OM8AQ

Let's not look for mysterious Windows complications there, where they are not. I had the same problem some time ago. You need to set the virtual COM ports in the file for the appropriate one “PRETEK.CFG” in TR4W and in the TR4W program menu Settings-> RIG settings, CAT a portu CW->RIG1 tak, so that they do not collide with each other. T.j. do not use the same COM port number for different two functions. The obvious thing is, that the serial baud rate on the radio and modem must be set the same, including the correct type of radio. The functionality of the communication between the TR4W software and the radio via modem can be verified via the appropriate modem software. If you use microKeyer, there is a CAT line under RADIO in the introductory window: with the appropriate port, followed by the text “open” with information of the set transmission serial speed and the number of transmitted bits and stop bits. When I press the SET box on the right, serial-level communication between the radio and modem opens. If the course of the communication report is smooth, is everything OK. If the statement jams, has time breaks, is a problem and the above needs to be addressed. CW fields: a PTT: have the same port number, but different from CAT: All other fields are None.
73, Stano OM8AQ,

Norbert, my answers and questions are:
1. It makes no sense to put two Pi cells in series. I don't understand the information: “In the 80m band, I looked at the SDR receiver, the harmonic level decreased quite a bit after the addition of the second instance.” Which harmonic is it? ? If it is basic, i.e. the first at 80m, no wonder. It is much more interesting to measure the level of the second and other harmonics, whether the higher amateur radio bands are not disturbed by unwanted radiation.
2. Please explain in a sentence “There is a 1A@11V outlet and the output is only slightly higher than the 49er.” which means “49is” ?.
3. Bridge PSV meter for QRP is fine, but cannot measure output power.
4. If the core of the coil in the Pi cell is heated, it is clear, that either the impedance of the final stage is not matched to the impedance of the antenna and a substantial part of the radiated power is converted to heat in the coil and in the final stage as reflected power, or that the ferromagnetic material of the coil core is not suitable for KV – has too high magnetization losses at the operating frequency.

Stano OM8AQ

If this scheme http://prekladatelia.info/chinesekit.jpg current, the answers are as follows:

A. Behind the output stage transistor Q5 is a Pi cell formed by C17, L4, Q18, which matches the impedance of the output stage to the impedance of the antenna. Its tuning is as follows:
1. I will place a mA meter in the upper end of L3.
2. I lock and slightly change the capacity of C18 (upwards, or down) to the minimum current to the collector of transistor Q5. At the same time, I measure the output power to the antenna. It should be the largest at the minimum current.
3. I will slightly change the capacity of C17, e.g.. upwards. It increases the current to the collector of Q5 and the output power drops. I change the capacity of C18 like this, to find the minimum current to the collector of Q5 again. If, after setting the minimum, the power to the antenna is lower than it was at the point 2, I will change the capacity of C17 in the opposite direction, that is, to a lower one and I repeat the fine-tuning to the minimum current with C18. This is how I continue by gradually changing the capacity of C17 in the right direction and fine-tuning C18 to the minimum current, which correspondingly increases the power to the antenna. I will finish setting up the Pi article, when I reach the limit current of the output transistor Q5 (maximum permissible with regard to the current cooling and transistor parameters), which should correspond to the maximum possible power to the antenna. It roughly applies to this connection of the final stage, that the transmitted power to the antenna is about half of the current collector loss.

B. Choke L1 and capacitor C8 form a low-frequency pass. They prevent the penetration of the RF signal into the NF amplifier. An inductance of 100mH is fine, 100uH is not enough – probably a printing error.

C. The diode in the base of the final transistor serves to trim the negative half-wave of the excitation voltage. The output stage in this connection operates in class C and the negative voltage on the base transition – the emitter could break it.

D. The oscillator in the NE602 is a classic and popular connection of the Colpitts oscillator.

I wish you success in experimenting.

73, Stano OM8AQ