I believe you make a good point regarding unattended HF beacons. If I may clarify a technical point regarding the nature of balloon flights, I understand your reference to high altitude balloons to mean the flock of balloons sent flying around the 10k meter (30k feet) altitude. In the world of free-flight balloons, high altitude balloons (HAB) are those that have a large balloon filled with enough gas to rise quickly to around 30k meters or 100k feet and then burst, allowing the payload to float back to earth, hopefully slowed by a parachute. Flights last a few hours usually, often much less. This type of flight makes good use of VHF/UHF frequencies and even low microwave i.e. Wifi frequencies. An argument could be made that flights of this nature could use HF transmitters as the working time is so short, the transmission will end within a known time, a crude form of operator control. The lower altitude long distance and long duration flights must of course use HF to be of any value and to be easily tracked. I am not sure if we have an acronym for these long distance balloons, but I think these are the ones that create the question about the propriety of using the unattended HF beacons.

It seems the 'newer' crop of ARS operators have less concern about sticking strictly to the regs than those of us who came into the hobby thru a lot of hard work and study. I was first licensed in 1972 and am of the old school, I'm afraid. I have a moderate amount of pride in what I have accomplished and feel strongly about the need to protect this hobby, one of the few that are internationally regulated. I have zero tolerance for violations, whether committed by others or myself. Inadvertent or unintentional violations are bad enough, deliberate is inexcusable.

Man! This soapbox is so high I am suffering hypoxia!
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Wes

AE6ZM

Hereford, AZ

?-.-

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On 2/01/2018 7:22 AM, Michael Lloyd wrote:

The filter starts to roll off at about 4.35MHz
3dB down is about 4.92 MHz
By 20m it's about 20dB down

Mike, the SpecAn screen shows a sweep from 3MHz to 8.555 MHz.? I assume the "10dB/" on the upper left of the screen means 10dB per vertical division?? If so, the trace appears to be already more or less 30db down at 8.555 MHz and yet you mention "By 20m it's about 20dB down" which has me a little confused.? Normally the attenuation through a LPF is expected to continue increasing with frequency, so what does the SpecAn show when the 'stop' frequency is changed to, say, 53 MHz?? (e.g. 5 MHz per horizontal division)

73, Bob? ZL1RS

Hi Mike,?

Happy 2018 to you and yours as well Mike.?

The Agilent input is 50Ω. The alligator clip was coming from the tracking generator. I have 50Ω terminators and attenuators from Mini-Circuits (gotta love those guys).
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73
NE5U

Mike

Gang

First, proceed with care. Review the specified damage input voltage for the U3S, and measure your candidate supply to insure its well below.

Second, being an RF device, avoid any dc to dc converter unless it is substantially filtered for RF use. The example referenced seems to be for pc use.

An old linear transformer based walwart could work, but most are unregulated.? also beware its output voltage can be much higher than the printed value when under a light load. We don't want to fry the U3S when its not transmitting. A 5 volt regulator and some capacitors can be added outboard, the circuit on the regulator data sheet is a starting point.

Some have bought a 5 volt linear supply by mail order, but I don't recall details. Measure the output voltage of any supply before plugging in your U3S.

Curt

Bruce - that helps a lot. 2.4W more closely matches my vector wattmeter (LP-100).?

I'm afraid I have a few different issues to deal with. I'm going to focus on T1 and work back to the other problems once that's resolved.?
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73
NE5U

Mike

:-/ Secondary #1 looks like it has 6T not 5T. That can't be good either. I'll check with the microscope and see if that is correct. I'm pretty sure it is.


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73
NE5U

Mike

I decided that I should focus on the problem that I'm having rather than poke around in places that aren't likely to be the cause. It's a cold blustery day outside and a holiday... good for poking around. Not good for solving problems, which in this case is poor alignment results.

I would have bet real money (50 cents US) that I had good BPF settings when I aligned the kit the first time but there is no way that could be right. When I (just now) tried to tune the BPF the best reading (on the display) is 2 and about 3/4 of the bars. So something is wrong with T-1, more specifically how I wound it or something to do with solder joints perhaps. I started troubleshooting with voltage checks around T-1.?Aha! I found 0V on pin 7 of T-1. I heated the connection up and now have the same voltage on Pin 7 and 8.? reasonably close to Han's voltage chart. But... the BPF alignment readings are still the same (not unexpected at all). C1 is nearly wide open so I guess I need to make some changes to T1. Bummer.

Like so:

?
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73
NE5U

Mike

No. I believe your assumptions about your measured output power are incorrect. The voltage to power converter calculator on the Pasternak website assumes you are entering an RMS voltage. The qrpkits dummy load diode detector provides a peak voltage reading, not RMS. You must multiply peak time 0.707 to get RMS. SO your RMS output voltage is not 15.4v, it is 10.9v. Therefore, your calculated output power would be more like. 2.4W. This more closely follows the power curve given in the dummy load documentation.
Hope this helps.
Bruce N1RX

Hi Chauncey,

Same issue here just powered up my qcx for the first time as well, 40m filters. No matter what i do to the three pots nothing changes. Only the volume controle seems to have slight influence on the three bars for adjusting the IQ.?

Havent found a solution or issue just yet. Have you found any solution on yours maybe ?

regards,

Leo, PA1LDB

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That's a good idea Alan. Than you.?

The SA input is 50Ω but my alligator clip?, not likely. I guess I should have used a scope probe.
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73
NE5U

Mike

Continuing right along, I'm using this:?


Dummy load with peak detector that requires a DVM with an input impedance of 11MΩ. My Fluke 87V has 10MΩ input impedance. So do my two Tektronix DMM's.?

The Fluke measures 15.4 VDC on transmit. Using the chart in the document above that's not quite 3W. But... if I plug 15.4VDC into:



I get 4.74W. That's almost 5W... good enough, but is that valid?

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73
NE5U

Mike

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Hi Mike,
I'm not au fait with SA use, but Hans has already done some example plots on his site. One of them is for? 80 Mtrs


There is? sufficient info on the on screen data to duplicate the span & level settings so you can set up an identical sweep and see how close yours looks
-20dB @ 14Mhz doesn't sound right ?
I hope that's a 50 Ohm shielded alligator clip? :-\

Alan

The first day of 2018 seemed like a good day to try to figure what I did wrong when I built my QRX. I started with the LPF. Once again I pulled C29 and connected the tracking generator to the intersection of C29, C27, and L3. I did this a month or so ago and got a peak. Someone rightfully pointed out that a peak is not good for a LPF. So I did the test again and things look somewhat better.

The filter starts to roll off at about 4.35MHz
3dB down is about 4.92 MHz
By 20m it's about 20dB down

Now is a good time for someone to teach me about passband filters :o)?

The amateur radio 80m band is 3.5MHz - 4MHz. Wouldn't it be better if the filter rolled of closer to 4MHz?

Pics of the setup. You can see the marker between 4.330000 and MHz on the left side of the screen



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73
NE5U

Mike

Air currents were ideal and glad to get it in the air.
Double edge sword as the same air currents bring terrible launch weather...threading the needle :)

I've had mine running QRSS and WSPR on 40m for a couple of weeks-ish. 1W out to a tuner. Not sure what ERP was.?
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73
NE5U

Mike

Hysplit shows a straight line to Europe, in just a day and a half.

Here is the link for data -

So far so good...looks like it has reached max altitude or struggling to cut into the faster moving air...both.
As odd as it sounds,this flight was weighted down as not to exceed 10000m since this new GPS is known to fail.
Typically,this design should have flown @ 10500m...extra solar cells were used for low solar angle.
One thing also seen is the solar voltage stopped working.Maybe a bad solder joint...but at least it gets power.
8280m seems to be the max altitude...stretching of balloons may occur over time.
Jim

It's doing good, last spot shows almost 8300-meter altitude.