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write your own review of the RAMSEY PR40 440mhz preamp.
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KF4ZMT
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Rating: 5/5
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Aug 19, 2008 07:58
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Outstanding Pre-Amp
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Time owned: 0 to 3 months
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My 14 year old daughter (who is also a HAM) assembled this kit for me. I use it for making LEO satellite contacts along with an Arrow antenna and Yaesu FT-60R and it works great. I did not find it necessary to bother with the Ramsey RF relay. I am only transmitting 5 watts and the MFJ duplexer I use sufficiently attenuates my 2 meter transmit signal on the 70cm side of the duplexer to avoid damaging the pre-amp. I'm very impressed with this product.
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WB1AAT
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Rating: 4/5
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Dec 18, 2007 11:34
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Very good for what it is
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Time owned: 3 to 6 months
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I built one of these for use with satellites. It went together easily and a phone question I had for Ramsy went answered quickly and clearly. For 15 bucks its a great deal and I will be using this as a RX booster for my outdoor use using a handheld antenna. Its not a SSB or ARR, but then again, these cost 4-10x more!
I got almost 4 S units improvement overall, but it definately amplifies the noise with the signal too. Put it this way. If you can barely hear it before, you can hear it better with the preamp, but it will still have prominent background hiss. If the signal is moderate, it will make it a strong signal. To my experience, it wont pull an unreadable signal thats in the noise out of the noise. It's just doesnt have a low enough noise figure to do that.
Some lessons learned though:
- it comes with no case, so you need to scrape up a small a shielded box to put it in. Perhaps PVC pipe if mounting outside. I used a small aluminum project box with a 9V battery and a switch.
- any RF into this will smoke the transitor. It only takes one time to pop it and I did it with as little as 1 watt. The transitor is cheap ($1.50) and easy to replace though and a good practice I use on my THF6 is to use the menu to inhibit transmit to prevent recurrences.
- the manual recommends a DPDT switch to switch it in and out of the line. If you want to protect the circuits (isolate both input and output antenna line) as well as switch the power, you need at least a 3PDT switch. This is how I did it.
Ramsey recommends the RFS1 RF Sense kit to prevent popping the preamp. I bought it but havent gotten around to building it. I May not actually.
All in all, a fun, cheap, and small preamp. But definately cant compete with the "big boy" preamps.
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VE6KJM
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Rating: 5/5
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Jan 18, 2007 15:09
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Excellent Unit
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Time owned: 6 to 12 months
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I built these for use with my homebrew yagi antenna on the LEO Sats, and they make the difference between hearing and not. I have used them on both FM & SSB and they work Great.
When you order them also order the RF detecting Relay as well as it is not WILL it happen but WHEN you key the mike with the preamp in-line and make it smoke. They are well worth the money. My tests shows about 16db signal gain with less that 1db noise gain because of the filtering designed in them. I have 2 sets of antenna, One set for transmitting the other set with Preamps that are used for listening.
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N8EKT
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Rating: 5/5
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Jul 9, 2005 08:07
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FANTASTIC!!
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Time owned: 0 to 3 months
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This preamp only takes 15 minutes to build.
Performance is fantastic.
Over 20db gain at about 1db noise figure.
I replaced a gasfet repeater preamp with this Ramsey PR40, and the Ramsey performed just as well and is 1/5th the price!
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