Showing posts from June, 2016

LDMOS Amplifiers

More on the control System ~ ( 7/05/2016 ) My initial thoughts on the switching of the low pass filters reflected on my past experience with filter switching harkening back to my KWM-4 SSB/CW transceiver built in 2013. When I built the KWM-4, this was a real challenge as my goal was to have no band switch as such; but rather to take advantage of a three digit code that could be associated with band memories that was generated in the K5BCQ kit. By using the encoder to menu change bands the three digit code associated with the bands could provide the signals to control the band pass and low pass filter banks. So why not the same here with the LDMOS amplifier?   Shown below are the BPF and LPF boards in the KWM-4.        Below is the KWM-4 schematic that was initially used with the project which was later changed to the second circuit which was finally used in the project. The second circuit uses P Type MOSFET's and in effect used less parts. For test purposes I in

Circuits on Hold

Making a Difficult Decision! I am placing a hold on any further LDMOS RF Amplifier postings. Frankly I have limited time and I must choose between blogging or working on the project. Thanks for riding along. 73's Pete N6QW

LDMOS RF Amplifiers

LDMOS Amplifiers --Are You On Board? 6/19/2016 ~ The Power of the Arduino -- The TR Switching Sequence. One of the biggest issues (maybe ranking near the top) are the problems with putting a RF Amp in line between your transceiver and the antenna system. All sort of problems can be encountered and mainly these revolve around protection of your precious FLEX6700 $8 Kilobuck transceiver to the issue of smoking the final. A one time permanent  tattoo that says "I Smoked a Final" is OK--but you want no more than one such tattoo in a lifetime.   So not only is it an issue of amplifier switching but amplifier protection! The Arduino is ideal in this case as there can be logic incorporated into the control functionality to add a high degree of protection.   Here are some possible cases that need addressing:   The Amplifier is OFF but you accidently pump RF into the amp. The Amplifier is OFF but you have the amp TR switches engaged so that RF is pumped into the a

Another New Transceiver from N6QW

Time for Another Transceiver! 6/13/2016 The 60M Arduino Sketch  code is now posted on Noteworthy is that the code includes the ability to auto switch the band pass and low pass filters depending on which button is depressed Pete N6QW 6/12/2016 ~ More Refinements I will soon post the code in .txt format on my website I am happy to report that I now have the capability that as you change  from the 60M channels to the 40M channels that signal outputs are available to change the Band Pass and Low Pass Filters. So there is automatic band switching which makes essentially the full operation follow what ever is punched in on the keypad. USB and LSB  switching is retained. Have received some inputs about eliminating the display entirely and by using 4 LED's the channel readout would be in binary format. Another suggestion was to eliminate the keypad and use the encoder to either act as a normal VFO or that it could have a mode to simp