开云体育

Hi
I've just ordered a BITX40 and looking forward to using it.
Just wading my way through all the great info on here but would like
to ask what mods I should be doing first off once I have the rig running.

Thanks for any suggestions for a BITX newbie

Phil? G4JVF

At a minimum, the function button. If you're into CW, then, of course the CW mods.. You must do that one. I have all the mods in mine except the latest stuff related to the capacitance keying. All are simple enough to do. Most folks replace the standard tuning pot with a 10-turn; that doesn't require any other mods and makes tuning a lot better.
--
John - WA2FZW

Thank you John.....will look into those


Phil? G4JVF

IMHO there are two mods that are required, everything else is just added functionality.?You need to add a capacitor to limit 2nd harmonic emissions, and a couple of diodes to protect a transistor.?

Both mods are described here:?



These two mods are required even if you want to stay with the original Raduino firmware. Once you switch to Allard's firmware, then?the function button is the first mod you need to access all the additional functionality, but chances are you want to do more (e.g. remove to caps to enable USB mode). Take a look at?Allard's documentation, he talks about what changes are necessary for what functionality.?

73,?

Karl Heinz - K5KHK

All noted..
Thank you Karl

Phil? G4JVF

On Fri, Oct 27, 2017 at 04:51 am, John P wrote:

At a minimum, the function button. If you're into CW, then, of course the CW mods.. You must do that one. I have all the mods in mine except the latest stuff related to the capacitance keying. All are simple enough to do. Most folks replace the standard tuning pot with a 10-turn; that doesn't require any other mods and makes tuning a lot better.
--
John - WA2FZW

From your link, it appears that there's a plan to include the 2nd harmonic fix in the build from hfsigs.

Any idea if or when that will happen?

Apologies if I missed something.

I'd certainly recommend adding the cap to suppress ?the 2'd harmonic,
especially if going QRO somehow. ?A 100pf cap is a very cheap and easy fix.

Though as Don Cantrell notes, the stock bitx40v3 is very close to legal:
??
A 5 watt transmitter that's 3db into the red will have a second harmonic
that is just as strong as a 10 watt transmitter that is just barely legal.
And much weaker than the typical 100 watt rig.

A harmonic that is 40db down from the carrier on a 5 watt rig has a power level
of 5w/(10**(40/10)) = 5w/10000 = 0.5 milliwatts

So fix it if you have not yet done so, but I wouldn't be too concerned
about nasty letters from the authorities wanting their license back.