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Author Topic: Cost of Building an HF Amplifier?  (Read 2224 times)
G3RZP
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Posts: 894




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« Reply #15 on: February 11, 2019, 04:45:18 AM »

You can often get given parts. We (G4FNC and myself) got two vacuum variables as wedding gifts.......
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LA9XNA
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« Reply #16 on: February 11, 2019, 02:07:22 PM »

You can look for a "Donor amp" and use that as a starting point.
This will give you many of the components required to get started.
The most important is probably the voltage and amps on the HV transformer to fit with the tubes you plan to use.
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W1VT
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« Reply #17 on: February 11, 2019, 04:08:43 PM »

Cockcroft-Walton cascade may not be suitable for typical SSB operation with its high peak to average ratio.  Similarly, the pure tone of traditional CW may be hard to achieve with a cascade.
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MM0IMC
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Posts: 195




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« Reply #18 on: February 12, 2019, 04:11:55 AM »

It's difficult to know where to start, as I've a fair collection of Russian NOS valves to choose from.  Roll Eyes I've got a GS35B, a couple of GS31B's, a couple GI7B's and a GI46B.

I've been advised in the past to stay away from microwave oven transformers. I do have ten Chinese 450V, 220 microFarad electrolytic caps I could use. I've also got a separate transformer that would be good for use as a heater transformer and would easily accommodate the largest Russian valve.
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PU2OZT
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« Reply #19 on: February 12, 2019, 05:35:36 AM »

CW cascade may not be suitable for... CW...

That was a good one I sure remember when taking my Extra
 Grin Grin
Oliver
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N8FVJ
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« Reply #20 on: February 13, 2019, 06:20:55 AM »

I suspect some used amplifiers would be cheaper than the cost of building a new amplifier.
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WA5VGO
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Posts: 63




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« Reply #21 on: February 13, 2019, 07:22:55 AM »

It’s not all about cost. It’s also about pride and the learning experience.

Darrell
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K3UIM
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Posts: 287




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« Reply #22 on: February 13, 2019, 09:51:40 PM »

Amen, Darrel, although I'm thinking not too many of todays hams are doing very much building. (Mores the pity!)
Seems that back in the 50's and 60's we didn't have the necessary bucks to do a lot of buying so learned to enjoy the thrill of building and learning.
(Judas Priest! I'm aging as I type!!) Hi.
Charlie, K3UIM
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Where you are: I was!
Where I am: You will be!
So be nice to us old fogies!!
N3DT
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Posts: 1537




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« Reply #23 on: February 21, 2019, 06:39:48 PM »

Building a good amp from scratch would be a huge project and fraught with lots of learning. If you want to do it, go for it, but be prepared to spend more than you would for a new one and lots more time than you expect. I've thought about it, but just couldn't, I bought a perfectly good 80B for $900 and found other stuff to do. I'm not sure learning how to build an amp is useful at this point in time, other than for the satisfaction and bragging rights. I've seen some really nice homemade stuff though. It's not for everyone.
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WA5VGO
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« Reply #24 on: February 22, 2019, 07:42:16 AM »

Building and experimenting is the essence of the hobby. How can anyone find satisfaction passing a test that 10 year old kids can pass and then operating a bunch of store bought appliances? How can someone with an extra class license justify purchasing a manufactured dipole or paying someone to install a microphone connector?

If the only objective of the hobby is simply to communicate, just purchase a computer or cell phone. With almost any hobby, the objective should be to continuously push your skills and knowledge.

Darrell
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MM0IMC
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Posts: 195




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« Reply #25 on: February 23, 2019, 10:32:57 AM »

Building and experimenting is the essence of the hobby. How can anyone find satisfaction passing a test that 10 year old kids can pass and then operating a bunch of store bought appliances? How can someone with an extra class license justify purchasing a manufactured dipole or paying someone to install a microphone connector?

If the only objective of the hobby is simply to communicate, just purchase a computer or cell phone. With almost any hobby, the objective should be to continuously push your skills and knowledge.

Darrell

I don't consider myself to be a dope with a soldering iron, having built a few things myself, having repaired my former Ameritron AL-811H and done countless microphone plugs for others. Wink  It's just building an amplifier from scratch is a magnitude of difference to what I've done before and a far more expensive! Shocked
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K6AER
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« Reply #26 on: February 24, 2019, 10:17:37 AM »

You can obtain a lot of the parts from MFJ, Harbach, transformers from Tran-X in Colorado Springs.

For knowledge you might want to repair a few used amplifiers (Grounded Grid) until you see how and why tings are done is a certain way.

Many amplifier control assembles can be bought from various hams. Most material and boards being offered are for solid state designs.

You will never be able to build one for the cost of buying a well working used amplifier.

As others have  said the knowledge is priceless.

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AA4PB
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Posts: 14860




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« Reply #27 on: February 24, 2019, 10:44:04 AM »

There are certainly advantages to building your own tube type amp such as knowledge gained, pride of good workmanship, etc. However, the new solid state amps offer many advantages such as:
1) No tuning required. Instant band change.
2) instant on.
3) Microprocessor monitored and controlled. The processor monitors voltage, current, heat sink temperature, power output, and SWR. If anything goes out of spec then the controller either reduces power or cuts off the amp in order to protect it from damage. The processor controls fan speed so noise is minimized by setting the fan speed only as high as needed to keep things cool.

I've built a few amps (home brew and kits) since my entry into ham radio in 1959. However, when deciding it was time to get another amp recently I decided that it made more sense "for me" to purchase a solid-state amp.

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Bob  AA4PB
Garrisonville, VA
W1VT
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« Reply #28 on: February 24, 2019, 01:04:59 PM »

But, those are valuable skills. You could expand on those skills to design a phased array that monitors the current in each element.  As well as other specialized functions that can't be affordably mass produced.
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K8AXW
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Posts: 6997




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« Reply #29 on: March 03, 2019, 11:43:27 AM »

The pleasure of building an amp is one factor that should be factored in the "cost!"  As a builder of a few amps from 20w SS to 1500w hollow state, may I suggest:

1 - Pick a circuit you consider "buildable."  (Complexity, not one of a kind part, etc.)
2 - Create a list of parts required.  This part is half the fun of amp building.
3 - Start your search for the parts and keep a record of where and how much.
4 - Add it all up and if it falls within your price range start acquiring the parts, which includes  sources mention by several others here.
5 - Start the planning where everything goes so you don't start the  metal work only to find that there isn't room for the parts!
Don't hurry.  Building one of these things takes planning and work that you don't want to do over and over and this  is where the fun is.  Not the actual operation!  Have fund doing it!













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