Re: #bitx40help BITX40 LSB Winlink #bitx40help

Timothy Fidler

JM there is a whole lot of information here around this BBS in various corners.  see right down bottom of this post...
(public version of post sent privately a while back) 
Extra filters can come from Kees Talen who sells little PCBs for this purpose .  Moto appn note AN267 is  your friend for this design.  KT sells parts .. you do the design.

you will need to change out the IRF PA for a  proper Mitsi HF or VHF Mosfet. The pinouts don.'t align as Flowers found out but he worked out a kludge - eg wiring the RF transformer direct to the drain of the RDHH16.  The fact that the  Source and tab on the RDHH16 and 15 Mosfets are the same simplifies some of the rework and of course makes heat sinking a lot easier. Those Mosfets are avail at reasonable prices as in just over 5 usd plus freight from "cecil the parts place". DIZ,  the toroid king used to stock them but > more.

  There is a V2 version two that involves hardware mods- BEWARE.  Best have a backup plan like a second Raduino or a clone so you can always fall back to plan A.   is a new load of software that may do many things you want. It also contains a whole lot of fixes and includes CW capability.

In terms of display for both 40 and 20 m with a dual band design (??)  this item (search for 6 digit freq counter) from might solve your problem $13 USD without a recode job. you use the frequency counter in native mode to display frequency in 20m operation and the original Bitx display for 40 m operation  (sounded like a good idea at the time ).

Type 43 material is pretty lossy above  7 Mhz.(can forward data) there are magnetics which if you change  them out will make a difference.   Flowers got 6W out he says with only the Mosfet change.  Without that change he was getting less than 2 W out.

MOtorola design note AN267 is your friend for  designing the New output filter.  (Kees supplies parts not designs)
With six watts you can drive plenty of amps that will give you 50W+  out

Just The guts of this amp come up from time to time on Ebay as just PCBs all ready to go but no case  for region of $80 USD. It uses an MRF-186 dual RF mosfet  ..beware imitations esp beware of SMPS mosfet kits .  Crude as hell but it works and is hard to kill it seems. Somebody in PRC obviously lucked into a whole lot of surplus Motorola parts at bargain prices

There are some reviews of it on Austr. websites./blogsites 

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