At the suggestion of the AMSAT Treasurer I am posting this request to the bulletin board:
What I am looking for is a solid-state 70 cm linear amplifier that has an input of no more than 250 mW and an output of at least 10 watts and 25 or more would be even better. The frequency range needs to be from 432 MHz to 435 MHz or wider.
I am familar with a couple of kits including the one from Australia that definitely has the best price. However, I am also looking at building my own but have not found a suitable construction article here on the Internet using both "google" and "yahoo" as search engines. Nor have I found a suitable amplifier in the issues of Ham Radio Magazine and 73 Magazine that I have. What I am looking for is something that has a board "layout" (I am definitely able to reproduce a board). I do have a "fair" number of suitable transistors and other parts available that can be used.
Also, if someone has a suitable linear amplifier (this is for both CW and SSB) at a reasonable price or else for trade I would definitely be interested. I have all sorts of things to trade including tubes (receiver, transmit, higher power), components, and a few "boat anchor" items.
Since I am on a "fixed income" (Social Security disability) I definitely do have to be careful as to how much I spend on such things (my wife would definitely take severe action against my bodily health if I spend too much).
What I need the linear amplifier for is a Microwave Modules 432 MHz transverter. The 10 watt linear amplifier board is missing and the basic exciter only puts out 250 mW. Now I did know the amplifier was missing before I traded for the unit so that was not a surprise. The transverter works very well but the output power is not sufficient to really do anything with and is way too little to drive my 4CX250B amplifier.
Glen, K9STH AMSAT 239 / LM 463
Website: http://k9sth.com
----- Original Message ----- From: "Glen Zook" gzook@yahoo.com To: amsat-bb@amsat.org Sent: Sunday, October 12, 2008 5:07 AM Subject: [amsat-bb] 432 MHz linear amplifier
At the suggestion of the AMSAT Treasurer I am posting this request to the bulletin board:
<snip>
What I need the linear amplifier for is a Microwave Modules 432 MHz transverter. The 10 watt linear amplifier board is missing and the basic exciter only puts out 250 mW. Now I did know the amplifier was missing before I traded for the unit so that was not a surprise. The transverter works very well but the output power is not sufficient to really do anything with and is way too little to drive my 4CX250B amplifier.
Glen, K9STH AMSAT 239 / LM 463
Website: http://k9sth.com
Hi Glen, K9STH
I am using a transverter Microwave Modules MMT 432/28 S to drive my 4CX250B linear amplifier. If your original 10 watt linear amplifier board was missed I can send to you the schematic diagram of it and a picture showing how the components of it are placed over the PCB. Into the transverter board you already have a 250 mW driver stage with a 2N6256 or a CTC CD 3649 or a BL524 depending on the year of production. To duplicate the original power amplifier you need a 2N5944 a 2N5946 and two pin diodes UM9401 plus a 5 volt regulator. The rest of the circuit needs only few air trimmer capacitors of 5pF, 10pF and 27pF . The above power amplifier do not use a PCB with striplines but only 4 small silver plated copper wire air wound coils for the inductances so that if you are able to found the above active devices at a reasonable price you can use your skill to build the amplifier by yourself.
It is even possible that someone reading on this BB particularly here in EU hown an old and unused MMT 432/28 S transverter and send to you only the aluminum box with the 10 watt power amplifier in it.
What say ?...........someone please !
73" de
i8CVS Domenico
Thank you for the offer. I went ahead and ordered the 50 mW input and 30 watt output kit from VK5EME. There has been a pretty good increase in the exchange rate between the Australian dollar and the United States dollar in favor of the United States dollar in the past few days.
The price of the complete kit (including the power module) including air mail to the United States is $89.00 Au which is now $59.07 US. I decided not to take a chance on the US dollar going back down in value! Of course it might go up but $59 was a good price.
My 4CX250B 432 MHz amplifier is actually from an old Motorola 100 watt output FM unit. It works great for CW and all that I have to do to use it for SSB is to change the bias circuit. On 432 MHz operating CW it puts out an easy 150 watts and can do more if I increase the plate voltage.
Glen, K9STH
Website: http://k9sth.com
--- On Sun, 10/12/08, i8cvs domenico.i8cvs@tin.it wrote:
From: i8cvs domenico.i8cvs@tin.it
I am using a transverter Microwave Modules MMT 432/28 S to drive my 4CX250B linear amplifier. If your original 10 watt linear amplifier board was missed I can send to you the schematic diagram of it and a picture showing how the components of it are placed over the PCB. Into the transverter board you already have a 250 mW driver stage with a 2N6256 or a CTC CD 3649 or a BL524 depending on the year of production. To duplicate the original power amplifier you need a 2N5944 a 2N5946 and two pin diodes UM9401 plus a 5 volt regulator. The rest of the circuit needs only few air trimmer capacitors of 5pF, 10pF and 27pF .
The above power amplifier do not use a PCB with striplines but only 4 small silver plated copper wire air wound coils for the inductances so that if you are able to found the above active devices at a reasonable price you can use your skill to build the amplifier by yourself.
It is even possible that someone reading on this BB particularly here in EU hown an old and unused MMT 432/28 S transverter and send to you only the aluminum box with the 10 watt power amplifier in it.
participants (2)
-
Glen Zook -
i8cvs