Hi again,
i just looked at the eneloop batteries.
So I calculate with estimateed data. 2000mAh capacity, 90% charge after one year.
This means 10% discharge in 365*24h = 200mAh / 8760h = 22.8 uA
This is 2280 times the bjt current.
Klaus
Hi,
i don´t think it is a good idea. Any change in antenna, direction, distance, transmitter power (bad battery?) may lead to wrong switching.
To make it more secure, i´d go for sending data (UART style). A small (maybe 8 pin PIC or AVR) uC can
* check if code is correct (to prevent wrong switching at all)
* decide to switch ON
* decide to switch OFF
And low RF power should be no problem.
That´s a more intelligent solution, but also a higher effort solution. And it needs additional power. With intelligent sleep and wake up it may be low enough.
Klaus
In your schematics you use MMBT2222.
The datasheet says: I_EB0 (Emitter Cutoff Current) = max. 10nA.
(that equals to 300 MegOhms resistor, that might be in the range of flux residuals)
Hi,
Mmbt4401 datasheet,
Look at figure7. This is the current when V_BE = 0.
Klaus
We both read the same...Just to confirm I am reading this right. Is this 0.4-0.5nA at 25C?
;-)So now you could say "It is not zero". You are right.
Hi,
We both read the same...
from my post#19:
;-)
Klaus
The antenna is an active rubber antenna for those V/U TX portables that have HF RX coverage.
Why do you create a complicated switching solution, instead of a simple passive diplexer? That would route the RF range to the RF antenna, and the VHF/UHF range to the VHF/UHF antenna. Simple hardware, no manual switching needed, no power supply needed.
I have to say I do not understand the question. The whole point is to have the RF switch power to the preamplifier and bypass it and at the same time this circuit must consume no power when no switching action occurs (to save battery life).
However the schematic on post #24 works without a diplexer and it is much simpler and does not require a dual band transceiver at all, so it is more general.
(Note on your dualband comment: I didn't suggest to use dual bands for switching your relay. I suggested to use no relay at all, and separate the RF bands passively with the diplexer. The only disadvantage is that your RF preamp would be always ON, consuming power. )
Well, you have a trend towards the most complex solutions for the most simple problems. A much more elegant solution would be to power (and switch) the setup through the coax cable, with a simple bias tee at the antenna cable.
That doesn't require a modification to the transceiver, avoids battery use and avoids the crazy operating scheme of transmitting to switch the receive range.
I think you have not understood the situation, unless I am missing something.
As explained in previous posts, the active antenna is a rubber antenna that is used on top of a handheld V/U transmitter with a wide (HF) RX coverage.
How would you power the antenna without modifying the transceiver? Batteries must be contained inside the antenna and the antenna has to be switched from the transmitter signal (thought it to be more elegant and low profile than using a hand switch on the antenna).
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