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Author Topic: 630 m PA Construction Notes  (Read 439 times)

VK6HP

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630 m PA Construction Notes
« on: March 10, 2020, 02:38:34 AM »

One of my recent projects was a FET power amplifier for 630 m, based on the push-pull 300 W RF module produced by G0MRF.  A particular aim was to have a fully integrated amplifier, with all power supplies and other circuits in the same cabinet.  Having finished the PA, it occurred to me that some of the construction and component sourcing approaches may be of interest to others looking to build a 630 m system.  I've written some notes which are available at http://users.tpg.com.au/adslif89/ph/vk6hp/MF_amp/VK6HP_630m_Amplifier.pdf and pasted a peek of the partially-unboxed PA front panel below.

73, Peter.

« Last Edit: March 10, 2020, 02:44:13 AM by VK6HP »
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K3UIM

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Re: 630 m PA Construction Notes
« Reply #1 on: March 16, 2020, 08:30:48 PM »

Peter,
As a retired tool-maker of 33 1/2 years, I see the skill and effort taken on your project!! Congrats! I'm thinking you have/had your share of metal working tools. Great layout. Beautiful!
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Charlie. K3UIM
Where you are: I was!
Where I am: You will be!
So be nice to us old fogies!!

VK6HP

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Re: 630 m PA Construction Notes
« Reply #2 on: March 16, 2020, 11:36:47 PM »

Thank you Charlie, that's very kind.  I freely admit that while I've been blessed with a good eye, the hand sometimes lets me down.  And, as an engineer, I have to concede that the concept can be better than the execution. The good thing about ham radio is that there's something to keep us all honest.

I don't have a lot of tools or a very big shack/workshop and I therefore tend to spend a lot of time (perhaps too much) thinking about simplified construction techniques and ways of hiding less than perfect cutouts etc.  More than likely someone with your background would just hop in and have the job finished while I'm still thinking.  Regardless, the good news is that the PA is going well and, with a bit of decent propagation this southern hemisphere winter, it should help with the 630 m results.

73, Peter.
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KM1H

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Re: 630 m PA Construction Notes
« Reply #3 on: March 17, 2020, 09:46:35 AM »

Excellent work Peter and Charlie, when are you going to build me a cabinet? Im mostly a sawzall and hacksaw guy for metal.  Plus a chainsaw is my preference for wood :o

Carl
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VK6HP

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Re: 630 m PA Construction Notes
« Reply #4 on: March 18, 2020, 12:28:07 AM »

Carl, what I could really use is a "big boy" Dremel.  My small Dremel clone has been pushed into metal working acts that no Dremel should be subjected to and I keep thinking it'd be so much easier with, say, double the power and size.  I keep meaning to see if anyone has solved the problem.

73, Peter.
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W9IQ

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Re: 630 m PA Construction Notes
« Reply #5 on: March 18, 2020, 04:44:39 AM »

Peter,

A beautiful job on that cabinet.

You may enjoy looking at some of the computer controlled X-Y router designs on the maker sites. They have them for wood routing, paper cutting and metal cutting. They are generally built from off the shelf components or 3D printed parts and controlled from a PC running free CAD software.

- Glenn W9IQ
« Last Edit: March 18, 2020, 04:51:53 AM by W9IQ »
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

VK6HP

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Re: 630 m PA Construction Notes
« Reply #6 on: March 18, 2020, 07:28:56 AM »

Thanks Glenn, but do bear in mind the cabinet itself is a commercial instrument case, per the construction notes.  The suggestion of the makers' sites is a very good one and, indeed, one of my colleagues suggested participation in a local makers' group.  I don't have any experience of these groups but apparently the knowledge sharing works pretty well and, from a purely practical point of view, I see they have some nice machines (which could no doubt be used in conjunction with designs such as those you mention).

73, Peter.
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