First off, you need to have a good calibrated signal generator… calibrated in db (or mv so that you can convert to db) that is either variable output or you have a good/accurate variable attenuator.? I have both and I test them against each other because there is a very slight variation of about 0.5 db between them.

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I have an old Agilent N5182 and it will output a signal down to -110 db (and I can use a variable attenuator that).? ! connect the signal generator via the attenuator to the radio RF input.? Turn the radio on, set the radio and signal generator to a frequency (lets say 10.0000000 MHZ for kicks)… the signal generator acts like a dummy load (has adjustable impedance to match output power setting).? I start at about -150 db on CW, turn the radio volume way up in SSB (important… specified filter), and then start lowering the attenuation until I FIRST notice a signal.? Now you can also so this with an RMS volt meter on the speaker leads but I find I don’t need to do that.? Find the point where I initially hear the signal generator and subtract 1 db.? that is the sensitivity; and the input in mv for (S+N)/N that gives 10 db.

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It's a bit black magic but as long as you are consistent (and have a reference that someone else did to calibrate your readings to) its OK.? I have several radios on Sherwoods list to use as references.

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Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

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Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

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Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

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Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

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email:? bill@...

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Yeah, that’s what mine looks like too. ??Glad you found the issue.? ?I’ve sold over 1,000 of those PA semi-kits now and I’ve only had three people have issues since I started selling them.? One was a power lead reversal (YIKES)… Its pretty simple… not much to go wrong.

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One thing on my to-do list is to put together a list of test points with voltages and wave forms for all of the T41 boards… and my/ mine and Olivers boards and kits.? So many things to do and never enough time!

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Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

?

Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

?

email:? bill@...

?

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I’m back for a while and working on kits again.? I put a very high priority on the new Display Driver board that fixes the T41 display freeze issue and allows a nice long cable to the display.? I offer a 3.3V ONLY kit and a 3.3V and 5V kit (until I run out of 3.3V kits… then I will only stock the combo 3.3V and 5V kit).? ??I’m still writing the assembly manual for the display kits but it should be done by this afternoon.? I will order the last few parts for them today… I should have them by Tuesday and will begin shipping them then.? Also new to the list is the 20W Dummy Load/ 40 db attenuator tap for the calibration steps.? I’ve attached the full list so you can look it over if you need something.?? Those boards and Kits with $0.00 are not in stock.? Remember, don’t send me money, I’ll invoice you… and make SURE you include your address.? All prices below are without shipping, taxes, and Paypal fee.?

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I will be at FDIM Thursday night… and have a booth at Hamvention (Booth 4111 in Building 4) where we will have a special guest… Al Peter to show off the T41 and answer any questions.? I will be selling boards and kits both places and you won’t have to pay shipping on them if you carry them away.

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Respond via my private email bill@... as to not clog the space here with our transactions.

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Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

?

Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

?

email:? bill@...

?

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Well there is no real absolute way its done as you probably know, you first need to determine the noise floor (for the mode) and that is usually the point at which the (S+N)/N = 3db (and of course, its bandwidth sensitive and frequency dependent).? If all you are interested in is the absolute noise floor at a frequency you can do this with a dummy load. ??Then the radio sensitivity is the point 10 db = (S+N)/N.? This is the point at which the signal is 10 db stronger than the receiver noise (Definition for voice comms and there are a couple of ways to do this… but most commonly with a signal generator, a good adjustable attenuator).? If you do this in CW with a narrow filter it’s taken to be 3 db.? [I could write a book here but wont]

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For the two V11 and V12 radio display impact, the difference between the display handling stuff is to determine the noise floors for each… difference them. ?Its not completely fair but it is representative.

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Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

?

Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

?

email:? bill@...

?

?

?“The latest (V12) PCBs are available for less than $5 each on the web site (/g/SoftwareControlledHamRadio). If you wish, pre-fabricated PCBs with all SMD devices already on the board are available as a semi-kit from 4SQRP (see http://www.4sqrp.com/index.php for details).”

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Yikes this is outdated…

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Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

?

Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

?

email:? bill@...

?

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Ah… old fashion Automatic Volume Control (AVC) dated from the old tube radios…to control the volume of the radio as to not blow out your ear drums… ?as opposed to RF Gain (or Automatic Gain Control) that prevents over-driving the snot out of the radio RF circuits (like the front end!) causing flat-topping, distortion, etc.? Someone was using that audio library to do that too (can’t remember who… slept since)… but it works extremely well as the video shows.

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The uBITx people are using term AGC for AVC.

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Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

?

Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

?

email:? bill@...

?

?

Yeah another mistake is pulling the wire so tight that is scrapes the enamel off the wire between turns and shorts them together.? I am guilty of doing that…

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Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

?

Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

?

email:? bill@...

?

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