All solid-state HF/VHF/UHF Amp Stack Plans

[AD7N]

I'm doing some long-term shack planning for amps, and wanted to share what I've got so far. I'm pursuing an entire solid-state amplifier stack for HF/VHF/UHF

HF: Communication Concepts EB27A. 2-30Mhz, 300W out with ~10W drive.
http://www.communication-concepts.co...s/eb27a-4.html

6M: RFHam.com 1KW amp kit using Freescale MRFE6VP6IK25H MOSFET
http://rfham.com/index.html?p219.html

2M: W6PQL RF 1KW deck using MRFE6VP61K25H MOSFET
http://www.w6pql.com/parts_i_can_provide.htm

1.25M: W6PQL 1KW kit using MRFE6VP61K25H MOSFET
http://www.w6pql.com/parts_i_can_provide.htm

70CM: W6PQL 1KW kit using MRFE6VP61K25H MOSFET
http://www.w6pql.com/parts_i_can_provide.htm

The Freescale MRFE6VP61K25H is my choice because of the minimal 2-5W drive requirement, bullet-proof nature, great power efficiency at peak (70%) and very cheap compared to similar KW commercial amps.

My estimate for the entire stack above, including additional safety components is around $3-4k.

[KD0CAC]

I am gone to have to check some of that out , but a little light in HF .
Looks good and they are kits

[WB2WIK]

The Freescale stuff is very interesting and Klitzing has been making amps for a very long time, so hopefully they're pretty robust.

For permanently connected systems (amps feeding big outdoor antennas), especially in any area that might be prone to lightning, I'd prefer tubes at that power level. I remember when I lived in NJ years ago it was common that I'd be operating right through a lightning storm (contest or whatever) and if the amp is connected to the antenna (TX mode) during a near strike, everything in the way of SS amps would almost always fail; the 8877s and such just kept on working fine.

Not having to repair expensive stuff is a big benefit, to me; but it all depends on your application and where it will all be set up, etc.

[AD7N]

The Freescale stuff is very interesting and Klitzing has been making amps for a very long time, so hopefully they're pretty robust.

For permanently connected systems (amps feeding big outdoor antennas), especially in any area that might be prone to lightning, I'd prefer tubes at that power level. I remember when I lived in NJ years ago it was common that I'd be operating right through a lightning storm (contest or whatever) and if the amp is connected to the antenna (TX mode) during a near strike, everything in the way of SS amps would almost always fail; the 8877s and such just kept on working fine.

Not having to repair expensive stuff is a big benefit, to me; but it all depends on your application and where it will all be set up, etc.

Thunderstorms are always a very real hazard of course. The Freescale chip is insanely robust - they advertise it can handle a 65:1 SWR, which indicates to me it's "good enough" for most what I need
Of course there's other components on the RF deck that are less robust, but I'm less concerned with caps or similar as those can be cheaply replaced.

My main use will be as a base radio amp, but they're also going to see a lot of mobile or even camping use potentially. I'd rather not have to worry about bumping one the wrong way and cracking an expensive tube. A completely solid-state amp can handle a few more Gs

[AD7N]

I don't know how much experience you have with these kinds of "kits" but this is what I had learned over the years.

Thank you for a first rate reply. I'm basing my buy based on two eHam reviews that indicate their particular EB27 "kit" isn't ultra hard, but not Elecraft-easy either. One of them also mentioned the necessity for very accurate drilling, but also mentioned the instructions supplied for the EB27 were good. I'm not an extremely experienced kit builder but patient enough to make one well.

[AD7N]

If you look at the picture you will see an eb27 board and a mrf422 which is the transistor used in that "kit". That kit is what I spent a year trying to stabilize. It isn't inherently stable but good luck. So far I have built and moded about 25 of these amps over the years along with many 12 and 50 volt versions of essential the same amp design with kits from CCI.

I did not realize this, good point. I need to think how I want to do this first, and your experience is a good benchmark for reference.

[K9FV]

Since you are looking at having 50volt power supply for the VHF/UHF stuff, why not consider a 50 volt MOSFET amp? MUCH better performance - and cleaner. There is a guy selling assembled boards on ebay that are neat and well built from what I can see. He seems VERY knowledgeable on these type amps. His complete boards less MOSFET are a good be less than CCI offering for HF, and MUCH more complete. I have ordered the copper heat spreader and heatsinks from CCI. There are MUCH better sources for 300 watt HF amps, but why not place for at least 500 watts on HF? Here is the link to the ebay seller. http://tinyurl.com/ctkbp3t

Have fun and enjoy - I might suggest starting with a single small amp before buying several of those amp "semi-kits".

73 de Ken H>

[AD7N]

Since you are looking at having 50volt power supply for the VHF/UHF stuff, why not consider a 50 volt MOSFET amp? MUCH better performance - and cleaner. There is a guy selling assembled boards on ebay that are neat and well built from what I can see. He seems VERY knowledgeable on these type amps. His complete boards less MOSFET are a good be less than CCI offering for HF, and MUCH more complete. I have ordered the copper heat spreader and heatsinks from CCI. There are MUCH better sources for 300 watt HF amps, but why not place for at least 500 watts on HF? Here is the link to the ebay seller. http://tinyurl.com/ctkbp3t

Have fun and enjoy - I might suggest starting with a single small amp before buying several of those amp "semi-kits".

73 de Ken H>

Great advice, and good link! Running everything from 50V makes the most sense, particularly when dealing with high amperage power supplies.

I think my progression will start off with buying a good, "portable" 50V power supply and then one of the above-mentioned amps to play around with first. I've never ran anything above a 100W before so I need to get my feet wet with working at the KW level.

[WB2WIK]

For high-quality, robust and inexpensive 50V power supplies, the used telecom market is a great place. Most of those supplies are actually 48V and positive ground (if either rail is actually grounded), but can be used fine in 50V negative ground applications, usually, even if that means electrically isolating the chassis (usually not required).

Since they're all switchers and designed to work under some rather horrifying conditions, they're really good and usually work over a very broad range of AC input voltage (at least 90 to 140V, or 180 to 280V for the 240V-powered ones) without missing a beat. Many also have robust transient protection as part of the design.

I bought a surplus telco 48V 50A power supply made by MagneTek years ago for $75 and it worked perfectly.

[AD7N]

For high-quality, robust and inexpensive 50V power supplies, the used telecom market is a great place.

Perfect! first stop for shopping for the project