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You simply did not scroll down on the join/renew page to find the member lookup which is there—I checked. And why post your problem on the tech list—with the caps button on? Preston Douglas

dID WE NOT HAVE A MEMBER LOOKUP ON THE HOME PAGE? yES, i FORGOT MY NUMBER. Did we take that function off the web? Mike Baker K7DD

Then the approach I'd take is try it... IT might succeed far more than expected. Allison -- Please reply on the group, no private emails we as a group get to share info that way.

Looking for something more durable and easier to heatsink. I never cared for heatsinking TO-92 devices (not effective in cooling the die) and three in parallel was never a favorite technique for me.

Why? Unlikely to give more power as its gain is lower than BS170s, If anything less power as you only can get so much from the 2n3904. It would be easier to heatsink and likely more durable. The

I was wondering about the use of an IRF-510 to replace the three BS170's. Other rigs use this device successfully. What do you think? I ordered the kit today. Randy.ab9go@... This message

Thanks for that explanation Allison. I'm not trying to fix a problem, I was just curious about the discrepancy in the resistor value, but it seems it's not critical and could just as well be a short

The 80185 board I have has 10 ohms but since its at the center of the balancing transformer it seems that its more or less odd to be a resistor at all and direct to ground. My Argonaut 505 uses a

Could some kind fellow-owner please check the value of R5 on the RF Power Amp Board (80185) in a TenTec 509? The CIRCUIT indicates TEN Ohms but mine is color-coded & measures ONE Ohm. No need to

Gang, Looking at the figures I posted earlier for the 40m output, they looked high compared to some earlier figures, and I have been unable to match that output or to account for the discrepancy. A

-- William, K6WHP "Cheer up, things could get worse..so I cheered up and, sure enough, things got worse!"

Not a thermal designer, but have considered best way to heatsink epoxy-molded parts like TO-92 BS170... On the one hand, the chip is bonded to the DRAIN pin, so some heat is efficiently conducted out

Its adequate until the battery drops to or below 11V and then the 7809 stops regulating. The 7809 needs more than 2V across it or 11V input to regulate acceptably. Of course then the only risk is

"...Setting the bias correctly is critical and using a stable bias source (its unregulated) will have the device bias vary with battery/power supply voltage.? A 5.1V zener across V1 variable

If one is running the BS170 as something close to linear the power out will be limited and heating is problematic. Since the to92 case and variants used have poor heat transfer ability adding

Hi Chuck, all In my opinion the BS170 is a great part. It is perfect for the QRP PA stage. They are very low cost and just perfectly placed to make an optimal QRP transmitter. By which I mean - if

Thanks, JT. Guess it's time to polish-up my ol' 'cheaters' :-P . Then Chuck's thermal tape might be the simplest solution. 73.......Steve Smith WB6TNL

Steve, From the 100219.pdf manual, the pictorial shows them vertical but the instructions still say to mount them against the board: "Q3, Q4, Q6 – These parts require some heat sinking. Therefore,

chuck adams via groups.io to have some heat sinking. Attached is photo of my solution." Good idea. Does the production board still have the copper fill area next to the FETs as in the photograph?

The QRPGuys new DSB transceiver requires the 3xBS170 FETs to have some heat sinking. Attached is photo of my solution. I used some 7mm wide heat sink tape that I bought off of ebay for cheap