Problem with IR Receiver/Transmitter 455 kHz (rec. TSOP7000)

Hi everybody. I'm working on some project with IR communication between transmitter, which is oscillator on 455 kHz with cmos nand gates and receiver TSOP7000. Datasheet for IR diodes and TSOP7000 claims that range of even 20 meters can be achived, but i get only 1m, where is output of receiver stable for sure.
For transmitting i've been used various type of IR diodes: TSHA55xx, TSHA62xx, VSMF3710 (smd), all from Vishay Semconductor. Response of them varies from 10ns to 600ns. And, they all give the same result, small range. On oscilloscope i've watched signal from the output of cmos nand gate and it looks fine. Output of mosfet is not very well, but i think that can do the work. Rise time edge is about 600ns. I've tried to replace BUZ11 with IRF540 which is faster, but there is no improvement.
If someone can help, i would be very greatfull.
Best regards.

Didn't look at the schematic ... But ..

What is the ir Freq of the TX diodes ?
I seem to remember the 455Khz TSOP's were 840nm or at least different from the standard 940nm.
How much forward current are you putting through the TX diodes (Look at the pulse current in the DS),
And you do have remembered a 100nf , and prob. 10uF cap accross the RX TSOP ?

/Bingo

Added after 11 minutes:


Had a look at the schematic.

Are you sure you can drive a BUZ11@455Khz from a single 4011 gate ??

Have a look at the input of the FET with a scope.

You do have the possibility to add the last 2 4011 gates to get 3 in parallel , to drive the fet.

/Bingo

Most sensitive wavelength: BW3dB of TSOP7000 is 820-970nm, with a center of ca. 870nm!
On that (and by 300mAmp!) is given a <=20 meter transm. distance...
You can see that explicit with TSHF5400 & 870nm.

Please refer to the TSOPs datasheet, side 3:
The (data) burst length should be>=22us, but<=500us!
Between two bursts separate with min. 26use!
If data bursts are >500us, your duty cycle can be max 25%!

You can see on datasheet of (for ex.)VSMF3710;
If Tp/T =0.2-0.5_the max Idiode ~30-70mA..., but if it is less 0.06, it can be up to 200mA...

YOU MUST HAVE some Rlimit in serie with your diodes too_in other case you will kill there!
Your IR-diodes has ca. 10V and practiacally zero Rlimit-only the drive capability of your power supply sets some limit:-(.
If you have a external Rsource for ex. 1.0-10 Ohms (as wrote bingo600 too) you can measure/monitor the Diode currents too.

CD4011 can drive max. at +/-3mA and nomore modern family, not for new designs!...
Select 74AC00, OK; is not pincompatible, but has better ESD protection & is a actuell component.
Than IRF540 has Cinp, at 3nF, Idrieve capability of up to 120Amper(Rdson is max 77mOhm!)...
Buz11 is a little bit lower power(Cin at 2nF typ, Rdson max 40 mOhm), but similar.
K.