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Hi , I have reports of distorted tx audio on my ft-767DX,is it possible to feed audio from my laptop headphone jack into the rig mic input,? then tx the laptop audio into a dummy load via the radio then monitor the transmitted audio via a diode detector using a crystal earpiece while i make adjustments?.
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Are you transmitting AM or CW [of FM]?
You can listen to AM with a simple diode detector but the levels will be critical, too low and the recovered audio will be too weak, too strong and the audio distorted.
Is there a local ham you can talk to via telephone while he monitors your audio?
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As to coupling a PC to a transceiver, yes it can be done, transformers are good for breaking ground loops but bad for picking up stray magnetic shields.
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These show several ways to do it.
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Mr. Browne knows hit stuff, both RF and AF. He was a respected audio expert for ~40 years before retirement.
I use transformers but they are obscenely expensive units with integral faraday cage, electrostatic shield between primary and secondary.?
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Jensen makes similar transformers (prepare to rob a bank). I salvaged the transformers from an audio distribution amp designed back when we (professionals) used 600 ohms for everything audio, then we went with 10K loads and the old distribution systems were tossed.
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Rod Elliot shows two circuits that can modified to drive a transceiver,
one for transmitting one for receiving
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The PC to PA can be modified for PC AF out? to transceiver AF in
The PA to PC can be modified for transceiver AF out to PC AF line in.
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If you are lucky, in a location or ham shack with no stray electromagnetic fields, Mr. Elliot's designs should work fine.
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If you decide to go with the Eliot ESP designs, this transformer can work extremely well. Several members of our shortwave listeners club use these to interface their radio to their PC for data decoding.
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One guy is a ham and uses them for both HF data and VHF data.
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G26936A + (Pkg 2) Walters OEP-1200 600 Ohm to 600 Ohm Miniature Isolation Transformer
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Walters OEP-1200 600 Ohm to 600 Ohm miniature low profile line isolation transformer is rated to comply with the relevant requirements of BS6305. Size is 0.71" sq x 0.5" tall. Has 4 pins on bottom and has an insertion loss of 1.5 dB max at 2KHz. Return loss is -20dB @ 200 Hz to 400 Hz and balance is better than 80 dB 200 Hz to 400 Hz. New. Sold in a package of 2.
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https://theelectronicgoldmine.com/products/g26936a?_pos=22&_sid=069c097ea&_ss=r
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Actual Walters specification sheet, below the Farnell blurb at the top.
https://www.farnell.com/datasheets/13721.pdf
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Note: I've purchased quite a bit of stuff from Electronic Goldmine with no problems. I have nothing to do with them other then as a customer.
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A "better" transformer might be Triad "Red Devil" transformers. I think Mouser and Newark carry them.
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On Friday 14 February 2025 09:40:38 am wn4isx via groups.io wrote: Is there a local ham you can talk to via telephone while he monitors your audio?
As to coupling a PC to a transceiver, yes it can be done, transformers are good for breaking ground loops but bad for picking up stray magnetic shields.
These show several ways to do it.
The first thing I thought of when I saw "mic input" was the possibility of overdriving it, but both of those links address this issue. Mr. Browne knows hit stuff, both RF and AF. He was a respected audio expert for ~40 years before retirement.
I use transformers but they are obscenely expensive units with integral faraday cage, electrostatic shield between primary and secondary.
Jensen makes similar transformers (prepare to rob a bank). I salvaged the transformers from an audio distribution amp designed back when we (professionals) used 600 ohms for everything audio, then we went with 10K loads and the old distribution systems were tossed.
I'm not sure I see the need for something that fancy... Rod Elliot shows two circuits that can modified to drive a transceiver,
one for transmitting one for receiving
The PC to PA can be modified for PC AF out? to transceiver AF in
The PA to PC can be modified for transceiver AF out to PC AF line in.
If you are lucky, in a location or ham shack with no stray electromagnetic fields, Mr. Elliot's designs should work fine. Funny that he mentions phone transformers. Some time back I scrapped out a bunch of modems, some PCI bus but most way older than that, most "winmodems", unusable for me as I don't run windoze. There was a transformer on each of these, and assorted other useful bits. It's interesting that he shows different dc resistance for primary and secondary, I'd have thought that they'd both be the same. Some years ago a friend of mine (who was a sound engineer) pointed some small transformers out to me in the Mouser catalog. They were fairly cheap as I recall. He said that they worked quite well if you had a resistor across each winding, otherwise they tended to ring with higher signal levels. -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin
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On Fri, Feb 14, 2025 at 01:55 PM, Roy J. Tellason, Sr. wrote:
It's interesting that he shows different dc resistance for primary and secondary, I'd have thought that they'd both be the same.
The winding are separate, one inside the other so it has shorter turns and a lower resistance, the other is outside and has longer turns so it has a higher resistance.
This isn't theory, my Bell Systems 600:600 show the same effect and are labeled as 600 ohms and XYZ DC resistance, the other is 600 ohms and ABC resistance. The side label says the XYZ winding must face the central plant. I have 4 and they are probably 80+ years old and each weigh 4 or 5 pounds.
They are packed away so the XYZ and ABC resistance.
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This data can be used as your friend, feed your output signal to the higher resistance and take your signal from the lower, this way the lower resistance is shielded to some degree by the outer winding and will >probably< pick up less stray noise.
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Forgot to mention ringing, if you are dealing with square wave, or very short bursts of AF, say 10~20 cycles of 1kHz, ringing can be a problem. I don't know why it is an issue in some transformers but not others.
I typically place a 10k metal film resistor across both primary and secondary to inhibit ringing. These values worked for me but might need to be tweaked depending on your setup.
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Ringing can be extremely difficult to see on a standard, phosphor, scope, a DSO or storage phosphor scope might be required. And you'll probably never hear it because the ringing only lasts a cycle before rapidly fading to nothing.
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This can be a real killer for modern RF data formats,
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Oh I never meant to imply that you needed a Jensen shielded transformer, in most cases you won't, but there are ham shacks with enough magnetic field strength only a premium transformer will work and they are obscenely expensive. Hence, the "rob a bank" snark.
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A quick test, connect the transformer you plan to use to a battery operated amplifier, a cassette deck will do. Use high quality mini-coax (RG-174) with good connectors and sniff for 60Hz +harmonic hum. If you have a lot, you have a problem, now I can't tell you what a lot might be because I won't have your transformer, amplifier etc. I have the coil from a 12 or 24V DC relay that I've encased in expoxy with 5 feet of RG-174. I use it for hum surveys for friends, I have an idea what is OK and what isn't but it is far from scientific.?
Now if I had 2 30V batteries, I could use my HP AF micro to 100V meter to take actual readings, but I have no idea what type relay my coil came from, it was in a friend's junk box and I didn't pay attention to anything except the dark phillips screw holding the coil in place. It was a pain to remove. I tossed the rest of the relay in his recycle bin.
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Telephone company line I-O transformers: Your comments below reminded me of setting up production and custom automated test equipment for high volume production of the transformers.? The were ferrite potcores, about an inch in diameter. They had a bi-filar wound line input side, an equipment side winding, and an extra monitoring winding. Each transformer had to be tested for 14 variables: For example, turn ratio between the windings, balances, winding resistances , frequency response, insertion loss, and a high pot test. All the test equipment ran on HP-IL with custom modules and DVMs.? We made thousands per week in Dominican Republic.? That was about 35 years ago. Bertho ?
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From: [email protected] <[email protected]> On Behalf Of wn4isx via groups.io
Sent: 14 February, 2025 16:33
To: [email protected]
Subject: Re: [electronics101] poor/distorted tx audio? On Fri, Feb 14, 2025 at 01:55 PM, Roy J. Tellason, Sr. wrote: It's interesting that he shows different dc resistance for primary and secondary, I'd have thought that they'd both be the same.
The winding are separate, one inside the other so it has shorter turns and a lower resistance, the other is outside and has longer turns so it has a higher resistance. This isn't theory, my Bell Systems 600:600 show the same effect and are labeled as 600 ohms and XYZ DC resistance, the other is 600 ohms and ABC resistance. The side label says the XYZ winding must face the central plant. I have 4 and they are probably 80+ years old and each weigh 4 or 5 pounds. They are packed away so the XYZ and ABC resistance. This data can be used as your friend, feed your output signal to the higher resistance and take your signal from the lower, this way the lower resistance is shielded to some degree by the outer winding and will >probably< pick up less stray noise.
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I love bifilar and trifilar windings but modem and very few audio transformers use that format.
I've wound special bifilar winding for a receiver for whistlers, RF 1~3kHz. Didn't work any better then a normal transformer.
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For RF they are the only way to go.
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Bettho, sir, you have lead an interesting life.
I can't imagine the difficulty of training non native English speakers to do technical work.
Hell it was difficult enough to work with native born Americans as student workers to do some of the simplest tasks. There was one kid I sort of wished would fall off a 6 story building. Yea the paperwork would have been daunting but a nightmare "worker" would have been gone.
The worst were the EE students, they thought they knew enough to not listen to directions in our TV facility.
I considered strangulation with 75 ohm coax a time or two....
They couldn't understand why NTSC black burst timing cables had to be 80M/4 long.....
[3.58 is ~80 meters] You calculate the length, apply violocity factor, cut the cable a foot long and trim back an inch at a time with a push on BNC. God I hated making those cables.
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Oddly enough the English and Philosophy majors actually listened and did as they were told.
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Those Bell systems transformers were a good size. I was designing early SMT components to be able to shrink pager size. Try winding #44 magnet wire on a 1mm, 40 mil, diameter ferrite rod and solder the wires to a ceramic substrate 0.1x0.1 inch 2.5mm. Or 5 turns bifilar wound on a 0.1” toroid with proper impedance at 450 MHz on 4 x 4mm base. The amazing part:? It was all done by hand in Haiti about 50 years ago.? It was safe in Haiti at that time.? I did not have to worry about security. Bertho ?
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From: [email protected] <[email protected]> On Behalf Of wn4isx via groups.io
Sent: 14 February, 2025 18:26
To: [email protected]
Subject: Re: [electronics101] poor/distorted tx audio? I love bifilar and trifilar windings but modem and very few audio transformers use that format. I've wound special bifilar winding for a receiver for whistlers, RF 1~3kHz. Didn't work any better then a normal transformer. For RF they are the only way to go. Bettho, sir, you have lead an interesting life. I can't imagine the difficulty of training non native English speakers to do technical work. Hell it was difficult enough to work with native born Americans as student workers to do some of the simplest tasks. There was one kid I sort of wished would fall off a 6 story building. Yea the paperwork would have been daunting but a nightmare "worker" would have been gone. The worst were the EE students, they thought they knew enough to not listen to directions in our TV facility. I considered strangulation with 75 ohm coax a time or two.... They couldn't understand why NTSC black burst timing cables had to be 80M/4 long..... [3.58 is ~80 meters] You calculate the length, apply violocity factor, cut the cable a foot long and trim back an inch at a time with a push on BNC. God I hated making those cables. Oddly enough the English and Philosophy majors actually listened and did as they were told.
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has anyone done a carrier point alignment on the 707/,its vr 3001 and tc 3004 adjustments on the af board,i am having distorted tx audio reports,is there an easy way to adjust?.
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On Friday 14 February 2025 04:32:40 pm wn4isx via groups.io wrote: On Fri, Feb 14, 2025 at 01:55 PM, Roy J. Tellason, Sr. wrote:
It's interesting that he shows different dc resistance for primary and
secondary, I'd have thought that they'd both be the same.
The winding are separate, one inside the other so it has shorter turns and a lower resistance, the other is outside and has longer turns so it has a higher resistance. Okay, that makes sense... This data can be used as your friend, feed your output signal to the higher resistance and take your signal from the lower, this way the lower resistance is shielded to some degree by the outer winding and will >probably< pick up less stray noise. I wouldn't have thought to do that, either. I'll have to check the ones I salvaged, and see what they measure. -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin
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On Friday 14 February 2025 04:43:42 pm wn4isx via groups.io wrote: I typically place a 10k metal film resistor across both primary and secondary to inhibit ringing. These values worked for me but might need to be tweaked depending on your setup. I don't recall what value my friend suggested, and it was a *long* time ago... Ringing can be extremely difficult to see on a standard, phosphor, scope, a DSO or storage phosphor scope might be required. And you'll probably never hear it because the ringing only lasts a cycle before rapidly fading to nothing. I used to see it all the time with my Tek 2246 when troubleshooting stuff like the c64. Probably because I was using the longer ground lead on my probe. It was a surprise to me that the darn thing worked at all with how dirty those signals were. This can be a real killer for modern RF data formats, I have yet to play with any of those. Hell, with no antennas up and only having one in the cars I haven't been on the air in ages. Never mind getting into all of that stuff. Oh I never meant to imply that you needed a Jensen shielded transformer, in most cases you won't, but there are ham shacks with enough magnetic field strength only a premium transformer will work and they are obscenely expensive. Hence, the "rob a bank" snark.
A quick test, connect the transformer you plan to use to a battery operated amplifier, a cassette deck will do. Use high quality mini-coax (RG-174) with good connectors and sniff for 60Hz +harmonic hum. If you have a lot, you have a problem, now I can't tell you what a lot might be because I won't have your transformer, amplifier etc. I have the coil from a 12 or 24V DC relay that I've encased in expoxy with 5 feet of RG-174. I use it for hum surveys for friends, I have an idea what is OK and what isn't but it is far from scientific. I'll keep that in mind if I ever get any reports of hum or similar on my signal, if I ever get back on the air again. -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin
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Bertho