开云体育

ctrl + shift + ? for shortcuts
© 2025 开云体育
  1. BITX20
  2. Topics

Working on my 2nd V2 sBitx

 

3 of 6 upgrades done
?
1. ?Added “send” optocoupler output
?
?
2. 180 ohms in drain of Q101 (protection)
/g/BITX20/wiki/36110

3. 470 ohms in series with D20 (protection)
/g/BITX20/wiki/36110
?
3 more upgrades to go on this nice V2!!
?
?
?
 

Thanks, Gordon,
I have a working V2 and have started doing upgrades. I appreciate all your information on this.
George VY1GP
 

Attached is a final document with a list of the reliability-improvements and photos of how I managed to put them in.? ?Amazingly, I didn't break anything!? ?It appears to work just fine afterwards.? ?I have one of the 64-bit setups working and thanks to some help, I can compile this also!? ?
?
  • I have not yet checked the potential reduction in receiver birdies from the aluminum foil shielding of the display cable.
  • I'm away from normal home and don't have a good 50-ohm dummy load so no reliable power output measurements so far, but appears to be at least as good as the previous V2 IRF520 replacement that I did.
?
(Data from the other replacement I did on the previous unit:? from post: /g/BITX20/message/115243 )
?
IRF520? Infineon? ?biased for about 0.3Amp total idling current
3pf TVS diodes on gates instead of the previous huge zeners (which Ashhar says don't stop the problems)
MODE = CW? ?Power measured by Siglent scope and mathematically voltage -> 50 ohm power
Frequency? ? 100% drive output power? ? hw_settings.ini? ? Comment
3.5010? ? ? ? ? ? ? ?32W? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? .0037? ? ? ? ? ? ?Gets a little less power than on 40, similar setting to IRFZ24N
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? my earlier notes suggest I got a little more power than this, with the IRFZ24N's
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? and gate zeners, so the IRF520 may be a little inferior here.
?
7.010? ? ? ? ? ? ? ? ? 33.3? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?.0028? ? ?
10.1? ? ? ? ? ? ? ? ? ? 22.6W? ? ? ? ? ? ? ? ? ? ? ? ? ? ? .0028? ? my notes indicate I was in the range of 21W with IRVZ24N & gate-zeners
14.01? ? ? ? ? ? ? ? ? 16W? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?.0032? ? my notes here on IRFZ24N don't make sense
18.1? ? ? ? ? ? ? ? ? ? ?9.33? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?.0061? ? ? ? ? ? ?? the gate circuit reactance issue here?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?notes indicate I got 11-12W with IRVZ24N's
21.01? ? ? ? ? ? ? ? ? 16.6? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? .0054? ?notes indicate I could only get 15W with IRFZ24N & gate-zeners
24.9? ? ? ? ? ? ? ? ? ? ?12.3? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?.0063? ?notes indicate I could only get 10W with IRFZ24N & gate-zeners
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?likely due to their huge capacitance
28.0? ? ? ? ? ? ? ? ? ? ?11.52W? ? ? ? ? ? ? ? ? ? ? ? ? ? .0063? ?notes indicate I could only get 8W with IRFZ24N & gate-zeners
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? likely due to their huge capacitance
?
Without a dummy load, I made some initial measurements and adjusted the coefficients on the new unit and on several bands came up with very similar coefficients, suggesting that the circuitry and devices are performing reasonably similar.? ?I think I'm getting in the range of 40W on the two lowest bands, at around 12 watts on 10 meters.? ?These numbers are quite adequate for me!? ?I like having the additional robustness against excessive drive that the TVS diodes may bring, and the additional robustness against SWR-issues, that the 100V (drain-source limit) that the IRF520's give.? ?(Ashhar selected the IRF510 for the V3 with the same drain-source voltage capability).? ?Be careful to buy 520's from reputable sources and there are versions out there with inferior specifications.
?
73
Gordon KX4Z
?

sBitxUpgrade.pdf
sBitxUpgrade.pdf

 

On Tue, Mar 18, 2025 at 10:44 AM, Gordon Gibby KX4Z wrote:
I have not yet checked the potential reduction in receiver birdies from the aluminum foil shielding of the display cable.
It does not reduce the number of receiving stations, but it significantly increases the sensitivity that can be adjusted with the sensitivity control, which is also visible in the waterfall.
In the unshielded state, it started to get noisy above 50, with shielding this level shifts to around 80.
?
--
Gyula HA3HZ

1 - 4 of 4