends, so an amp in the shack usually doesn't do much more than raise the S-Meter reading. The proper place is close to the antenna. Now, if you've got only about 30 feet of 7/8" hardline feeding your 2M antenna, you probable won't have much to gain

However, in 40 years experience with VHF/UHF operation and many different receiver pre-amp designs, one characteristic of GaAsFET's comes to mind. I have seen many units exhibit what appears to be plenty gain (noise level at the Rx goes up when switched in) but the actual signal readibility goes DOWN. Simply put the FET is blown, usually from transmitting up into it's output! Proper timing of the pre-amp T/R switching should prevent this, but as careful as we try to be, most switching schemes can be subverted.
If you're experiencing this situation, change the FET, you've managed to smoke it. Most of the common GaAs FET's in use today are under a couple bucks with the better ones under $20. Mouser, DigiKey Jameco etc. all stock them.
 
WD4ELG Rating: 2/5 Dec 20, 2008 00:06 Send this review to a friend
Return to sender  Time owned: 0 to 3 months
Maybe it was me and my old age, but the device increased the noise without really increasing the signal. And I could hear the signal with the preamp off, so I thought "What good is this thing?" Not working for what I was expecting. Disappointed.
 
K5YY Rating: 5/5 Apr 7, 2005 20:31 Send this review to a friend
just great for the HP exciters  Time owned: more than 12 months
I do a lot of weak signal work on 144mc and have for 30 years. This is a nice "in shack" addition and a MUST for most 2m transceivers, even those with built in preamps. Works flawlessly and handles the 100 watts. ARR is great too but only good for 25-30 watts. Most of us use 60-70 watts to drive a linear, so the higher power handling is necessary.Mine is powered by the 12v going down the inline coax, works fine, simple. Well worth the price.. San K5YY (496 grids on 2m with WAS)
 
AD5TH Rating: 5/5 Apr 7, 2005 19:33 Send this review to a friend
Low Noise / High Gain!  Time owned: 0 to 3 months
GaAsFet preamp with selectable (internal) 15 or 25db gain with less than .6db noise. I leave mine on all the time and if I need extra pre-amp I add the one in my 746 Pro. I have yet to open it up but will have pics of it on my site. www.ad5th.com It works great and also has a remote key line which works better than the rf switching for SSB work. It just sits there on the wall and works!
 


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