Re: KNQ10 (sort of) fixed, more help needed

Adam Rong

Hi Jon,

Is the MOSFET marked V11? The RF output is quite sensitive with power supply voltage, so if you can supply with 13.8V, you can get much higher power I believe. Another hint is that you need to tune VCO output for each band by tuning the trimmers on the digital board. If you have done so, please forget it.

The reason why I am talking about these, is that your RF output is still lower than expected, so even you replace D882 with C1971 or C2166, you still cannot get enough power you want. C2166 should help but the pinout is reversed with D882, so you need to study how to solder them very carefully.

73 de BD6CR/4, Adam

On 2011-9-12 1:25, iapizloj wrote:

it turned out that a MOSFET was wrongly placed. Once fixed I am able to get (at 12.0 V) about 7 W on 80, 2 W on 40, 1 W on 20 and 60 mW on 15 meter. I have read that there is a mod for the KN-Q10A, replacing the audio transistor 2SD822 with a 2SD1971 for a higher gain at higher frequencies, in order to fix low power at 21 MHz.
The 2SC1971 is a VHF (175 MHz) transistor with 10 dB gain and 6 W output power. I can get locally 2SC2166, which are HF (30 MHz) transistors with a higher gain (13.8 dB) and same power, 6 W.
Is the Ft characteristic something essential for this application?
Maybe somebody has a good advice on this. Any hints appreciated.
jon, ea2sn

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