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QDX QRPpppp Mode

 

Hi QRP-Labs guys and gals,

I've recently built my QDX and so far made over 160 QSOs on FT8 and FT4 so, to me, everything was looking good.

Last night I borrowed from my radio club a couple of tuner units showing power and SWR. Using these I've now discovered the QDX is only TXing at around 200mW on all?bands (well bar 80 as I'm not set up for that). It's amazing that I've managed to log some USA and Russian calls on this amount of power lol.

I've removed the PCB from the enclosure and re-soldered some dodgy looking toroid connections around T2 (as this appears common to all bands) as could be seen under my magnifier, but the problem persists.

Does anyone have an idea on what I could check next? I'm a new Ham so I? only have a DVM and Nano-VNA for test equipment at this stage.

I'm using a battery pack, currently showing 9.8V on receive, dropping to 9.4 on transmit.

SWR is very good on all bands according to the meter(s) pushing into a linked dipole (when set for the appropriate bands).

It's got me stumped (clueless) at this point as to the cause so any help would be appreciated.

Robbie de M1ROK.
 

It's amazing that I've managed to log some USA and Russian calls on this amount of power lol.
Sometimes the elephant in the room is the answer. I suspect your power out is fine and someone has lent you duff test kit!?
What is your input current? For 5w output you should be drawing around an amp.

73 Ken g4apb?
n4qa at_hotmail.com
 

Congrats on your QRPp results !
At home, I typically run 12 milliwatts erp on 80 meters and am heard within about a 500 mile radius.
Here near the beach at Oak Island, NC, I run much more power - about three watts, all bands ! - to the amazing Miracle Whip antenna and work all over the eastern USA. :0)
Life can be a real struggle at times !
72 / 73,
Bill, N4QA/4
ps
Still pondering a QDX purchase...
 

Thanks Bill, yes it's amazing how far you can get on so little power. To the east of me I've reached Moscow, I believe, so this QDX design is at least strutting its stuff. I just salivate at what TXing at 4-5W would bring! ?Oh well, as the 74ACT08's appear to be as rare as rocking horse s..t at the moment, I guess I'll have to consign my QDX to the bin (what we in England call the trash.) Only jestin'; many thanks for your reply!

Robbie de M1ROK

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