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I think Jerry has a much simpler idea -- just find a way to disconnect the gate bias during receive. This would put the gates at 0v, and effectively shut off the IRF510 drains. Probably a good

Like this: Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois Owner – Operator Villa Grand

In the case of the uBitx and Bitx40 we use the IRF510 FET's to turn off the PA power by shutting down the gate bias voltage source during receive. Drain current should be zero.

Post it here or on FB if you accept Paypal.? I bought a uBitx off a fellow ham that was in the same boat.? 73, Michael KM4OLT

Hello For power conservation it is possible to use a power FET to turn OFF voltage to the RF PA section during receive mode. Turn the switch device on with +TX power and off when this goes to

The FET's are more linear with a high quiescent current. Though the WA2EBY gets away with 10ma quiescent drain currents into the IRF510's which is a considerably less linear device than the

Thanks for your help Chris and your feed back, -- Regards John 2E0Eii

Thanks Marco for your reply a big help

Un solder the smc resistor and fit a higher wattage resistor to the top of the PC it will do the job chris g0wfh

Hi John, It is a double sided board. I would just remove the resistor and put in a 1/2 watt in its place. Also, check the transistor (Q14) to make sure it didnt sacrifice itself also. Good

Hi Guys can you give me some help i have popped R141 ,whilst working a station near Inverness who gave me 5/8/9 , Then Smoke !! luckily R141 let go , I would like to replace with a bigger value

Nick, Did you ever post the sketch for the TPA2016 AGC? Aug AG5AT

Thank you all for your kind words and valuable feedback. I will then leave the idle PA current near 500mA per device despite the current drain. I have contemplated adding some series

Well if you look closely there is some reactance at high frequency in the gate circuit to compensate for high capacitance loading at higher frequency. Thats a real tight rope to walk though because

?Didn't realize he has L3 in there. I have the boards and parts somewhere and may eventually get around to building it! This would form a series circuit (to AC ground) with the gate-source

The WA2EBY amp has also been simulated, including notes on what those inductor values are: ? ??/g/BITX20/message/41269 Somehow WA2EBY managed to get good performance without any

Gordeon, please have a lok on the "famous" WA2EBY amp. He is using inductors in series with teh gate-bias resistors. My explanation is that this inductor of unknown value together with the gate-souce

Farhan is actually referring to Mitsubishi transistors. See this message posted earlier today for some information:?/g/BITX20/message/41910 -- Karl Heinz - K5KHK

That 40% drop explains a lot. I would still like to see that confirmed by test. It could also be compensated for on board to keep the drive level flat. Dr. William J. Schmidt - K9HZ J68HZ 8P6HK

If you elect to set a reserve price, be warned that it turns off a lot of potential buyers and therefore will not bid. I usually just set a starting price for about the lowest I would take and let