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this is the 12th QDX i've built...
Receive is Hot Hot Hot..all bands..BUT
First time NO Power OUTPUT
Actually watching the current on the supply, it never moves from RX when transmitting,? And I expect there should be an increase.
Wired for 12v
so obviously checked all of L12, the finals,T2, L14 all good connections
looks like Q6 T/R switch works as well.?
I have almost 12v on the finals.
Where should I look first..

Vince,
You should see some sort of drive signal on the BS-170 gates during transmit. The drive signal comes from IC5. Have a look at the schematic.
If you have a DMM the voltage reading during transmit will be about +2.5 VDC. Using the terminal application's Transmit Test is probably the best way to test them.
Take care with the test probes! Don't short any leads together.

Test with 50 Ohm load on antenna connection. Does the LED flash when in transmit? PTT test working?

--Al
WD4AH

Al
thanks, I'll give it a test...and yes the LED flashes..

also 2.45v at all the BS-170 using Transmitter test..
so that seems good.
v

looks like a bad solder connection at the center tap of T1..
Power out now..
thanks for the hint of the IC5...should have spent some time at the schematic..

These toroids get a lot of people.??

Pretty low power out...around 2.5w..across all bands.? I usually get over 5w with 12v... ;=((
ugly signal i think at the Finals (have a scope)..should have looked at one of the good ones that I built..
v

Vince,
Sorry to hear that you having the issue. If you're still getting ~2.5 Volts on the BS-170 gates and you have the 'scope then you should check to make sure they are getting driven with square waves at the operating frequency.

If the drive signal looks good than it almost has to be one of the BS-170's. Since 2 FET's are connected in parallel it's hard to tell which has failed; you might be able to tell with your 'scope which 2 of the 4 are 'bad.'?

I would probably help to make sure all T-1 connections are good and solid. If you do pull all 4 FET's before reinstalling them check the gate drive signals to make sure they're about the same, just out of phase.

Good luck!

--Al
WD4AH

Since

Al,
Thanks, I've pulled the FETs...I'll check later.

?

V

Found that T1 Center tap was not soldered well enough.
Thanks Al,
I've scoped around some to see what it should look like if i run into any other no xmits..
Got a good handle on it....should have just looked at the schematic..

73
Vince