VHFcontesting
[Top] [All Lists]

[VHFcontesting] 222 MHz Amplifier Project UPDATE for CSVHFS Conference

To: "vhfcontesting@contesting.com" <vhfcontesting@contesting.com>
Subject: [VHFcontesting] 222 MHz Amplifier Project UPDATE for CSVHFS Conference
From: David Olean <k1whs@metrocast.net>
Date: Sun, 23 Jul 2023 09:56:38 -0400
List-post: <mailto:vhfcontesting@contesting.com>
Hello VHFers

I am bringing a few completed 1500 watt 222 MHz amps to the Central States Conference in Little Rock. If you were interested in getting one of the amplifiers,  I wanted to let you know that some of them will be at Little Rock.  That is this coming weekend.  It looks like I will have at least five of the 11 units all done.  (N1AV is working on two amps as well in AZ. That makes a total of 13 amplifiers for 222 EME and meteor scatter) The other remaining units are all close to complete. I just ran out of time. I wanted to get some amps done and distributed in the western parts of the country, hence the road trip to Little Rock!

With all the mods I did, adding TX sequencing for external relays, and protection circuits to protect the FETs. I have put in about $350 of cash into each unit. (You can't believe how much even the small stuff costs these days!!)  After much discussion, the consensus was that some minimal amount should be charged  to insure that the new owners would be somewhat serious about using the gear!  The price is set at $700 for each amp. This is rather obscene for a 1500 watt amplifier and is less than 50 cents per watt.

Here is a picture of the almost completed 1st unit.  There are RCA jacks on the back for keying and sequencing of TX relays. The front panel has some LEDs to let you know what is happening.  One shows DC power, one is for TX, and the remaining two are VSWR faults and high temperature faults.  There is an AMP ENABLE switch on the front panel as well.

The picture of amp #1 is below. I had no labels on it yet, and the wiring was not 100% complete in this picture. My plan is to also have an abbreviated manual for the amps. That will happen very soon, but they are not going to be ready for this coming week.


All you need is a 48-50 volt supply and a TX relay. All the rest is done. A directional coupler and low pass filter is on the output, and a W6PQL ultimate control board is installed to monitor faults and provide sequencing.

I used a smaller amp version on 222 MHz last week and ran 500 watts on battery power. WZ1V has another of these amps in the 500 watt version, and he loves it.  They basically just sit there and pump out RF!!  At some point this fall, I will have two more 500 watt amps converted. They have the same characteristics and W6PQL boards as the 1500 watt versions.  All this is to generate more 222 MHz activity on EME and meteor scatter so that achieving WAS is easier. There have only been 18 222 MHz WAS awards issued since the band came in use.

I am leaving for Little Rock at 2 AM after the next 222 MHz activity night.  I hope to arrive in Little Rock on Thursday. This is exciting!


73

Dave K1WHS

ps. I had some help from a few folks to make this project move along. A big Thank You to the following who helped with the project:  N2CEI at Downeast Microwave, W6PQL,  W8ZN at Directive Systems & Engineering,  N0AKC, and WA1T. I hope I did not miss anyone.
_______________________________________________
VHFcontesting mailing list
VHFcontesting@contesting.com
http://lists.contesting.com/mailman/listinfo/vhfcontesting
<Prev in Thread] Current Thread [Next in Thread>
  • [VHFcontesting] 222 MHz Amplifier Project UPDATE for CSVHFS Conference, David Olean <=