VK Logger Ham Radio Forum Archive

Hi all...I have a new 144mhz amplifier for sale...This unit is built around a GS-31B triode in Grounded Grid using a 1/4 wavelength plate line tank circuit..It features both Tune and Load controls on the front panel..

The HT supply uses a custom wound Toroidal transformer, Voltage Doubled to produce 3300vdc..The amplifier has a 12 volt relay switching PSU...PTT can be activated manually from the front panel or via a remote switch line from a transceiver..Output relay is a Dow Key..Input and output uses N type sockets..
The amplifier uses a variable Bias controlled from the front panel utilising the reliable W4ZT Bias control board..All amplifier control functions are set out on the front panel making it user friendly and easy to operate..The amplifier uses two easy to read panel meters for Grid and Plate current..

Cooling is achieved with a 6 inch Papst fan operating from a 20vdc power supply...This fan produces more than ample air flow through the tube...The RF deck is sealed and pressurised...The air flows through the GS-31B finned cooler and exits the amplifier via a Teflon chimney...The Cathode compartment uses a smaller cooling fan blowing air over the Cathode/Filament of the tube and exits the compartment via vents on the amplifier case...

The amplifier has been extensively run and tested for reliability producing up to 1kw output SSB/CW and 500 watts continuous carrier..At these powers the amplifier runs cool...This unit is just coasting along at the VK 400 watt power limit and is suitable for EME work for those who hold the required High Power permit..

I have used all new components in this amplifier including the hand made case..The dimensions are 17 inches wide x 17.5 inches back and 12 inches high including the machined amp legs..The amplifier weighs about 26kg..It would be shipped via courier the transformer removed and shipped separately for safety..If you want full details or more pictures
I can be contacted by phone 0355791403 or direct by email vk3zl@bigpond.com ..

73..Bob..VK3ZL..

A thing of beauty

73, Roger Harrison VK2ZRH

Yes, another nice example from the VK3ZL stable.
And I note the 17" width of this unit should allow mounting within a 19" rack as well.

One of these, as well as a decent yagi, will set you up very nicely on 2m SSB.

Hi all....This amplifier is still for sale....Pics were taken at the SERG convention...

Bob..VK3ZL..

Hi again all..This amplifier is sold...Thanks to all for your inquiries..

I am currently working on a 70cm amplifier and I will have another 2 meter amplifier in a month or two..
70cm project is a prototype and I will post a few pics on the Logger soon.

Cheers Bob..VK3ZL..

Hi Bob,

Just out of interest, what sort of money does a handmade 2m amplifier such as this sell for?

73 - Rob VK2GOM / GW0MOH

Hi Rob It all depends on the amplifier makeup. I have sent you a list in a private email.. With the Aus $ falling nearly 10 cents below the US $, obtaining transformers, tubes and other parts plus shipping from overseas becomes more expensive adding to my costs..This is only a hobby/pass time for me to keep active and occupied in my dotage..I am over 70 years old...I actually get great pleasure building amplifiers..

Thanks....Bob..VK3ZL..

I must say a public thank-you to Adam for giving me some space in this forum to show my amplifiers..I will post details of some of my projects from time to time and invite comments and discussion...I am always learning and like to pass some of my limited experience on to others..Home brew is still alive although projects such as mine have a limited interest to younger modern radio amateurs..Playing around with high voltage is a serious matter and should never be considered without quite a lot of knowledge and at least someone around with experience..Building any project by hand including even simple kits will add to experience and the pleasure of seeing something that you made actually work..

Bob..VK3ZL..

Bob
You never cease to amaze me. Your commitment to the true meaning of this hobby is inspirational.
I have one of Bob's 6 metre amplifiers and it is one of my prized pieces of equipment, it is simple and robust and performs exceptionally well.

I look forward to following the progress of the 70cm version.

Regards

Shane VK4KHZ