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But now you really should tell us what is, Mike.You have us all curious.

Bill VK7MX

On Wed, Jun 6, 2018 at 04:15 pm, Doug W wrote:

I am running a totally stock rig

I need to correct that.? I am running a totally stock board.? I have changed the audio pot to fit a knob I wanted to use and have added a fan to cool the irf510's even though Ashhar, the ?BIT's designer, doesn't think it is necessary as well as changing the LCD for a white on black one and using a non stock mic/ptt jack.? If anything my haste in responding and the other responses pilling up show you how many of us are very happy with this radio.? Build it, you will like it.
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A mistake, sorry.? Went to group when I meant to send it to myself.

Mike, WA6ISP

I am lost here, what is this.
--
Allen ?Merrell

-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

This little radio is many, many times better than what I used as a novice. I'm having a blast with it. Put it together and be amazed?
Dan, W2DLC?

Seems to me the time to decide if you should shoot it before you pull the trigger.

IMNSHO for a little over $100 it is a steal.? I am running a totally stock rig.? It is the first ?BITX version sold.? Lately I have been operating mostly digital.? In just over a month I have hundreds of QSO's, I have worked all continents except for Antarctica, I am one state short of WAS and have many 1000 mile plus per watt contacts.? So will it work?? I tend to think so.? Don't let all the mods and improvements scare you off.? This is a very active community with many interests.? Build it stock to start and I bet you are happy.


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On Wed, Jun 6, 2018 at 06:37 am, Gwen Patton wrote:

?

I ordered that EF01 enclosure from Banggood, so someday that'll arrive, as well as the 3d printed front and back plates on eBay. (Yeah, pricey, but so what? Saves me the time and effort to drill stuff.)

I haven't put much effort into marketing but there is an option other than the guy on ebay for panels?/g/BITX20/message/50308 .? I went with a much more minimalist design approach.? Of course if you are like most of us you are going to want to make changes after your first build and will end up cutting, drilling and melting anyway.? Also while shielding the case is certainly a best practice many have gotten away without doing it.? I am not recommending (or admitting to) one way or another.
?
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One of the factors not reported was the consistency of the gain vs spur. Simple put
the gain and the spur interacted even when I held the level to the mixer constant.
I'd lower the gain and the spur would get worse as an example.???It varied?
greatly with supply voltage as well.

Reason sluggish 3904s (low FT, Maybe Low? HFE).? Remember we are using a
300mhz device and that is a typical value and can be as low as 250 (batch and
vendor) or much higher.? I changed them out for BFR106 (Q20, Q21, Q22), Seems
the 3904s were not up to the task of keeping the amp load independent.?

The net result was what others had reported as lower spur production, in mine it
dropped the 10M spur nearly 12db.? So it was either distortion in the? 45Mhz amp
or its ability to be a low output impedance which should be with emitter follower
with the 47ohm making it look near 50 ohms.? I didn't? try 2n2963A as I didn't
have any left in SMT but I suspect they would have been better.

For now I'm taking a break on output power and addressing other things.? The
power thing stands at 10W at 80m, 7W at 10M with the spur 46db down.??

I'll list all the changes as my unit stands while I do pop/click and mod then agc.

For now mods I have in place, I'm not 100% happy but that is what
us experimenters enjoy.? Likely others to come. ;)
?
Replace and reset bias OF Q90 with 2n2369A or better (BFR106),
Set bias for 18ma (r86 2.2K).? Make C81 470pf, and r83 8.2ohms.

Change C82 to 470pf (peaking for 10M).??

T9 is now 9 turns #28 bifilar (one winding was never used).

All the 2n3904s in the predriver and driver replaced with 2n2222A or better.
Hint I mounted them on the underside with very short leads as it makes
the top less crowded.??

Driver amp has 2.7uh SMT choke in series with R86 and that is now 1.6Kohms
R87, r88 Both have a 270PF cap in parallel with them.

R911,r96, R941, R942 emitter resistors for driver reduced to 11ohms (add parallel 22ohm).
R92, R95 replaced with 1.5K ohm in series with 2.7uh choke.? (resets bias and adds peaking.)

T10 has one less turn.
T11 reduced by 1 turn.

45mhz IF replace (Q20, Q21, Q22) with BFR106.? Change R23 to 18ohms.? Change R27 to 39 ohms.
!2mhz IF amp change R43 to 18 ohma and put a .1uf in series with 680 ohms across R41.

Replaced Q10 with BFR106 for better receive gain at 20mhz and up.? (I may change out the two 3409s).

Add LM7806 regulator in handy location to limit voltage to ta2822 to 6V on pin 2.
Add 1K resistor from negative side of C77 to ground (prevents pop when pluging in
headphone or speaker)

Add 16K resistor from base o ground of Q70 for better overload performance.

The one change that really helped the transmitter was going to the 2n2222A (TO18) part.
Before that it was 13W on 80 and barely 7 on 40 and less on 20.? After that change alone
40 was near 10W and 20 was about 8.5W.? This has been tried on another unit that
was weak on 40M and it really helped with no other tricks.

Enough for now.? I plan to spend a few days re-rolling the software off the V4.3 release
for my user interface which will not include CAT, CW or a rotary encoder.? Without CW
mode the sidetone CW-Tone and CW-KEY pins are usable for general IO by removing
R256 and R105.

Allison

Interesting Michael!
That seems to be a simple and effective mod!
What surprises me though is:

P.S. There are no undesirable side-effects (i.e. I don't hear audio from the mic in the headphones on SSB TX).

The schematic suggests that the mic signal?will be?fed back to the audio amp during TX, so I'd expect you'd hear your own voice through the speaker while transmitting SSB.

73 Allard PE1NWL

F1BFU, Gilles,

I don't see a PayPal from you, please check and send me a note directly at? K5BCQ"at"arrl.net

73 Kees K5BCQ??

I am lost here, what is this.
--
Allen ?Merrell

Im currently using KD8CEC skecth and my audio is about 200-1800 and im want to change it to 200-2400 range. i have no problem using the IFS to get it into range but have had no luck changing it in the sketch so that i dont need to use IFS any help to figure this out would be nice
thankyou
KE4HTB

--
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID "MotDog@..."
Mike@...

Could work.
But it's real easy to rip the pads off the board with any mechanical movement or pressure.
I use two soldering irons, one on each end.

Yes those surface mount parts are cheap.
And those those metal end pieces can separate away electrically when removing the part.
I avoid re-using them.

Jerry

I went ahead and made the mod to keep the BITX40 LM386 audio amp powered all of the time. (Currently relay K1 removes the?
supply voltage to the amp on TX).?

What I did was to remove R111 (near the LM386 audio amp) and replace it with a 100 Ohm axial, thru-hole resistor?
and soldered one end to the R111 pad closest to the LM386. The other end of the resistor goes to +12V. That is it. This
isolates the LM386 from the supply voltage switched by relay K1 and keeps it powered all of the time.?

The most significant improvement is that the "CW Sidetone Surge issue" (CW sidetone starts out low and increases in volume over a second or two)
is gone !?

With Allards CW Sidetone wiring :



the sidetone now remains at a constant level.?

I now hear noticeably less "pop"in the audio on the TX to RX transition so operating CW is much more pleasant.?

I think that this mod is a keeper.

Cheers

Michael VE3WMB?

P.S. There are no undesirable side-effects (i.e. I don't hear audio from the mic in the headphones on SSB TX).?

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Not really Robbie if your audio chain is working use it , the only change you might make is to add a 8 or 9 volt regulator in the 12vdc line to U1 as others have done.?

I use a sharp awl to break them in the center easily. ?Then remove each end. ?Those parts are extremely cheap.

That would be Kees.
His kit includes the bare PC board and necessary parts.

Hi Kees

I have send to you a money via Paypal for a order AGC and Anticlick?kit.
Have you receive it ?

73 QRO from F1BFU French Ham builder