Here's one that caught my eye:..attached
ARRL handbook 1968 pages 187 - 190
Single 811
I'd like to 'keep' my homebrew "as is"...with only the necessary internal changes.
That should be no big problem...esp since the power supply would be external.
And...I'd like to use the 'smallest' power supply as necessary....'small' in cost as well.
And...I really don't need much QRO
Firstly, you *REALLY DO* need much QRO if you go to the trouble of adding a linear amplifier.
1-Your transceivers are capable of 80-100 watts output on CW and SSB
2- the maximum output from a single 811a at 1500volts on the plate is about 150-175 watts including feedthrough power.
That means that- at best- you are getting 3dB more signal.
3- 3 dB is insignificant in terms of actual signal at distance
4- The minimum increase that is useful is 6dB (4x power) which is one S-unit.
This means that the threshold for justifying an amp is 4x 100watts = 400 watts output.
5- You can get 400-450 watts from 3-811a.
Finally- if you ever want to be successful at building anything, you should:
1- Read about amplifiers and understand a little about how they work, including high voltage power supplies and input and output matchung networks.
2- read articles on well designed amplifiers using the tubes you are considering.
4x811a amps are easy to build and relatively cheap, if you look for the parts pm EBAY and trade threads on Ham sites or tap into the really generous hearts of old timers who love to help a you g guy willing to work hard and do it right.
3- Ask guys who have actually done it and if you do not understand, ask more questions.
4- Think about it and plan your project
A. Accumulate parts-it might take a year- be patient and keep at it.
B. Make a schematic and a parts list and get what you need
C. Plan the physical layout- it matters, because it affects stability and
and performance.
D. Measure three times, cut once- chassis are expensive to destroy without
thought.
E. Seek help all the way to assure best practice in the details. Vast experience
lives here.
Failure to plan and educate yourself is not only prone to fail, but with high voltages, it can kill you.
Read the story of Icarus the Greek who preceded the Wight Brothers by 2500 years, but less successfully….😉
It us an interesting thread and you have received good advice, but failure to follow some method like I have outlined is just churning words and goes nowhere.
Follow it and you will be amazed at what might be accomplished.
A lot of us built a knowledge base in Ham Radio that powered our engineering careers. Be assured, it came with much effort and a lot of failures along the way, but grit and never give up attitude succeeds every time. Decide which road you will take and follow your dream… MB
