This case is available.

Christopher

On Sun, Dec 22, 2019 at 5:42 PM Sheldon Howard <drsheldonhoward@...> wrote:

If the case is still available, I would?like to purchase it.?

On Sun, Dec 22, 2019, 3:59 PM Ken Hansen <ken@...> wrote:

Hello all,

After selling my unbuilt uBitx & Bitx40 (thanks again to all that expressed interest), I just uncovered a Carl Beck (SK) 3D-printed uBitx case & knob kit, new and unused.

This kit was made for the uBitx specifically, with all appropriate holes and openings as needed. This case is suitable for a recent version of the uBitx, NOT the V6 model with the touchscreen.

I repeat, this is NOT suitable for the current V6 uBitx.

More information can be found here:?

If interested, I’d like $45 shipped, but I’ll entertain offers.

This case is no longer available, this may be one of the last examples of his work available, ready to contain your uBitx V5 or earlier..

Thanks,

Ken, N2VIP

Just crush the transistors with a set of small diagonal wire cutters and wipe the legs off the pads with a low watt soldering pencil.? Save the $16 plus shipping on the chipquik.

?

From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Sunday, December 22, 2019 11:49 AM
To: [email protected]
Subject: Re: [BITX20] TOPIC OF THE v3 v4 L5 L7 Mod GOT ME WONDERING

?

On v5 (and v6), the changes Farhan made to reduce the 45mhz-DialFreq spur are as follows:
? ?v5 has a new low pass filter at L31,L32,C205 to block the 90mhz harmonic of the 45mhz IF
? ?R26 is now 220 ohms, to increase current (and reduce distortion on large signals)
? ?Transistors Q20,21,22 are now BFR93W for lower distortion (less harmonics) at 45mhz

I have listed those in what I consider to be their order of importance.
Changing out the transistors is the most difficult, and the other two changes may well be
sufficient to reduce the spur enough to meet FCC regs.?

I suggest using a low temperature alloy such as ChipQuik if removing those transistors:
? ??
You first wick away most of the old solder using solder braid and flux, then add a bit
of the ChipQuik as if it were normal solder.? If that ChipQuik is more than luke warm
(via either a soldering iron or a $20 hot air embossing gun) it will be molten, making
it easy to pluck the transistor off with tweezers.

ChipQuik will also be useful when removing the old relays, if replacing them with Axicom relays.
You must either replace those relays or use an external filter appropriate for each band
to prevent harmonics from going out on the air with a v3 or v4 rig.

Here's the discussion in the forum where Farhan developed those changes:?
? ? ?/g/BITX20/message/61645
Note that there are 70 messages in that thread, and there are other such threads.
That particular message doesn't mention the transistors, but the 2n3904's simply don't have
sufficient Gain-Bandwidth-Product to work well at 45mhz, and so distortion occurs?
which produces that 90mhz second harmonic.? But if the filter of L31,L32,C205 is successful
in preventing the harmonic from reaching the first mixer, that's most of the fix.

For better performance during receive, you might also want to change out Q10,11,12?
to the BFR93W's.??

How swapping out L5,L7 for shielded parts would reduce this particular spur
is a bit of a mystery to me, but could well be the case.? Shielded coils
would prevent high magnetic fields in the nearby final amp from getting back into
the IF amp, so worth doing if you have them on hand.? There were other?
problematic spurs beyond the 45mhz-DialFreq spur that this could cure.

There were a bunch of other changes around the audio amp for v5.??

If you have an LM386 or a non-DX branded TDA2822 working in the audio amp, that should be fine.
The discrete transistors of v4 worked well enough for many, but if you have trouble with distortion
or insufficient power it should be easy enough to patch in an LM386 or TDA2822.
That new 2n7000 is there in front of the audio power amp on v5 to reduce annoying PTT pops
in your received audio when keying the mike, but is not essential.

Lots of changes to the final power amp for transmitting, these bring up the transmit power?
on the higher frequencies.? Without these mods you may only get a watt or two at 30mhz,
while getting perhaps 10 watts on 3.5mhz.? But these mods are hardly worth the trouble.
I would just use an external linear such as the 10W linear from QRP-Labs if you need more power,
though you will need an appropriate attenuator between the uBitx and that amp.

Be careful of increasing mike gain beyond what's available in the design as shipped from hfsignals.
Increasing mike gain to compensate for loss of gain in the transmit power amp at higher frequencies means
larger signals in the IF amps, and thus more distortion in those amps and in the mixers,
and thus far far worse trouble with spurs which you won't be aware of unless you look it over good
with a spectrum analyzer.? The rig can sound fine on the air, and still be putting out significant
out-of-band spurs if the mike gain is too high.

Jerry, KE7ER



On Sat, Dec 21, 2019 at 08:17 PM, Jerry Gaffke wrote:

Raj found that using a particular brand of shielded inductor fix at L5 and L7 would cure that spur.
Some report it didn't work for them.
Farhan found he could tame the spur on his rig by adding a filter between the 45mhz IF
and the first mixer that prevented the 2'd harmonic of 45mhz from getting into that mixer.
Again, this is a kind of tricky fix.? ? When I search for "spur" in the forum I get 757 hits, mostly
discussions about the above two possible ways to fix this spur.
On v5 and v6, Farhan changed a number of components to reduce the harmonic content
of the signal from the 45mhz IF, this fix is working very well.

OK, so have a Bitx40, very pleased with the rig, but had to make a number?of fixes to get it working how I wanted and still have a couple to finish. This uBix V6, is this a ready to run model, or is there a number of fixes needed again?

?

Dont mind the fixing but if not fully documented, like some, it can take a long time.

?

Thanks?for any and all input Vaughn

Another fix might be to make two band-pass filters, one for 15m that has skirts near the band edges (low at least 20mhz, high just above 22), and one that has a low-end cutoff just around 15m and high just above 10.? Do it right, and you've got a good clean signal.

IMO, that would be a simple solution for running SSB on higher frequencies - maybe more reliable and easier than the mods I've read about (I don't have a uBitX so I've not done much reading on that radio).

Bob
N4FBZ

Raj found that using a particular brand of shielded inductor fix at L5 and L7 would cure that spur.
Some report it didn't work for them.
Farhan found he could tame the spur on his rig by adding a filter between the 45mhz IF
and the first mixer that prevented the 2'd harmonic of 45mhz from getting into that mixer.
Again, this is a kind of tricky fix.? ? When I search for "spur" in the forum I get 757 hits, mostly
discussions about the above two possible ways to fix this spur.
On v5 and v6, Farhan changed a number of components to reduce the harmonic content
of the signal from the 45mhz IF, this fix is working very well.

Harry,

Many folks used the v3 and v4 boards without mods (and some no doubt still do).?
They don't meet spec with regard to FCC regulations, which require all
spurs and harmonics to be 43 dB down from the main signal.
As I recall, in some cases these undesired transmissions were only 30dB down.
By 30 dB down, we mean that the undesired signal is 10**(30/10) = 1000 times weaker
than the?primary signal of 5 or 10 watts coming out of the uBitx, so perhaps 10 milliwatts.
Regulations in some jurisdictions other than the US are significantly tougher than our 43dB spec.
As far as I know, nobody has actually gotten into trouble because of these issues,
but we should all ensure that our signal is above reproach.

The v3 and v4 board layout for the relays used for switching between the four low pass filters
for transmit allowed some of the harmonics to sneak past the filters.
One fix is to replace those four relays with Axicom relays, which are more suitable for RF.
Search the forum on the groups.io website for "Axicom relays", will find many hits.
An alternative is to add an external low pass filter between the uBitx and your antenna:
? ??/g/BITX20/message/71710
On v5 and v6, Farhan found a way to route the board differently that gets good performance
from the original relays, this fix is working very well.

Once you have the transmit LPF's properly filtering out harmonics,
you are within FCC limits on all bands for CW operation, and all but 15,12, and 10 meters
for SSB operation.? For SSB operation on those high bands, you will have a spur
at 45mhz-DialFreq.? For example if transmitting on 29mhz, there is a spur at 45-29=16mhz.
On the 80,40,30,20,17 meter bands this is not an issue because the transmit low pass filter
will take it out the spur.

Raj found that using a particular brand of shielded inductor fix at L5 and L7 would cure that spur.
Some report it didn't work for them.
Farhan found he could tame the spur on his rig by adding a filter between the 45mhz IF
and the first mixer that prevented the 2'd harmonic of 45mhz from getting into that mixer.
Again, this is a kind of tricky fix.? ? When I search for "spur" in the forum I get 757 hits, mostly
discussions about the above two possible ways to fix this spur.
On v5 and v6, Farhan changed a number of components to reduce the harmonic content
of the signal from the 45mhz IF, this fix is working very well.

My recommendation:
Fix the harmonics, either by replacing the relays with Axicom relays or by using an external low pass filter board.
And don't operate SSB on bands 15,12 and 10 meters to avoid any issue with the spur.

Jerry, KE7ER


On Sat, Dec 21, 2019 at 07:07 PM, Harry Latterman wrote:

I have not have time to build the V3 kit I got in a trade, but plan to soon.? The who thing about the spurs kind of made wonder how many hundreds or even thousands of V3 and V4 radios are out their being used often and the owners are not awared of this issue or maybe some don't even care.? How bad is this problem anyway... Also I was looking at I believe the V5 board and I believe L5 and L7 are not SMT parts but cores.? I guess they seem to work better then the tiny-little parts.? If so why not use them.? This was going to be a future question, but I figure I would ask now...

73 Harry K7ZOV

On Dec 21, 2019, at 2:12 PM, Jim Sheldon <w0eb@...> wrote:

?

Mine too. ?DHL tracking shows it's due Thursday. ?Probably would have gotten here Wednesday but they won't deliver on Christmas day and I don't blame them.

Jim - W0EB

------ Original Message ------

From: "Joel Caulkins/N6ALT" <caulktel@...>

To: [email protected]

Sent: 12/21/2019 12:49:00 PM

Subject: Re: [BITX20] bitx v6 is here

I just received notification and tracking information on my V6, so it should be here in US in about a week. I will post when it arrives. Don't know why I'm getting excited about this, this will be my 8th Bitx since they were introduced.

Joel
N6ALT