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Re: uBITX - A reboot of the old BITX

 

Terry

The crystals do not have to be as closely matched as some might believe.?
Bandwidth of your filter is controlled by the C-values from crystal to ground.
A bit of mismatch in crystal frequency would only be critical if you were trying
to make a filter with less than maybe 400 Hz bandwidth, and even then it
is not all that critical.? I would take Farhan's suggestion of purchasing a bag
of same-frequency crystals and just pick several that have the same oscillation
frequency.

In the early days of BITX we used what we could get locally for the crystal
filters.? Then we manually swept the resulting filter for passband, skirt steepness,
and insertion loss.? By moving the crystals around from one position to another
it was possible to come up with very effective filters.? We also played a bit with
the C-values from crystal to ground to obtain the best skirt steepness with
minimal insertion loss.? You only need to avoid those crystals which are several
KHz off-frequency in your test oscillator.

You do not have to use exactly 12.000 MHz crystals for your BITX build.? Early
BITX transceivers used 10.0 MHz crystals because they were readily available
and inexpensive.? Later we changed to other frequencies because of WWVB
bleed-through at that frequency.? If you use some other IF frequency you can
pick it to match the crystals you have available, but that does require that you
are aware of possible birdies from unwanted mixing properties.







Even slightly off-frequency crystals are possibly usable as the LO which would
be offset about 8 to 12 db down the sideband skirt of your filter.? Position of the
LO with reference to your filter characteristic can be optimized to fit your
particular voice pitch and bandwidth.

Even with manual methods it is possible to make your own high-quality filter
that may even exceed what you can purchase commercially.? The commercial
manufacturers cannot afford the time and effort that you as an individual can
devote to fine-tuning the last bit of performance out of a home-built filter.

Arv K7HKL
_._


On Tue, Jun 20, 2017 at 2:05 PM, terryhugheskirkcudbright via Groups.Io <terryhugheskirkcudbright@...> wrote:

hi

i am interested in the ubitx and may build one from scratch but the problem is getting a set of matched crystals for the filter.

is there any supplier that can supply matched crystals.

terry


Re: 4/434

Vince Vielhaber
 

438 showed up here today - After its European Vacation compliments of DHL.

Vince.

On 06/19/2017 10:42 PM, Jack Purdum via Groups.Io wrote:
Ordered June 12, arrived today, June 19 via DHL. SN: 4 / 434. I ordered
3 at the same time; only this one so far.

Jack, W8TEE
--
Michigan VHF Corp.

offset on Raduino

OZ9AEW
 

how much offset is needed on other Bitx40 ?
when my display show 7.0320 the "real" freq is 7.0285MHz !!! I have use a Pixie with 7.030MHz X-Tal as ref.?
when it comes to Birdie on 7.199 it is on 7.210?
I am not sure about my freq.counter but if Raduino is programmed to deliver a 25MHz signal my reading is 25.0052MHz
Re: uBITX - A reboot of the old BITX

Trent Trent
 

Does anyone know when the ubitx will ne sold yet?

On 21 Jun. 2017 6:49 am, "Ashhar Farhan" <farhanbox@...> wrote:
you can buy about 50 crystals for a few dollars and sort them out.


- f?

On Wed, Jun 21, 2017 at 1:35 AM, terryhugheskirkcudbright via Groups.Io <terryhugheskirkcudbright=[email protected]> wrote:
hi

i am interested in the ubitx and may build one from scratch but the problem is getting a set of matched crystals for the filter.

is there any supplier that can supply matched crystals.

terry


Re: uBITX - A reboot of the old BITX

 

you can buy about 50 crystals for a few dollars and sort them out.


- f?

On Wed, Jun 21, 2017 at 1:35 AM, terryhugheskirkcudbright via Groups.Io <terryhugheskirkcudbright@...> wrote:

hi

i am interested in the ubitx and may build one from scratch but the problem is getting a set of matched crystals for the filter.

is there any supplier that can supply matched crystals.

terry


Re: 3D Printer Suggestions

 

I second this.? Simplify3D is fantastic.

On Jun 20, 2017 3:27 PM, "Michael Hagen" <motdog@...> wrote:

Simplify3D?? I guess.? Best $149 I spent!? You won't believe how fast it slices you model and puts in on the SD card!

They are adding every printer model they can find.

You basically get a license for 2 computers.? I think if you remove it off them you go back to 2 max.

I still have a HD somewhere I need to get it off of to bump my count back in case I need it on my laptop?


On 6/20/2017 1:10 PM, DJ2AG wrote:
Michael, do you mean Simply3D or?simplify3d?

Re: 3D Printer Suggestions

 

¿ªÔÆÌåÓý

Simplify3D?? I guess.? Best $149 I spent!? You won't believe how fast it slices you model and puts in on the SD card!

They are adding every printer model they can find.

You basically get a license for 2 computers.? I think if you remove it off them you go back to 2 max.

I still have a HD somewhere I need to get it off of to bump my count back in case I need it on my laptop?


On 6/20/2017 1:10 PM, DJ2AG wrote:

Michael, do you mean Simply3D or?simplify3d?

Re: Easy low pass filters by qrpkits

 

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First put the scope with (AC coupling Set) on the generator output, get a voltage (p-p Peak to Peak is fine). Then while monitoring that

point, put 50 Ohms across generator and scope probe.? If it goes approximately in half, you are in good shape.

The connect Gen to input of the filter, 50 Ohms and scope to output.? Try going 5 - 10 MHz and plot the output.

You might want to first watch the input voltage over that frequency range.? You hope it does not change much.

If it does you will have to subtract or add input changes to you output voltage plot.

Go for it.? It is exciting to do this stuff!? A hell of a lot better the watching the News!

Mike, WA6ISP


On 6/20/2017 12:52 PM, EA3IAV wrote:

Ok i have s dummy load of 50ohm

this would be the thing

signal generator - filter in - probe of the oscilloscope in the vcc of the filter OUT-dummy load?

??

which signal? If i input 7mhz it will let it pass i guess

Re: 3D Printer Suggestions

 

Michael, do you mean Simply3D or?simplify3d?
Re: Easy low pass filters by qrpkits

 

I use the QRP labs relay kit for homebrew radios works very nice. Below is the almost finished version I have now. 5V and do upto 5 bands or all of them if you switch them out. Listed to handle 10W max.

http://shop.qrp-labs.com/ULPF
Re: uBITX - A reboot of the old BITX

 

hi

i am interested in the ubitx and may build one from scratch but the problem is getting a set of matched crystals for the filter.

is there any supplier that can supply matched crystals.

terry
Re: 3D printed knobs

Matt Patterson
 

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I have a Monoprice Mini and a Monoprice Select Plus. ?Both are excellent printers.

Matt

Sent from my iPhone 7

On Jun 20, 2017, at 8:41 AM, R S via Groups.Io <rons8@...> wrote:

What 3D printer are you folks using and sites or are they purchased locally to you? ?What are they priced at?

Thanks
Ron. KJ4FFG?




On Tuesday, June 20, 2017, 09:25, Michael Hagen <motdog@...> wrote:

I also used supports, the big Knob is hollowed out some places. I made
2, both came out perfect.? Simply3D makes me an Expert!

Takes a exacto knife to dig out the supports.

I love that program.? If you don't have a 6-32 tap, you can heat up a
long 6-32 screw (held in vice grips) and thread the holes.

Mike, WA6ISP
Re: 3D Printer Suggestions

Matt Patterson
 

¿ªÔÆÌåÓý

I have a Monoprice Mini and a Monoprice Select Plus. ?I printed the case on the plus. ?

Matt

Sent from my iPhone 7

On Jun 20, 2017, at 10:06 AM, Doug W <dougwilner@...> wrote:

That looks like a great deal.? I bought a printrbot simple metal when they first came out.? I am still very happy with it but I tell everyone that asks you can do as good or better for less money.? Looks like this is another one that proves that.

Re: Easy low pass filters by qrpkits

EA3IAV
 

Ok i have s dummy load of 50ohm

this would be the thing

signal generator - filter in - probe of the oscilloscope in the vcc of the filter OUT-dummy load?

??

which signal? If i input 7mhz it will let it pass i guess
Re: Easy low pass filters by qrpkits

 

¿ªÔÆÌåÓý

You need to test it with 50 Ohm load (a short leaded resistor or SMD).? The generator needs a 50 Ohm output, that may be the major problem.? Use 100 MHz scope and good x10 probe.

If you have a signal generator that goes to 7MHZ.? Load it with the 50 ohm resistance.? The non-loaded value on the scope should go to 1/2.

That would be good, the generator has 50 Output Z.?

Mike, WA6ISP


On 6/20/2017 12:39 PM, EA3IAV wrote:

I do have an oscilloscope. I may inject rf signals and see if they are neutralized right?

Re: Case

 

Wow, everybody else's BITX looks so much better than mine, and I tried so hard to avoid the "homemade" look!? Haha!


--
Darren, W9ZIM
Re: Easy low pass filters by qrpkits

EA3IAV
 

I do have an oscilloscope. I may inject rf signals and see if they are neutralized right?
Re: Easy low pass filters by qrpkits

 

EA3IAV

Test or evaluation of filters when you have very limited test equipment is not an insurmountable
obstacle. Build a diode probe or RF detector to use with your DC voltmeter to measure output
of the filter.? Build a reasonably stable oscillator that covers the frequency of interest.? Input this
signal into the filter and measure and record the output as you tune across the filter passband
in 100 Hz steps.? Then write those readings on graph paper for voltage based reporting, and on
log paper for db based reporting.

Arv
_._

On Tue, Jun 20, 2017 at 1:27 PM, EA3IAV <Cesarleon@...> wrote:
Are this kits any good?
i have purchaed the 40m version to check it up. How can i test its performance? I have an oscilloscope but ?I am total noob with it. It has signal generator too
I see no big difference using it

?It is cheap ($15) and easy to build. Most conplicated thing is taking the whole thing in an alu box. I guess it may be installed inside the bitx too
Easy low pass filters by qrpkits

EA3IAV
 

Are this kits any good?
i have purchaed the 40m version to check it up. How can i test its performance? I have an oscilloscope but ?I am total noob with it. It has signal generator too
I see no big difference using it

?It is cheap ($15) and easy to build. Most conplicated thing is taking the whole thing in an alu box. I guess it may be installed inside the bitx too

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BITX QSO Night, Sunday, June 25, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

 

BITX QSO Night, Sunday, June 25, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

Join us as we make contacts from BITX40 to BITX40 on 7.277 MHz in 40 meters!

To participate, call CQ BITX at 7pm sharp, your local time, on Sunday. Call off and on for about 15 minutes. It is helpful if you call CQ BITX with your name and location.? Repeat your call a number of times if conditions are weak.

This is a worldwide event at 7pm in each time zone.? You may participate in any time zone, regardless of your location, so you may wish to call in at 6pm, 7pm and 8pm, your local time, to contact hams in adjacent time zones.

The backup frequency in case of QSB or other noise is 7210 kHz.

Report your QSO's, discuss propagation, noise, signal reports, audio reports, antenna type, etc. in this thread.

This is an undirected, scheduled event.? The BITX QSO Night relies on you to call CQ BITX to initiate contacts with other stations, so warm up that final and transmit a few calls at 7pm on Sunday.? Talk to you then!
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