On Sat, Dec 30, 2017 at 12:01 pm, Gordon Gibby wrote:

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?(A "manual" for factory alignment would be wonderful....)? ?

Useful???

So after finishing up most of my projects a few days ago… I really needed something to do… so I put on the drawing board… a 100w automatic tuner that can work with the uBITx (intended to go inside the same case actually) that provides power, SWR, band memory for same antennas, low power tune, bypass, etc. all in a kit form for about $30.? I’m prototyping the think now and will work on the tuning/communications code (to integrate into the Raduino) shortly.? I’ve contacted a few of you off-channel to work out some protocol/communication issues…? but Stay tuned (double play on words there)! ???

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Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

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Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

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Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

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From: [email protected] [mailto:[email protected]] On Behalf Of Gordon Gibby
Sent: Friday, December 29, 2017 8:21 AM
To: [email protected]
Subject: Re: [BITX20] ALE, WINLINK and uBitX

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Good pickups!

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So the ALE (automatic link establishment) crowd, much like the WINLINK crowd, tend to use LOTS of bands....and thus they find ways to make their antenna systems work on mulltiple bands.? ?Here are some of the most popular ways:

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1.? ?Fan Dipoles (time honored technique of tying multiple dipoles together at the CENTER, and the energy tends to go to the correct one, since all the others present much higher impedances.? ?The wires "fan" out with usually wooden spreaders at the? end and some string involved to keep them somewhat separate.? ?Been there done that many times, my college ham club has a 3-band unit up on the top of an 11 story building rightnow that I built for them.? ?Build for yourself, dirt cheap.?

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2.? Auto-tuners? --- everyone makes these now and many can tune as soon as they see RF, or even return to previous settings that were memorized.? ?LDG,? and others.? ?Low power versions for $100? ?End fed wire to balanced line fed dipoles---they work with lots of different kinds of wire.?

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3.? Inherently multiband antennas:? ?example, full wavelength loops.? ?Build for yourself.? ?

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4.? Carefully tuned end-fed transformer-fed antennas --- there are now several of these on the market and they give an acceptable SWR on mulltiple harmonically related bands.? ?Tend to be close to $100

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5.? (the one I dislike)? resistively terminated folded dipoles --- these use a resistor to make up for what a folded dipole can't create and give an SWR that is "acceptable" literally across EVERY FREQUENCY in a decade of frequencies.? ?3-30 MHz.? ?The tradeoff is loss, as much as 10 db at times.? And they generally are pricey.

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6.? There are some multi-band vertical antennas on the market that are basically vertical fan dipoles, but scrunched up in a nice package.? ?An elderly ham in my city has one, 32 feet tall....a gang of us put it up and doggone it does from from 40 meters all the way through 6 meters

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And there are probably many more....

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Gordon

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From: [email protected] <[email protected]> on behalf of Arvo KD9HLC via Groups.Io <arvopl@...>
Sent: Friday, December 29, 2017 9:12 AM
To: [email protected]
Subject: Re: [BITX20] ALE, WINLINK and uBitX

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An automatic tuner protects the rig during TX.? If the SWR is bad during TX, some of the signal coming out of the transmitter is reflected by the antenna back into the radio where it can cause damage.

That said, RX is optimized by a properly tuned antenna, but some good amount of signal still makes into the radio when receiving, even when the antenna is not perfect.

So I assume Doc G? is scanning for radio traffic, and then when he finds some if he wants to transmit he does something about his SWR for that frequency.

Raj,

Could you suggest a method for bypassing L1-L3? I'm not sure how I would do that with any temporary change, any approach I can think of would be permanent and then attempting to reverse the damage later.

And where is the output filter on the board?

Something is definitely off center, I set the Raduino to transmit out of band and the power tails off in a rather symmetrical pattern centered on 7000khz, with another attachment showing the output power vs frequency.

Thanks!

John


On 12/29/2017 11:20 PM, Raj vu2zap wrote:

Could be something with L1-3. Temporarily bypass the filter and try another test.
I have one board with the filter centered a bit and gives less power higher up the band
but we work only till 7.2MHz.

It could be the output filter also.

Raj

Still two orders of magnitude off.

My typo, I used a pair of .22 pF for .44pF (closes I could get).?

I have a suggestion when someone suggests a vendor.? The idea came to me when Vince found a 1/4" shaft audio pot (great find by the way).

On Fri, Dec 29, 2017 at 03:39 pm, Vince Vielhaber wrote:

Just heard back from Adafruit. This pot: for $1.50 is an audio taper and has a 6mm shaft (1/4" is 6.35mm).

I've never ordered from adafruit because for the longest time they wouldn't ship usps to me so the shipping was a killer.? I see they finally will ship usps.?? What else should I buy from them?? I'm not talking about the standards I can find anywhere but it seems like each vendor has a few things that are very difficult to source anywhere else.? An example would be the M7 nuts for the chinese encoders that Jameco seems to have the market cornered on.? Like most of us I have paid more in shipping than the part costs just to get something I need only to remember a day later I should have ordered something else or spent more time filling my cart on Tayda to hit $5 than it took to find what I was looking for in the first place.? So my suggestion is this, if you are naming a vendor try to also list a few things that are great cart fillers or hard to find anywhere else.? I realize with everyone chasing different projects this isn't always practical or useful, but it might be.

470pf? in an NPO or C0G or silver mica would be ideal.
Voltages there are quite low, less than 5v, so most any voltage rating.

> I've temporarily repaired with a pair of .22uF in parallel.

That would give you 0.44uF, which is 440000pF.?
Not good, I'd be surprised if it worked at all.



On Sat, Dec 30, 2017 at 08:07 pm, D. Daniel McGlothin KB3MUN wrote:

I need part specification for BITX40 capacitor C7. I know it is a 470 pF. Is it an NPO? what voltage rating?

I need part specification for BITX40 capacitor C7. I know it is a 470 pF. Is it an NPO? what voltage rating?

I need part specification for BITX40 capacitor C7.  I know it is a 470 pF.  Is it an NPO?  what voltage rating?

This week past, I put together my BITX40.  Observing very weak audio signal, I was following the receiver diagnostics video (  ) and found unexpected behavior when probing the band pass filter.  I also found that I have a bad audio jack linking the headphone jack and the speaker (probably a overheating problem).

Anyway, I was re-soldering the BPF inductors (L1..L3).  While there, I decided to resolder the capacitors (C1..C7) as well.  C7 came off when soldering one end (the other end "broke" off, and the chip came off on the iron).

I've temporarily repaired with a pair of .22uF in parallel.

Thanks,
Daniel KB3MUN