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Re: USB Interface for FT8?
Steve- tnx for the suggestion about digrig.? It does seem to be more flexible and I I like the idea of built in CAT.??
Question:? Are you using it with the USB Isolator?
|
Re: USB Interface for FT8?
Digirig is worth a look, very happy with mine on my 817 and 857.
?
And you get CAT control which the Signalink doesn¡¯t do.
?
73 Steve VK2ARS
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From: lbakely
Sent: Tuesday, February 21, 2023 12:22 PM
Subject: [ft817] USB Interface for FT8?
?
I'm
planning to venture into FT8 for the first time, and I'm going to use my
FT-817.? I'm looking for a USB interface (w/ sound card), and it looks like
the SignaLink SLUSB6PM might be the most popular solution.? Is that the
right model # for the '817?? The SignaLink has been around a long time...
maybe too long (I'm wondering if there's something newer and better that's in
the same price range)??
If you're operating FT8 (or other digital
modes) on your FT-817, which interface are you using?
Any
suggestions/comments much appreciated.? Thanks much!
Larry, WA2VKG
|
Re: USB Interface for FT8?
I built mine. It's not a difficult job if you have passion as a maker.
Pietro I2OIM
Il giorno mar 21 feb 2023 alle ore 02:22 lbakely < lbakely@...> ha scritto: I'm planning to venture into FT8 for the first time, and I'm going to use my FT-817.? I'm looking for a USB interface (w/ sound card), and it looks like the SignaLink SLUSB6PM might be the most popular solution.? Is that the right model # for the '817?? The SignaLink has been around a long time... maybe too long (I'm wondering if there's something newer and better that's in the same price range)??
If you're operating FT8 (or other digital modes) on your FT-817, which interface are you using?
Any suggestions/comments much appreciated.? Thanks much!
Larry, WA2VKG
|
Re: USB Interface for FT8?
Larry,
I also use the SignalLink USB version with my FT-817. I was able to get it with the lead and configuration header.
I use it with both an Acer Chromebook with fldigi running in its linux mode and with a Rasperry Pi with both fldigi and JS8Call.
Philip Williams G4KIL
On Tuesday, 21 February 2023 at 01:22:43 GMT, lbakely <lbakely@...> wrote:
I'm planning to venture into FT8 for the first time, and I'm going to use my FT-817.? I'm looking for a USB interface (w/ sound card), and it looks like the SignaLink SLUSB6PM might be the most popular solution.? Is that the right model # for the '817?? The SignaLink has been around a long time... maybe too long (I'm wondering if there's something newer and better that's in the same price range)??
If you're operating FT8 (or other digital modes) on your FT-817, which interface are you using?
Any suggestions/comments much appreciated.? Thanks much!
Larry, WA2VKG
|
Re: USB Interface for FT8?
I have been using Signalink USB with my 817nd for a few years now on ft8 ft4 and psk31. It works fine
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On 21 Feb 2023, at 02:33, Ron Wright via groups.io <lt_wright_flg@...> wrote:
? The SignaLink is excellent interface and can get a USB version.? Also I am sure you can get the custom cable for the FT817, I did once for the fT857.? It plugged into the rear DATA port on the fT817.
73, ron, n9ee/r Ron Wright, N9EE/R Hernando Co ARES EC
Spring Hill, Florida also n9ee55@...
On Monday, February 20, 2023 at 09:05:25 PM EST, Daniel Holmes <danielh@...> wrote:
I use the signalink. It¡¯s older, but solid. Well supported, good isolation, etc. It¡¯s not the cheapest solution, but I also didn¡¯t have to spend time setting everything up, it ¡°just worked¡±, and has worked with any computer I¡¯ve hooked it to: my Mac, several raspberry pis, windows laptops, etc.
Dan --. Please pardon any mispelings or errors.
On Feb 20, 2023, at 6:22 PM, lbakely <lbakely@...> wrote:
?I'm planning to venture into FT8 for the first time, and I'm going to use my FT-817.? I'm looking for a USB interface (w/ sound card), and it looks like the SignaLink SLUSB6PM might be the most popular solution.? Is that the right model # for the '817?? The SignaLink has been around a long time... maybe too long (I'm wondering if there's something newer and better that's in the same price range)??
If you're operating FT8 (or other digital modes) on your FT-817, which interface are you using?
Any suggestions/comments much appreciated.? Thanks much!
Larry, WA2VKG
|
Re: FS Yaesu ft-817nd. Located in Toledo, Ohio. Soon Moving to assisted living location. No Radios allowd. Asking $475 plus shipping.
Hi all. ECHOLINK is also a very good option with which you can access repeaters all over the world and have QSO's. Works from a pc, tablet, mobile phone, etc.
Good luck in your future QTH.
Richard 9H1RF
On Tue, 21 Feb 2023, 02:03 Thomas Newbery via , <newberythomasusafret= [email protected]> wrote: You know, I dread that day of moving to "assisted" living, too. Perhaps you're allowed a computer and can check into "Hamsphere" or "CWHotline" to stay active in the hobby. I'm sure a local ham would assemble the CWHotline for you if money is tight. I would. KA7MWQ.
On Mon, Feb 20, 2023 at 17:00, Rich Gill Unit Sold. Awaiting payment. Tnx for looking. Rich
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Re: USB Interface for FT8?
Hello, I use with FT 818 SCU17, it is with sound card and CAT. It works absolutely perfectly in my opinion. Zdenek ok1mae 73!
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---------- P?vodn¨ª zpr¨¢va ----------
Od: lbakely <lbakely@...>
Datum: 21.02.2023 02:22:47
P?edm¨§t: [ft817] USB Interface for FT8?
I'm planning to venture into FT8 for the first time, and I'm going to use my FT-817.? I'm looking for a USB interface (w/ sound card), and it looks like the SignaLink SLUSB6PM might be the most popular solution.? Is that the right model # for the '817?? The SignaLink has been around a long time... maybe too long (I'm wondering if there's something newer and better that's in the same price range)??
If you're operating FT8 (or other digital modes) on your FT-817, which interface are you using?
Any suggestions/comments much appreciated.? Thanks much!
Larry, WA2VKG
|
Re: USB Interface for FT8?
Hi Larry,
I highly recommend that you check out the DigiRig interface.
Gigiparts sells it in radio specific bundles.
It far exceeds the capabilities of the Signalink and has none of the
Signalink potential issues.
Be it low symbol rate FT-8 or high symbol rate MIL-STD waveforms the
Digirig a clean low noise audio spectrum. As well as CAT control and
hardware PTT.in addition to CAT PTT.
Plug 'n Play radio cable sets are available for most popular
rigs.
/s/ Steve
At 08:22 PM 2/20/2023, you wrote:
toggle quoted message
Show quoted text
I'm planning to venture into FT8
for the first time, and I'm going to use my FT-817.? I'm looking for
a USB interface (w/ sound card), and it looks like the SignaLink SLUSB6PM
might be the most popular solution.? Is that the right model # for
the '817?? The SignaLink has been around a long time... maybe too
long (I'm wondering if there's something newer and better that's in the
same price range)??
If you're operating FT8 (or other digital modes) on your FT-817, which
interface are you using?
Any suggestions/comments much appreciated.? Thanks much!
Larry, WA2VKG
|
Re: results of new US antenna design - advice sought
Samuda,
This is getting silly, and your responses feel 'personal'.
I asked if this design you say was widely discussed in the 70s, 80s, and 90s was ever discussed in an ARRL publication - for some reason you took that as a challenge, it wasn't, it was a serious question. I'd find it hard to believe that any antenna that enjoyed three decades of popularity/discussion/experimentation was NEVER discussed in any contemporary ARRL publication.
The MFJ antenna I linked to was an example of an 80 HORIZONTAL DIPOLE WITH CAPACITANCE HATS, which you said would be "interesting to see", implying you had never seen such an antenna before.
Fine, you win, this antenna design from 50 years ago it totally new, was never researched or documented by anyone in any ARRL publication, and once you learn a bit more about antennas and you can show us how amazing a design it is, your name will certainly be famous in antenna circles, right up there with Yagi Uda...?
I don't know why you think I don't understand this design if your, based on a 50 year-old design is HORIZONTAL - I get it, it's horizontal.
N.B. You NEVER used the word horizontal in your initial post, the one I responded to, so I GUESSED it was horizontal and prefaced my guess with the word "apparently". Again, a question you seemed to take as a challenge.
Well, good luck with your project, hopefully someone can get you better measuring equipment than your MFJ equipment (and your briefly borrowed 'carrier class' spectrum analyzer), and maybe you'll listen to someone long enough to learn how to measure antenna performance and efficiency in a more meaningful way than logging SWR at certain frequencies.
It is kind of odd that you can't share any pictures or drawings, are you afraid someone will 'steal' your enhancement ideas to a 50 year-old antenna design?
Good luck with your 'project',? Ken, N2VIP
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On Feb 20, 2023, at 21:26, Samudra <samudra.haque@...> wrote:
? Ken N2VIP, I won't obviously change your mind -? and you have already said NEDA antenna design must have been published before in the US (still waiting) - just need to point out you can't compare the two.?
My target? design : 1ft x 1ft x 12ft horizontal. No tuning stubs, capacitive hats, or anything. Fixed assembly modules, About 10-15 lbs mass. One handed assembly.
MFJ-1785: (80m) 36" inch spokes. and different spokes for different other bands and 34 (thirty four) feet length horizontal. The mass is not mentioned, but will be higher. and?Tuning required.?
The far radiation was measured briefly with my carrier class spectrum?analyzer briefly and a signal source,? so I am confident about its radiation efficiency. Next week after erecting it permanently we will setup a station to test it over some time.? On Mon, Feb 20, 2023 at 9:59 PM Ken N2VIP < ken@...> wrote: <snip>
So for an 80m band operation, reducing that to 12feet in total length should put this antenna in a different class than what you described.?
Now if someone can point out? a horizontal dipole with capacity hats design, that would be interesting?to see. But note I defined the length?of the dipole as HWL, so on each side, we have a huge number of feet of antenna wire length.?
You mean like this?
|
Ken, N2VIP
Re: results of new US antenna design - advice sought
Ken N2VIP, I won't obviously change your mind -? and you have already said NEDA antenna design must have been published before in the US (still waiting) - just need to point out you can't compare the two.?
My target? design : 1ft x 1ft x 12ft horizontal. No tuning stubs, capacitive hats, or anything. Fixed assembly modules, About 10-15 lbs mass. One handed assembly.
MFJ-1785: (80m) 36" inch spokes. and different spokes for different other bands and 34 (thirty four) feet length horizontal. The mass is not mentioned, but will be higher. and?Tuning required.?
The far radiation was measured briefly with my carrier class spectrum?analyzer briefly and a signal source,? so I am confident about its radiation efficiency. Next week after erecting it permanently we will setup a station to test it over some time.?
On Mon, Feb 20, 2023 at 9:59 PM Ken N2VIP < ken@...> wrote: <snip>
So for an 80m band operation, reducing that to 12feet in total length should put this antenna in a different class than what you described.?
Now if someone can point out? a horizontal dipole with capacity hats design, that would be interesting?to see. But note I defined the length?of the dipole as HWL, so on each side, we have a huge number of feet of antenna wire length.?
You mean like this?
|
Ken, N2VIP
Re: USB Interface for FT8?
The Signalink is the easiest solution. I have been using one with my original FT-817. There are other interfaces with more bandwidth but the 817 is limited to about 2.8kHz. You will also want a CAT cable. The RT Systems programming cables are excellent for CAT control. The RT Systems software is really good for programming?
Bob AF9W
Happy 817 owner since 2001.?
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Re: results of new US antenna design - advice sought
On Feb 20, 2023, at 19:27, Samudra <samudra.haque@...> wrote:
<snip>
So for an 80m band operation, reducing that to 12feet in total length should put this antenna in a different class than what you described.?
Now if someone can point out? a horizontal dipole with capacity hats design, that would be interesting?to see. But note I defined the length?of the dipole as HWL, so on each side, we have a huge number of feet of antenna wire length.?
You mean like this?
|
Ken, N2VIP
Re: USB Interface for FT8?
The SignaLink has lots of features for aiding in adapting it to various rigs.?
Inside is a 16 pin socket for configuring the interface cable to the radio for the signals, one puts jumpers into it? to route the signals (PTT, tx audio, rx audio, etc) to the rear connector going to the rig.? As Don said one can also get a premade jumper PC board that has the jumpers in the board so all one has to do is plug it in.? They are made for specific radios.?
So if getting a SignaLink look for the cable for your FT817 and the jumper board.
73, ron, n9ee/r Ron Wright, N9EE/R Hernando Co ARES EC
Spring Hill, Florida also n9ee55@...
On Monday, February 20, 2023 at 09:37:31 PM EST, Don Eklund <n1edf@...> wrote:
I agree with Dan. ? ?I use a signaling with my Icom 756,7000,706,705,Yaesu ft817, 891 and my KX3. ? ?It just works. ? ? I use the remade jumpers for easy swap to other radios. ? ~ On Feb 20, 2023, at 9:05 PM, Daniel Holmes <danielh@...> wrote:
?
I use the signalink. It¡¯s older, but solid. Well supported, good isolation, etc. It¡¯s not the cheapest solution, but I also didn¡¯t have to spend time setting everything up, it ¡°just worked¡±, and has worked with any computer I¡¯ve hooked it to: my Mac, several raspberry pis, windows laptops, etc.
Dan --. Please pardon any mispelings or errors.
On Feb 20, 2023, at 6:22 PM, lbakely <lbakely@...> wrote:
?I'm planning to venture into FT8 for the first time, and I'm going to use my FT-817.? I'm looking for a USB interface (w/ sound card), and it looks like the SignaLink SLUSB6PM might be the most popular solution.? Is that the right model # for the '817?? The SignaLink has been around a long time... maybe too long (I'm wondering if there's something newer and better that's in the same price range)??
If you're operating FT8 (or other digital modes) on your FT-817, which interface are you using?
Any suggestions/comments much appreciated.? Thanks much!
Larry, WA2VKG
|
Re: USB Interface for FT8?
I agree with Dan. ? ?I use a signaling with my Icom 756,7000,706,705,Yaesu ft817, 891 and my KX3. ? ?It just works. ? ? I use the remade jumpers for easy swap to other radios. ? ~
toggle quoted message
Show quoted text
On Feb 20, 2023, at 9:05 PM, Daniel Holmes <danielh@...> wrote:
? I use the signalink. It¡¯s older, but solid. Well supported, good isolation, etc. It¡¯s not the cheapest solution, but I also didn¡¯t have to spend time setting everything up, it ¡°just worked¡±, and has worked with any computer I¡¯ve hooked it to: my Mac, several raspberry pis, windows laptops, etc.
Dan --. Please pardon any mispelings or errors.
On Feb 20, 2023, at 6:22 PM, lbakely <lbakely@...> wrote:
?I'm planning to venture into FT8 for the first time, and I'm going to use my FT-817.? I'm looking for a USB interface (w/ sound card), and it looks like the SignaLink SLUSB6PM might be the most popular solution.? Is that the right model # for the '817?? The SignaLink has been around a long time... maybe too long (I'm wondering if there's something newer and better that's in the same price range)??
If you're operating FT8 (or other digital modes) on your FT-817, which interface are you using?
Any suggestions/comments much appreciated.? Thanks much!
Larry, WA2VKG
|
Re: results of new US antenna design - advice sought
Al,
You might read on how an antenna tuner works. Tuners do more than just make the radio happy. It will result in getting more power into the antenna/radiator.? Now what the radiator does with that power is another issue.? An 18ft vert on 80m does not work very well no matter what you do.
73, ron, n9ee/r Ron Wright, N9EE/R Hernando Co ARES EC
Spring Hill, Florida also n9ee55@...
On Monday, February 20, 2023 at 08:27:26 PM EST, Samudra <samudra.haque@...> wrote:
Hmm, Al WB9UBJ,? I would point out that the NEDA antenna that I designed from the reference material I was able to gather (mentioned by others in this thread) is half-wave length in total and horizontal in configuration. There is nothing in the system that is not part of the radiator. The "end" regions are non-inductive, akin to wound (not coiled -? 2D planar windings) resistors.?
If by "Capacitive Hat" you mean a horizontal plane of conductors atop a vertical pole, where the vertical pole is the radiator, this system is not it. There is no vertical section.?The NIR Non-inductive Region (NIR) radiates low to extremely?low fraction of output power as measured by a meter. The Radiating Region (RR) is the principal radiating element. I do hesitate to publish the gain figures of the RF from calculations, but towards the center the power delivered is quite a lot, again seen?through the use of a field strength meter. The gain reduces off obviously?at higher frequencies?away from the designed band.?
So for an 80m band operation, reducing that to 12feet in total length should put this antenna in a different class than what you described.?
Now if someone can point out? a horizontal dipole with capacity hats design, that would be interesting?to see. But note I defined the length?of the dipole as HWL, so on each side, we have a huge number of feet of antenna wire length.?
The H and V polarization plots show promise, and need validation. Again, no capacitor hats of any kind, so we can cleanly fold this antenna, and then set it up in 5 mins as we have a kit built for it, as plug and play as we could make it. And the reverse is true - no tuning was required for our first trials. The nulls are as expected in the axis of the dipole much like an apple with dimples at leaf stem and blossom end.?
Guys,
It seems that you have missed exactly what this antenna is.? The cage acts like a capacity hat, adding enough impedance at the ends to bring the antenna to resonance.? I think you may also be mixing terms when talking about efficiency.? It in the above example of tuning the input to a transmission line so that maximum power is delivered into the transmission line does not mean that power is actually radiated.? Lossy parts of the antenna system, ground included, do not radiate.? There are literally thousands of articles on using capacity hats at the ends of radiators to bring the antenna into resonance but the part of the radiation resistance equation that radiates is still very small compared to a full size radiator.? So while you may approach 98% efficiency for the transmitter load, you may not be radiating that power into space.? It is possible for that power to be dissipated in wire losses, or ground losses or even in directivity sending the power to somewhere is it not useful.? When you think about shortened antennas, consider that the field generated by a short wire is going to be considerably smaller than a full size wire.? In the case of the described antenna above, I have no doubt that the antenna will present a matched load at the transmitter and it likely radiates some signal.? However, look at the wire in the cylinder and realize that the resistance of the wire in the cylinder is not radiating but it is dissipating power just like any other resistance.? I suggest that that the cylinder radiates very little as the radiation of the wires folded end to end likely cancel each other out. That does not make it a bad antenna!
There are several antenna design in the Antenna handbook that play with black magic to get the antenna to radiate on the low bands, 160 and 80.? Some actually will use large diameter coax for the radiator or will use pipe to play with the L/D ratio or one really unique design uses a combination of lengths of coax to resonate the antenna in two closely spaced frequencies to broaden the antenna bandwidth.
I would like to point out that the handbook also has some great drawings on the current distribution in antennas.? Take note of the vertical that has a large inductor at the base or center and see the disturbance in the antenna current.? Visualize the current generating a field and you can see that these antennas may still deliver full power at the input of the transmission line, but all of that does not translate into current in the radiator.
As to the use of baluns and their mention in the handbook, of course baluns are mentioned for use with dipoles.? The dipole fed at the center or even off center are balanced loads.? If the antenna is fed with coax, then an imbalance is produced.? That translates to feed line radiation which may (most often does) affect the radiation of the antenna due to fields cancellation.? If one uses a balun to couple the balanced load with the unbalanced transmission line, balance is restored and radiation of the feed line is minimized.
As to comparing with antenna performance with dipoles or an isotropic radiator, that method is valid.? We know what an isotropic radiator field will look like and what load it presents.? To compare the antenna above with a full size half wave dipole at the same location and height would be useful for someone considering the design to match criteria at their QTH.? All of us have used various antennas for years.? We all have had contacts confirmed from DX stations, many with QRP, but that does not mean the antenna is better than others.? It means you can use that antenna to transmit to someone in that location sometimes.? Remember the old adage, "you can get a wet noodle to radiate, it does not mean you should or would use that all the time".
--
Al Skierkiewicz
WB9UVJ
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Re: USB Interface for FT8?
The SignaLink is excellent interface and can get a USB version.? Also I am sure you can get the custom cable for the FT817, I did once for the fT857.? It plugged into the rear DATA port on the fT817.
73, ron, n9ee/r Ron Wright, N9EE/R Hernando Co ARES EC
Spring Hill, Florida also n9ee55@...
On Monday, February 20, 2023 at 09:05:25 PM EST, Daniel Holmes <danielh@...> wrote:
I use the signalink. It¡¯s older, but solid. Well supported, good isolation, etc. It¡¯s not the cheapest solution, but I also didn¡¯t have to spend time setting everything up, it ¡°just worked¡±, and has worked with any computer I¡¯ve hooked it to: my Mac, several raspberry pis, windows laptops, etc.
Dan --. Please pardon any mispelings or errors.
On Feb 20, 2023, at 6:22 PM, lbakely <lbakely@...> wrote:
?I'm planning to venture into FT8 for the first time, and I'm going to use my FT-817.? I'm looking for a USB interface (w/ sound card), and it looks like the SignaLink SLUSB6PM might be the most popular solution.? Is that the right model # for the '817?? The SignaLink has been around a long time... maybe too long (I'm wondering if there's something newer and better that's in the same price range)??
If you're operating FT8 (or other digital modes) on your FT-817, which interface are you using?
Any suggestions/comments much appreciated.? Thanks much!
Larry, WA2VKG
|
Re: USB Interface for FT8?
I use the signalink. It¡¯s older, but solid. Well supported, good isolation, etc. It¡¯s not the cheapest solution, but I also didn¡¯t have to spend time setting everything up, it ¡°just worked¡±, and has worked with any computer I¡¯ve hooked it to: my Mac, several raspberry pis, windows laptops, etc.
Dan --. Please pardon any mispelings or errors.
toggle quoted message
Show quoted text
On Feb 20, 2023, at 6:22 PM, lbakely <lbakely@...> wrote:
?I'm planning to venture into FT8 for the first time, and I'm going to use my FT-817.? I'm looking for a USB interface (w/ sound card), and it looks like the SignaLink SLUSB6PM might be the most popular solution.? Is that the right model # for the '817?? The SignaLink has been around a long time... maybe too long (I'm wondering if there's something newer and better that's in the same price range)??
If you're operating FT8 (or other digital modes) on your FT-817, which interface are you using?
Any suggestions/comments much appreciated.? Thanks much!
Larry, WA2VKG
|
Re: USB Interface for FT8?
The?
SignaLink SLUSB6PM? connects to the 6 pin mini-din on the back of the FT-817ND and should?work fine.?
There are other more recent sound interface devices, but they are newer with less service experience.
On Mon, Feb 20, 2023 at 8:22 PM lbakely < lbakely@...> wrote: I'm planning to venture into FT8 for the first time, and I'm going to use my FT-817.? I'm looking for a USB interface (w/ sound card), and it looks like the SignaLink SLUSB6PM might be the most popular solution.? Is that the right model # for the '817?? The SignaLink has been around a long time... maybe too long (I'm wondering if there's something newer and better that's in the same price range)??
If you're operating FT8 (or other digital modes) on your FT-817, which interface are you using?
Any suggestions/comments much appreciated.? Thanks much!
Larry, WA2VKG
|
Re: results of new US antenna design - advice sought
Hmm, Al WB9UBJ,? I would point out that the NEDA antenna that I designed from the reference material I was able to gather (mentioned by others in this thread) is half-wave length in total and horizontal in configuration. There is nothing in the system that is not part of the radiator. The "end" regions are non-inductive, akin to wound (not coiled -? 2D planar windings) resistors.?
If by "Capacitive Hat" you mean a horizontal plane of conductors atop a vertical pole, where the vertical pole is the radiator, this system is not it. There is no vertical section.?The NIR Non-inductive Region (NIR) radiates low to extremely?low fraction of output power as measured by a meter. The Radiating Region (RR) is the principal radiating element. I do hesitate to publish the gain figures of the RF from calculations, but towards the center the power delivered is quite a lot, again seen?through the use of a field strength meter. The gain reduces off obviously?at higher frequencies?away from the designed band.?
So for an 80m band operation, reducing that to 12feet in total length should put this antenna in a different class than what you described.?
Now if someone can point out? a horizontal dipole with capacity hats design, that would be interesting?to see. But note I defined the length?of the dipole as HWL, so on each side, we have a huge number of feet of antenna wire length.?
The H and V polarization plots show promise, and need validation. Again, no capacitor hats of any kind, so we can cleanly fold this antenna, and then set it up in 5 mins as we have a kit built for it, as plug and play as we could make it. And the reverse is true - no tuning was required for our first trials. The nulls are as expected in the axis of the dipole much like an apple with dimples at leaf stem and blossom end.?
Guys,
It seems that you have missed exactly what this antenna is.? The cage acts like a capacity hat, adding enough impedance at the ends to bring the antenna to resonance.? I think you may also be mixing terms when talking about efficiency.? It in the above example of tuning the input to a transmission line so that maximum power is delivered into the transmission line does not mean that power is actually radiated.? Lossy parts of the antenna system, ground included, do not radiate.? There are literally thousands of articles on using capacity hats at the ends of radiators to bring the antenna into resonance but the part of the radiation resistance equation that radiates is still very small compared to a full size radiator.? So while you may approach 98% efficiency for the transmitter load, you may not be radiating that power into space.? It is possible for that power to be dissipated in wire losses, or ground losses or even in directivity sending the power to somewhere is it not useful.? When you think about shortened antennas, consider that the field generated by a short wire is going to be considerably smaller than a full size wire.? In the case of the described antenna above, I have no doubt that the antenna will present a matched load at the transmitter and it likely radiates some signal.? However, look at the wire in the cylinder and realize that the resistance of the wire in the cylinder is not radiating but it is dissipating power just like any other resistance.? I suggest that that the cylinder radiates very little as the radiation of the wires folded end to end likely cancel each other out. That does not make it a bad antenna!
There are several antenna design in the Antenna handbook that play with black magic to get the antenna to radiate on the low bands, 160 and 80.? Some actually will use large diameter coax for the radiator or will use pipe to play with the L/D ratio or one really unique design uses a combination of lengths of coax to resonate the antenna in two closely spaced frequencies to broaden the antenna bandwidth.
I would like to point out that the handbook also has some great drawings on the current distribution in antennas.? Take note of the vertical that has a large inductor at the base or center and see the disturbance in the antenna current.? Visualize the current generating a field and you can see that these antennas may still deliver full power at the input of the transmission line, but all of that does not translate into current in the radiator.
As to the use of baluns and their mention in the handbook, of course baluns are mentioned for use with dipoles.? The dipole fed at the center or even off center are balanced loads.? If the antenna is fed with coax, then an imbalance is produced.? That translates to feed line radiation which may (most often does) affect the radiation of the antenna due to fields cancellation.? If one uses a balun to couple the balanced load with the unbalanced transmission line, balance is restored and radiation of the feed line is minimized.
As to comparing with antenna performance with dipoles or an isotropic radiator, that method is valid.? We know what an isotropic radiator field will look like and what load it presents.? To compare the antenna above with a full size half wave dipole at the same location and height would be useful for someone considering the design to match criteria at their QTH.? All of us have used various antennas for years.? We all have had contacts confirmed from DX stations, many with QRP, but that does not mean the antenna is better than others.? It means you can use that antenna to transmit to someone in that location sometimes.? Remember the old adage, "you can get a wet noodle to radiate, it does not mean you should or would use that all the time".
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Al Skierkiewicz
WB9UVJ
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I'm planning to venture into FT8 for the first time, and I'm going to use my FT-817.? I'm looking for a USB interface (w/ sound card), and it looks like the SignaLink SLUSB6PM might be the most popular solution.? Is that the right model # for the '817?? The SignaLink has been around a long time... maybe too long (I'm wondering if there's something newer and better that's in the same price range)??
If you're operating FT8 (or other digital modes) on your FT-817, which interface are you using?
Any suggestions/comments much appreciated.? Thanks much!
Larry, WA2VKG
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Pietro Molina
MARSALE
Bob AF9W