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Author Topic: Ramsey kit amps  (Read 3834 times)
WM8E
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Posts: 15




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« on: July 20, 2012, 08:08:58 AM »

I am considering building a 40 meter Ramsey 20 watt amp. I would appreciate any comments good or bad from other Hams who have constructed them. I have read all the reviews . I would think coupled with the low cost and difficulty to find single band and cheap Amp for portable use that more folks would use these as a basic start with mods and upgrades to make a decent low cost portable Amp. Any comments or pictures would be appreciated. 73  WM8E
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K7KBN
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Posts: 2788




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« Reply #1 on: July 20, 2012, 10:17:11 AM »

What do you plan to drive it with?
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73
Pat K7KBN
CWO4 USNR Ret.
WM8E
Member

Posts: 15




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« Reply #2 on: July 20, 2012, 06:21:44 PM »

Pat; I would be using a R4020 Ten tec at 4 watts or perhaps a couple of watts out of my K1 Elecraft. I built a little 15 watt amp over 20 years ago and had $40.00 dollars in parts back then. I wish now that I would have kept it. Single band portable Amps are hard to find. WM8E
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AB7KT
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Posts: 155




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« Reply #3 on: July 20, 2012, 07:00:15 PM »

In reading the reviews on these amps a couple years ago, I burst into laughter.
I didn't post my review, but I was another person who built one and it went up in smoke.
Just as I put the finishing touches on my 40 meter amp, a ham friend happened to stop by. I said, you are just in time to watch me fire this up for the first time. Fire it up, I did. I had it sitting on the kitchen counter (yes, I was divorced), put power to it and whoosh, up it went in smoke with a little fire.

There are plenty of mods in the reviews to avoid this little problem but I haven't tried them yet even though I did buy another amp kit after reading the reviews and seeing some of the fixes they mention.
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I thought you said this was a weak signal mode ? I HAVE a weak signal and he still didn't hear me.

FWIW: My callsign is AB8KT
K7KBN
Member

Posts: 2788




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« Reply #4 on: July 20, 2012, 10:09:48 PM »

WM8E:  I've had generally good luck with the Ramsey kits I've built and played with.  That's not a blanket thumbs-up for all of them; AB7KT's experience might urge me not to go that route.  I was just concerned about the drive requirements for that particular amplifier.  Good luck!

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73
Pat K7KBN
CWO4 USNR Ret.
GM4UBJ
Member

Posts: 2




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« Reply #5 on: August 13, 2012, 03:40:39 PM »

Hi,
 I built the Ramsey 80 m amp a few years ago. I had a couple of issues with it.
1.. the heatsinks on the PA transistors were totally inadequate, I had to remount them on something much bigger.
2..The RF switch on board is a bit quick in going off..it drops out between words so I had to increase the size of the caps to slow it down.
I still use it with my qrp rigs and just change the low pass filter on the output when I use it on 5 megs.
Good cheap amp as long as you know its limitations..GM4UBJ
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W7AIT
Member

Posts: 488




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« Reply #6 on: August 14, 2012, 09:04:26 PM »

I built and tested the 20 meter Ramsey amp and never could get it to work, even after sending it back to the factory for repair and retest.  They said it worked after repair, but getting it back, it worked for few minutes then burned up.  I threw it in the trash.
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AD6KA
Member

Posts: 2237




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« Reply #7 on: August 25, 2012, 07:59:25 PM »

I built the Ramsey 20m amp with mods and
heavy heat sinks and it has worked fine for
almost ten year now. I am driving it with a
Small Wonder Labs PSK-20, and keep the power
throttled back to about 13 or 14 watts due to the
duty cycle of the mode. I have both boards
built into one enclosure with a small fan and it turned out
to be a spiffy little project. Most of the time
I run the PSK-20 barefoot (QRP) but can switch
in the Ramsey amp with a switch when needed.

A couple months later I built the 40m version
using the same mods and precautions and on first
power up .....WHOOSH it went up in flames.   Cheesy
Literally flames.
Go figure.

I would not recommend them to anyone.
I just got lucky.
If you want a nice QRP amp, save up your spare
change and get an HF Packer Amp. THree watts in,
40 watts out, operates 10m to 160m including WARC.

73, Ken  AD6KA
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