VHF Amplifier..

VK3ZL Amplifiers
Post Reply
VK3ZL
Forum Novice
Posts: 40
Joined: Wed Sep 14, 2011 11:34 am

VHF Amplifier..

Post by VK3ZL » Mon Jan 20, 2014 4:36 pm

Hi all, I am currently using up some spare components to build a new VHF amplifier..This may be the last unit I can build for some time...Due to the low Aus$, importing new components have suddenly become expensive and I may have to add the cost to any new amplifiers I build after this unit..

Pics are a new "vacant" amplifier case and a GS-31B triode...If anyone is interested I can build this up as either a 6 or 2 meter amplifier...This will be suitable as a legal limit amplifier, or for use as an EME amplifier for those who have a high power permit...It should be good for at least 600 watts data,800 watts CW or 1KW SSB..The amplifier will be the same build style as those shown on my Logger page..

I can be contacted via email or phone 0355791403...

73...Bob..VK3ZL..
Attachments
HPIM5907.JPG
Amplifier case with Papst fan and GS-31B tube.The Papst fan is a 12-28 volt unis rated at 285CFM free running...The air pressurises the RF deck and exits through the tube cooler and a Teflon chimney on the top cover..Under pressure there is more than adequate air for this tube...I use a multi tapped transformer so that voltage can be selected for more or less air pressure.
HPIM5905.JPG
Another case view...The case is built using anodised aluminum..I clean the anodising away from all metal to metal joins in the RF deck so that there is good metal to metal contact..

User avatar
VK6OX
Forum Diehard
Posts: 294
Joined: Thu Mar 20, 2008 7:08 pm
Location: Perth NoR OF78vd

Re: VHF Amplifier..

Post by VK6OX » Wed Jan 22, 2014 10:29 am

Looking good Bob! 8)

Another fine example of your excellent amps in the making! :D
73
Andy VK6OX

If you can't explain it simply, you don't understand it well enough. Albert Einstein

VK3ZL
Forum Novice
Posts: 40
Joined: Wed Sep 14, 2011 11:34 am

Re: VHF Amplifier..

Post by VK3ZL » Sun Mar 02, 2014 6:42 pm

I have taken lots of time off due to illness however I have finally finished this amplifier and it has been sold..This amplifier was 2 meters with a 1/4 wavelength plate line output...Everything tuned perfectly at first switch on..With 25 watts drive it has in excess of 500 watts output and runs cool...The air flow noise is quite low using the 6 inch Papst fan running on 15vdc..Drive vswr through the T network is 1-1.I am really pleased with this amplifier and will pack it and send it to the new owner this coming week..This amplifier can be operated remotely via a PTT switch line.

I am hoping to complete the GS-35B 70cm amplifier soon along with my own small two band, 6 and 2 meter amplifier..This uses GS-9B triodes and will be loafing at 300 watts output..

The Australian dollar is staying around 90 cents and I now have to pay a lot more for importing tubes and transformers..This means that I have to add a few dollars on to my amplifiers ..I am currently having some health problems but I am anxious to return to my workshop..

73...Bob..
Attachments
HPIM5921.JPG
HT power supply...This uses a 1350kva Toroidal transformer voltage doubled..
HPIM5912.JPG
Simple 1/4 wavelength plate line with link coupling on output..
HPIM5915.JPG
Front panel hinges down for access to Step start, Bias system and 24 volt relay supply.
HPIM5916.JPG
My standard front panel layout..Plate and Grid meters, Bias set control and PTT etc..

User avatar
VK2ZRH
Forum Diehard
Posts: 933
Joined: Mon Apr 09, 2007 2:17 pm

Re: VHF Amplifier..

Post by VK2ZRH » Sun Mar 02, 2014 6:44 pm

Beautifully done, Bob. An absolute credit to your engineering nous and craftsmanship. :D
73, Roger Harrison VK2ZRH

User avatar
VK6OX
Forum Diehard
Posts: 294
Joined: Thu Mar 20, 2008 7:08 pm
Location: Perth NoR OF78vd

Re: VHF Amplifier..

Post by VK6OX » Sun Mar 02, 2014 8:07 pm

Wot Roger said above ...^ 8)

As a proud owner of one of Bob's VHF amps, I can only marvel at his efforts in producing such fine and AFFORDABLE devices.
My 6m 2 x GI-6b PA from Bob continues to perform exactly as Bob had designed it....robust and over-engineered for reliability. 8)

Thanks again Bob and well done!! :D :D
73
Andy VK6OX

If you can't explain it simply, you don't understand it well enough. Albert Einstein

VK4KHZ
Forum Diehard
Posts: 206
Joined: Sat Jul 26, 2008 11:05 am

Re: VHF Amplifier..

Post by VK4KHZ » Sun Mar 02, 2014 8:44 pm

And Ditto.....

Get well soon Bob...you have plenty more of us to inspire!

Regards

Shane VK4KHZ

VK3ZL
Forum Novice
Posts: 40
Joined: Wed Sep 14, 2011 11:34 am

Re: VHF Amplifier..

Post by VK3ZL » Tue Mar 04, 2014 12:10 pm

VK4KHZ wrote:And Ditto.....

Get well soon Bob...you have plenty more of us to inspire!

Regards

Shane VK4KHZ

Thanks for the kind words Shane..I am looking forward to doing another project soon..

Bob..VK3ZL..

VK4WTN
Frequent Poster
Posts: 157
Joined: Thu Jan 14, 2010 4:45 pm

Re: VHF Amplifier..

Post by VK4WTN » Tue Mar 04, 2014 7:10 pm

Hi Bob, best wishes for your health, theres a few more amps in you yet. My 2 x GI7B amp is working like a dream
best wishes Wayne VK4WTN

Post Reply