开云体育

The same problem can arise with a DIN socket. Poking a piece of copper wire into
each pin-socket in turn and using a hot iron quickly on a clean tag worked well.

Michael 2E0IHW

I should stay out of this and will not comment on either posters statements. However I will add this:
?? The necessary bandwidth for speech and music transmission was studied in detail by Harvey Fletcher and his associates at Bell Labs in the 1930s. Much of that research was published in Harvey's book "Speech and Hearing" which ran several editions. In it he shows charts showing the distribution of power in speech, the effect of frequency bandwidth and cut off on intelligibility and on naturalness. All this was of vital importance to the telephone service. The labs found that the bandwidth for intelligibility was narrower than the bandwidth for "natural" sounding speech. The naturalness was necessary because telephone subscribers demanded it. Somewhat later research published by the Russians found that the bandwidth and dynamic range of speech could be limited to the point where it was no longer possible to distinguish one speaker from another without destroying the intelligence.
?? Minimum bandwidth and minimum power use is often desirable but not always. The desired limits also depend on the amount of noise in the circuit. In quiet circuits wider bandwidth and wider dynamic range generally go with higher articulation but the presence of noise changes this.
?? The statistical nature of speech has been covered in many publications, I think it is worth some study.


--
Richard Knoppow
1oldlens1@...
WB6KBL

And my post was to caution *all* users that just slamming in a wide filter without giving it any thought is not a good idea. If you don't like that, just delete the message. It's your radio and your neck, you will do what you want. I'm used to technical advice being ignored. That doesn't mean I will stop giving it. Or that it is incorrect and "does not hold water". If you can find a problem with the Drake math, feel free to have at it. It's not rocket science, but it _is_ radio science. Your signal will be wide. That is a fact.


73

-Jim
NU0C

On Sat, 10 Apr 2021 11:12:26 -0700
"John McGrath" <solutions884@...> wrote:

Well Jim you can do your policing to someone else, I knows better there is zero problem with using this as a tx filter. Matter of fact I might even put a 4K in the other one for some ESSB. Your argument is old and holds no water except for transmission on 60 meters which I never operate the rig on anyhow.? So, I will certainly sleep just fine with this filter knowing its one of the best sounding TR7s on ssb. Heck I might even put a small EQ on it.

The post was meant to help folks out if they were looking for some filter options and not pay stupid prices people want for the "drake" filters on ebay or elsewhere.

?Well Jim you can do your policing to someone else, I knows better there is zero problem with using this as a tx filter. Matter of fact I might even put a 4K in the other one for some ESSB. Your argument is old and holds no water except for transmission on 60 meters which I never operate the rig on anyhow.? So, I will certainly sleep just fine with this filter knowing its one of the best sounding TR7s on ssb. Heck I might even put a small EQ on it.?

The post was meant to help folks out if they were looking for some filter options and not pay stupid prices people want for the "drake" filters on ebay or elsewhere.?

Tony,

I have bit of? history with problems of getting people to properly "tune" in an SSB signal!

From 1981 to about 2000 I operated the HF radios in a USAF C-141-A/B & C-17B? aircraft? and later (2009-2018)? the HF radios in the Boeing 737-800/900 ETOPS (overwater)? aircraft!.?

The C-141 was equipped with Collins 618T HF radios that operated from 2.000 to 29.999 MHz (USB only) and the Boeing aircraft were equipped with (among others ) the Collins HFS-900 HF radios. (also 2.000 - 29.999 MHz USB-only )?
?
They only "tuned" 1kHz steps and only worked on USB .....LSB was available but not needed because "no one" uses LSB in Aviation/Marine/Military/commercial service,? so it is not provided for selection on the control head.

[Actually the C-17B was equipped with a Collins HF (ARC-190 I think) that would "tune" in 100Hz steps and also had cockpit selectable LSB (WOOHOO!!) ]


All those years (aside from the hassle of getting people on 75 and 40 to actually talk to me on USB ......"What're you doing on the "WRONG" sideband???" )? I had one heck of a time when someone was using an older analog radio getting them to "tune" me in. (there's only one "frequency" where an SSB signal sounds "right"......I can probably tell + or minus about 20-30Hz "off"t)? I routinely had people 50-100Hz off that couldn't or wouldn't try to get closer!!?

It was sometimes a little frustrating!

73/Rick

John,

Your perception is on track. ?Considering a passive LCR equivalent circuit model of a Quartz crystal mounted in a holder with wire connection leads, the third overtone, the next highest possible resonance after the fundamental, has a lower impedance, purely resistive at resonance, and much, much lower than the nearby parallel resonance, w.r.t. frequency. ?The series resonance occurs first, then as frequency increases slightly beyond series resonance, the crystal becomes inductive with a very high impedance at parallel resonance (again purely resistive), occurring at the fundamental and each valid overtone. ?With increasing overtones, the series resonant impedance (resistance) drops somewhat linearly. ?With the voltage across the crystal being proportional to the crystal impedance, the third overtone will (normally) result in a lower voltage.

Apparently when this radio was designed, these “higher” crystal frequencies were generally only available for third overtone. ?Hence, the Colpitts oscillator, using parallel inductance, was used for greater output. ?The third overtone series resonance crystal creates a low impedance in the cathode circuit, only at third overtone resonance resonance to lower negative feedback and increase the gain. ?With the tuned tank circuit in the feedback path, the Colpitts oscillator configuration is realized. ?The 2-B manual couldn’t accurately call this a Colpitts oscillator, because of the use of the low impedance path created by the crystal in the cathode circuit, and apparently didn’t what to take the manual-space to explain it thoroughly (alright with me). ?Even though fundamental frequency crystals are available at these higher frequencies these days, you what to use what the circuit was designed for, the third overtone series resonance (using AT-cut Quartz). ?I will be interested to know the difference in price between an HC-48/U holder and an HC-49/U holder, with 10 ppm crystal frequency accuracy, depending on how WD8DAS quotes your crystal.

Let’s see what the L10 adjustment will do, after checking the circuit wiring. ?Make sure someone before you did not modify the circuit.

73,
Michael Smith, N4KZO

It’s not really pointless to adjust the 20 M coil, with L10 used exclusively for 20 M band resonance. ?There is a threshold inductance value that will cause oscillation: correct inductance is essential in this design. ?It is possible, if the coil is so far out of adjustment (or DC open-circuit in the winding), oscillation will not occur, confirmed with no grid leak bias. ?Consider noting the present position of the coil’s adjustment screw, then experimentally adjust this coil, without going beyond the mechanical stops. ?You can always return to the present coil position if an adjustment doesn’t help.

Michael:

Thanks for making me take a closer look at this.? I was able to get one of my two 18Mhz xtals to resonate by running L10 in and out until the neg voltage popped up on the meter and then tweaking to peak it.? I also peaked the 15M xtal which had been resonating but not a? very high level.? Now all three, 40M, 20M, and 15M peak at pretty close to the same value, around -260-270mv, relative to the 80M value being zeroed out, per the book instructions.

The only problem I have now is that none of the crystals fit tightly into their sockets.? The 40M is so loose you'd think it would fall out if you held the radio upside down.? You have to push the 20 and 15 xtals around until you get them to a point where they oscillate and if they get jarred, they will most often stop oscillating until I wiggle them again.? Doesn't look like it will be easy, if possible, to get at the bottom of the xtal sockets and try to squeeze them a bit.? The access is awful and they're really small.? I'm open to suggestions on this.? Off hand I can't think of an easy way to add a mm or two to the xtal pins diameter either.

de John, K8NN

I'm not sure this would be a good idea for a transmitting filter. It would allow transmit signal beyond the nominal 3 KHz SSB bandwidth from the *carrier* frequency to escape into the ether. Remember that your passband does not start at zero, but rather in the low hundreds of HZ. People think the standard SL2300 filter is restrictive but in reality it is not so much as you would think. The center frequency of the SL2300 is offset from the nominal IF carrier frequency of 5.645 MHz by 1.4 KHz. This places the low end of the passband around 250 Hz and the high end about 2.55 KHz. If the Noble 2.8 were aligned to the same spec for the low end that would place the high cutoff at 3.05 KHz so to do it right it should be at least 50 Hz lower keeping in mind that the filter skirts are not a brick wall. Too low and carrier suppression will suffer. You don't want a lot of low end response anyway because too much low steals power from the mid/highs where most intelligibility lies. This is why no manufacturers that I know of use 3 KHz transmit filters.

It seems like a 3 KHz bandwidth on transmit does violate the rules on 60 Meters: §97.303(h), "Amateur operators shall ensure that their emissions do not occupy more than 2.8 kHz centered on each of these center frequencies." Don't use it on 60M SSB!

I can't find anything specific in Part 97 regarding SSB signal bandwidth on HF, although §97.307(a) states "No amateur station transmission shall occupy more bandwidth than necessary for the information rate and emission type being transmitted, in accordance with good amateur practice." At the least you would need to take extra care near band edges as appropriate for which sideband you are operating.

Be careful with this one. :)

73

-Jim
NU0C

On Sat, 10 Apr 2021 07:05:12 -0700
"John McGrath" <solutions884@...> wrote:

Just wanted to send out a kudo's to Frank at Noble Radio. I ordered a custom made 3K filter for the number one slot on my TR7. It arrived quick with full set of instructions that were easy to comprehend. The filter was just what I was looking for. I would not hesitate to order again from him.

Hey,

You still getting those big fish at Costco?

开云体育

Just wanted to send out a kudo's to Frank at Noble Radio. I ordered a custom made 3K filter for the number one slot on my TR7. It arrived quick with full set of instructions that were easy to comprehend. The filter was just what I was looking for. I would not hesitate to order again from him.?

开云体育

Fully agree, Neutrik is really good stuff. Worth every Cent.

You may also try Hirschmann/Belden connectors. I had good experience with them, too.

Sometimes you can tell just from the price. If it's too cheap, don't be surprised if it's not worth more than you paid. If it comes to coaxial (and other) connectors, I make no more compromises. Did that when I was as student and had little money. Often ended up with melted connectors...

Someone said that proper heat is important. I second that. Too low temperatures of your solding iron are usually worse than too high. You just have to keep the time short.

Good luck with your next DIN connector!

73, Dieter DL5RDO

I hear ya, Mike!

From Central NC and not Westford...


Steve Wedge, W1ES/4

Time flies like an arrow.? Fruit flies like a banana.

Sent with ProtonMail Secure Email.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

Mike:

Thanks for that.? They're not fully up and running on the site but I did e-mail requesting a quote on the 18Mz 3rd overtone xtal.

de John K8NN