Termination Insensitive Amplifier with AGC: Time to Upgrade your BiTx?
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- čas přidán 11. 11. 2021
- The experiment to give Wes Hayward's (W7ZOI) Termination Sensitive Amplifier an AGC prompted Wes to do a re-think of this iconic amplifier design. Here, Wes' famous modified amplifier block is prototyped. Could it be time to upgrade your BiTx or uBiTx transceiver with a true, IF-based dynamic gain stage?
Termination Sensitive Amplifier with AGC, by Wes Hayward W7ZOI:
w7zoi.net/tia+agc.pdf
My original experiment:
• AGC-controlled Termina...
My original blog post:
vk3hn.wordpress.com/2021/08/0...
TIA on Soldersmoke:
soldersmoke.blogspot.com/2021/... - Věda a technologie
Interesting, I need to learn more about this to fully understand. Thanks for taking the time to make the video.
Glad it was helpful! Thanks for commenting.
Thanks Paul! I love those Wes Hayward TIAs and now I've got the workbench up and running again I might have to give this new design a whirl. Glad you'll be able to get out and about more freely now. Enjoy! 73 Nick (M0NTV)
Hi Nick, good to hear you are settling into the new digs, look forward to seeing some more video stories from you. Your two videos on filters are excellent, a vital topic and skill that gives you more success with homebrew radio the better you get. The crystal filter video should be a reference for many builders for years to come. Keep explaining things, it's a skill that people need and not everyone has. 73 Paul VK3HN.
@@Paul_VK3HN Thank you so much Paul - you're very kind. 73
Hi Paul...
AGC is a difficult point...thanks to give this special infos about it...73
Yes it's not to be underestimated, particularly in simple analog receivers. Thanks for your insight!
Great idea. I downloaded the paper and started to build it many thanks de 2e0ree
Let me know how it works for you.
Many thanks for sharing. I completely missed this new paper (sadly there is no RSS feed or anything). I did some experiments with variable gain amplifiers as well recently and shared some results on my website. As it turns out it's relatively simple to get ~20 dB of gain rage with a good impedance match out of two feedback amplifiers, and the design process is quite straightforward. These amplifiers are not termination-insensitive though.
Hi Alex, thanks again for commenting. If you watch the Soldersmoke Daily Blog you can pick up a few leads like this, along with lots of interesting posts.
I read your experiments on variable gain bipolar gain stages on eax.me -- a fine summary of controlling emitter degeration to vary gain. I tried this on a Termination Insensitive Amplifer stage, and it worked very well, however it messed up the input impedance making the gain stage into just an A, not a TIA!
As always, there are a number of ways to do this kind of thing. The TIA is such a useful gain block, and being bi-directional can simplify transceiver switching as you well know from your projects! I am still a big fan of the dual gate MOSFET (or its equivalent in the form of a cascode bipolar/JFET pair ) for gain, noise figure, AGC range and predictability, and ease of construction.
73, Paul VK3HN.
nice Paul , i have a few questions ...but first...i have one experimental receiver with Pete n6qw Plessey bilateral amplifier and i m interesting can i conect TIA AGC between OUTPUT of bilateral amp. and input of crystal filter....????sorry my englisg is bad :)))))))
Hi Mladen, I keep telling you, don't apologise for your English, I don't speak a word of yours! You probably could put the cascode JFET and bipolar pair after an existing TIA for more IF gain and some AGC gain control, but watch the impedances, and you may end up with too much gain ahead of the filter. But as always, worth experimenting with. 73!
@@Paul_VK3HN thanks Paul, the pcb is ready and i Will try for few days