Question < > Answer beetween I1KFH < > S53MV

 

Q.

Can I substitute BAT14-099Rdiode withHP 5082-2831 ?

A.

HP 5082-2831 diodes are a low forward voltage, they are for low frequency and they are high capacitance diode (0.5pF), these diodes are not ok in my RTX. You can substitute BAT14-099R diode with 5082-2292 or 5082-2294.

 

Q.

Where do I find BAT14-099R diode? Can I substitute them with BAT15-099R type?

A.

You can find BAT14-099R diodes in Lubljana in some electronic component shop. For the substitution important are the diode capacitance (about 0.3pF) and high forward voltage (the schottky diodes are made with high, average and low forward voltage, the BAT15-099R diodes for example are at low forward voltage and they are not ok for my RTX).

 

Q.

On CLY2 gate (RTX 2.4GHz) I have a positive voltage, why?

A.

The CLY2 gate will never reach a positive voltage. A positive voltage means a bad connection of the CLY2, this is because you have exchangedGate with Drain. It isnít important, because in my circuit the CLY2 doesnít dead ... before to remove it, disconnect the power supply of the final amplifier transistor and check it with a ohm meter.

 

Q.

Can I use a CLY2 with a broken pin?

A.

The CLY2 in this case gives some less milliwatt, but it is ok.

 

Q.

I have in my shack antistatic foam already, like do I know if it is ok?

A.

You must check how many ohm you have at about2-3cm. distance in the antistatic foam. If you check 10-30Kohm, the antistatic foam isnít good. If you check some Megaohm it is ok.

 

Q.

In the2.4GHz rtx is critical the lenght of the cable from TX Mixer and front-end?

A.

In the 13cm RTX the cables donít have a critical lenght. I never had problems , but Iím not sure at 100%.

 

Q.

Are the HEMT very difficult to solder?

A.

I have soldered many hundred ofHEMT (not for amateur radio) and I never broke HEMT. In any case before to solder you must disconnect the power supply and other connections in your circuit.

 

Q.

The 2.4GHz RTX is not ok in rx, I donít have noise in loudspeaker and I donít have the CW tone when I switch in tx mode. I have checked the front-end and I have substitued the components: I donít know what to do.

A.

I think that you have exchanged base and collector of two BF199 transistors on the quadrature receive mixer.

 

Q.

When I power on the RTX in my shack, I listen an alternate noise in the loudspeaker, this donít occur when I am in portable (outside of my shack).

A.

The alternate noise problem is caused by a transformer near to rtx. You have to move your rtx from trasformer at about 1 meter distance.

 

Q.

I am checking the multiplier for 5184MHz (RTX 10GHz). I have power supplied only this module. I made these measures (at 12.6V and at 12V):

 

power supply module††††††††††††††††††††† 12.6V††††††††††† 12V

V beetween led anode and gnd†††††††† 1.72V††††††††††† 1.65V

V beetweenHEMT drain and gnd††† 1.44V††††††††††† 1.36V

led status†††††††††††††††††††††††††††††††††††††† much light†††††† little light

 

What is the right voltage on the leds anodes? My tensions are ok or not? The current drain of this module is about 165mA, is it ok? The 33 ohm resistor is very hot, can I install it outside the module?

A.

Your tensions are low, but they are okthe same. The red LEDs are made in two versions: the GaAsP leds give a voltage of1.6V, the GaP leds (the new type...) give a voltage of2V. Ok for 33 ohm resistor: it is very hot .... ! Maybe your transistors have an higher Idss of the ATF35376 type, did you useATF35176 or ATF35076?

 

Q.

I have used the ATF35376 transistors. My red leds are the old type. I thought to connect 33 ohm resistor outside the module because the entire module is hot!

A.

Ok, you can connect 33 ohm resistor outside the module .

 

Q.

Can I connect the two 10Kohm trimmers on the tx mixer of the 10GHz rtx outside of the module?

A.

Ok, you can connect the trimmers outside of the module.

 

Q.

I completed the construction of all RTX. On the small meter the output power response of the 2.4GHz rtx is very low, for the other rtx the output power response is fast. Why ?

A.

Your 13cm RTX is ok. So 23cm RTX should be the same, but the INA10386 donít have enough power to drive the CLY5 final amplifier. The two 5.7 and 10GHz RTX have a different project, without electrolitic in the gate, in this case the small meter responds more quickly Ö.

 

Q.

The 10GHz rtx has a problem on rx mode: it is very difficult to center the correspondentís modulation. When I tuned the correspondent and the modulation is good, ifI switch lsb or usb mode I always listen good modulation. As I exchangelsb/usb doesnít work. I checked the circuit with the 4029 and4051 and it is OK. Why?

A.

In your 10GHz rtx you have I or Q channel broken. Disconnect one or the other and you will find the problem.