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The BC637 shares a datasheet with the BC639. The BC639 seems to be exactly the same except for a slightly higher voltage rating, it is available. So not a mystery that the BC637 would

Hi, I'm selling due to my changed workload a recently arrived, unopened box of BITX40 with Raduino for $59 +$10 shipping to US and Canada. Estimated delivery time is 3-5 working days. Offering it

As a means of protecting the IRF510's, I think a polyswitch in the PA-PWR line should work great. The IRF510's mostly fail due to overheating, a small polyswitch will have far less thermal mass then

Im glad you are happy with them, See my blog for a few photos, https://vk4pln.blogspot.com.au/ 73 Nick

Thank Jerry, but I am standing on the shoulder of giants. Yes agree about the applications, and I like your idea of changing the mixer unbalancing from the first to the second IF stage to get the

Yep! They work slowly, need a current limiting resistor to allow the polyfuse to reach cutoff temperature before the protected device fails.? Again, slow... Ki4PSR

I want ?to duplicate the small audio amplifiers at?https://ludens.cl/Electron/audioamps/AudioAmps.html but he uses a BC637 & BC640 pair. They have the BC640 at mouser but NOT the BC637. What should

Very clever, and very cool! Much of what you have figured out could be applied to other attenuation schemes.

Got some pretty good results with limited memory usage to flatten the power curve, but only in voice/digital modes (SSB). I use the first IF shift to produce a fixed attenuation to keep the output

?fascinating. Thanks!! learned a lot. ________________________________ Sent: Tuesday, April 10, 2018 8:34:47 PM To: [email protected] Subject: Re: [BITX20] AGC circuit to try? So back more years

So back more years than I care to count, I designed and build my first receiver. That is when I first learned how to build AGC circuits. I did a lot of research… At that time most of the leading

Nick VK4PLN. your Boards showed up today. They look very good. Now to build a couple up. Thanks again! Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ Owner

If you access the list from?/g/BITX20/topics there is a search function.? Here's the last discussion?/g/BITX20/topic/7489182 regarding polyfuses and other

Depends what you are trying to protect... It's as good as a slo blow fuse. Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ Owner - Operator Big Signal Ranch –

Hello Jerry, Tried both methods and came back to your idea..hihi The lookup table (four frequency points, plus interpolation) does the job better. For info about the si5351 clock updates, the chip

Fine and useful research Jerry. Thanks. 73, John (VK2ETA)

Tried to open the new uploaded .sch file in Eagle. Message says start missing. Is Eagle the correct program to open this in or was another program used. Thanks Rick KN4AIE

They are better at higher frequencies.? However at lower HF it may be problematic. The 1N4007 is fairly slow and makes a terrible rectifier at 10KHz, I tried them years ago for a LVSMPS to go from

Thanks to Don ND6T and Gary AG5TX on the insight of why there is a feed back thump on receive when the condenser mike is bumped. I have added an extra resistor and a 2n7002 MOSFET? to clean up the

Hi Ian Just to let you know that my straight key behaviour has now improved out of sight with v1.061, which is fantastic. I was finding that different keys behaved differently and could be unreliable,