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Jerry, I would suspect the measuring instruments. If you have an oscilloscope, then parallel up 20 of 2 watt/50 ohms resistors as a dummy load and measure RF voltage (with bandwidth filter on our

Do you think this is the cause of the amp failing, or damage caused by the amp failing and sending some rf back into the radio? Max KG4PID

All, To help me post-mortem the Chinese linear, I was checking the output of the uBITX on various bands. I used a Bird 4410 wattmeter with the 10kW slug ( which can be switched down to 10W full scale

Yay! This also means that we cant do away with the post mix amp altogether... Maybe. We need 80 db of usable, distortion free range for good measurements. Let's see how we will get there. With 14 dbm

I was WN6EPS. It was a nice call - dit di-dah-dah-dit di-di-dit! The other day, I QSO'd a guy who was running a pair of Conar twins. Sounded just like the old days...Bwee bw-bwee-bwee-bwee. Chirps &

Birdies?? I've been a ham for over 50 years.? In one of my very early days I worked a WN---- (don't recall the rest of the call). The signal sounded like he couldn't find a key, so he was pulling

Hi John, Well, it was coincidentally on 80M when it died. And that is surely the band on which the uBITX gives the most output. But if that's enough to fry the finals, the amp and the uBITX are just

BLF861 16 BLV861, 20 available BLF278 6 available SRF3943 6 available SRF426 (Mrf426)? 4 available MRF150 gone MRF314 4 available MRF148 gone MRF450 2 available SD1480 gone

All very fair points.? I clearly misinterpreted an intention that wasn't there. You're right, it was.? I latched on to one word and ran with it.? As long as you're having fun with your radio the

*** Unsoldered the final transistors - one of them tests as a MOSFET, the other one as a 1.8 ohm resistor. I'm guessing the latter is the bad one :). There is another Chinese amp that uses a real RF

Jerry, Did you measure the input impedance to the changed low pass filter before you applied power through it? It might not present an impedance that makes the transistors happy. Also, given the

Hi Doug - no offense intended. QRP is fun. That's what ham radio is for - for me, anyway. Fun. But it's no fun when people don't hear you. And at my QTH, with my antenna, people mostly just don't hear

Discussion of amplifiers of modest size (50-100w) is pretty common across several large QRP mail reflectors I subscribe to, it came across here as little more than a playful jab. As I recall, Ashar

*** Doubt it. That package is used only for dual RF devices. But the device could be used/surplus, or failed-QC. And the amp I'm looking at uses a device that's characterized at 850MHz. The fact is,

I am assuming your intention was not to insult the 7,101 other members of this list that find QRP very useful.? However, if you don't like your QRP gear you could probably sell it and added to the

I wouldn't bet on that, a large percentage of 'RF Transistors/FETs' out of China are faked. -- https://www.vk5tm.com

Jerry I used to recommend that you set the bias pots for minimum current and then slowly increase one pot to increase the idling current by 100 ma, then increase bias on the other MOSFET until it

To make it easier, BLF861 20available. BLV861, 20 available BLF278 12 available SRF3943 6 available SRF426 (Mrf426)? 4 available MRF150 4 available. MRF314 4 available MRF148 2 available MRF450 2

Sorry, that is a 12V part, the transistors I have are mostly commercial use with 28/32V or 48/50V

Farhan and Chris, With the GALI-6+ still in place (it's U2, after the first mixer), adding a 6 dB attenuator between the generator and Specan caused the distortion product to fall 17.9 dB.? But the