Re: results of new US antenna design - advice sought
N2VIP, not sure if you have read the other comments (Jeff KN8A & James M0JMX)???in this thread.?
I didn't claim to know either way (yes/no) if any ARRL (or any other US predecessor) publication covered this innovative antenna treatment, that I know from my fact finding was published in 1958, but I found references to earlier documents - and quote from the researcher/author that he is describing methods/practices used in WW2. I am yet to find any scholar article that outlines the theory by which this antenna system works, but of the various antenna analyzer programs I used, only 1 was able to calculate its lobes due to the "folding" requirements.?
I have asked senior?EEE and RF SME on this antenna, and they have a wealth?of design expertise in all things RF, Antenna for US branches and industries - and they all came up with exactly 0.00 knowledge on this design. In fact they contributed to studying it and doing their own Matlab models and for people who have dealt with sub-mm Wave EM analysis from VHF, one would think they know their stuff over 50 years.?
However I do know from my own personal background in South Asia, (I was S21X) the practice of "folding" HF antennas is common for military people?who deal with HF communications using backpack radios - just as Dr. Heavyside wrote. That's why - when I came across the article, searching for ham radio antennas for confined spaces - and I must stay some authors mentioned examples of such a mythical antenna in publications but never actually described it - I read it and visualized in my mind the first real military set (1970s at a military exhibition) I had a chance to ask about that had indeed a folded antenna. It did not have any inductors, or capacitive hats just flat flexible whips.
Now, since you believe there should be US coverage, if you could explain yourself where I missed such a mention in any of the ARRL (or any other US) handbooks I have seen from the 1970s onwards - that would be welcome addition to the knowledge bank.
On Mon, Feb 20, 2023 at 11:06 AM Ken N2VIP < ken@...> wrote: "N2VIP Which ARRL era publication would have published this?"
You said hams were discussing this antenna design for three decades,?
"a very old design HF antenna (post WW2 apparently from the documentation I have) that was rediscovered/tested by other hams in the 70s-80s, and 90s."
Are you telling me it was such a hot topic that it was discussed for 3 decades yet it never got written up for the Handbook, Antenna book, or QST? Ken, N2VIP ? No no, not a vertical. Horizontal orientation models only. There wasn't a name for this antenna in a 1958 article by? M. J. Heavyside, Ph.D (G2QM) he published theory and a report of his work.
So, others called it a variety of names. I wrote to UK hams abiut two years ago who sourced the article for me from their archives.??
N2VIP Which ARRL era publication would have published this??
So far the most apt name I have used in my modeling is non-inductive end-loaded antenna (NEDA)? comprising radiating and non-radatinv regions. Selecting 80m to 10m coverage I got 1ft H X 1ft w X 12ft L.?
L is horizontal dimension, total length.?
We made a third version of this system with a poly fabric embedded with antenna elements ... total dimensions 12ft L x 2.5ft W x 1 inch. It did work, better than others, but the wind blew the damn antenna post tripod over as we had created a sail that twists and turns with gusts. Well we have a lot of engineering to do on that one.?
Sorry I don't have any nice pictures to distribute as we are just experimenting with materials and all of our tests are cheaply made up of home depot products. The measurements are somewhat different between prototypes as we discover the cost of the parts we have to fabricate and make durable for long term outside use. It's should be a mature design for showing in a few months.?
73 de X
<snip>
|
Re: results of new US antenna design - advice sought
"N2VIP Which ARRL era publication would have published this?"
You said hams were discussing this antenna design for three decades,?
"a very old design HF antenna (post WW2 apparently from the documentation I have) that was rediscovered/tested by other hams in the 70s-80s, and 90s."
Are you telling me it was such a hot topic that it was discussed for 3 decades yet it never got written up for the Handbook, Antenna book, or QST? Ken, N2VIP On Feb 19, 2023, at 23:16, Samudra <samudra.haque@...> wrote:
? No no, not a vertical. Horizontal orientation models only. There wasn't a name for this antenna in a 1958 article by? M. J. Heavyside, Ph.D (G2QM) he published theory and a report of his work.
So, others called it a variety of names. I wrote to UK hams abiut two years ago who sourced the article for me from their archives.??
N2VIP Which ARRL era publication would have published this??
So far the most apt name I have used in my modeling is non-inductive end-loaded antenna (NEDA)? comprising radiating and non-radatinv regions. Selecting 80m to 10m coverage I got 1ft H X 1ft w X 12ft L.?
L is horizontal dimension, total length.?
We made a third version of this system with a poly fabric embedded with antenna elements ... total dimensions 12ft L x 2.5ft W x 1 inch. It did work, better than others, but the wind blew the damn antenna post tripod over as we had created a sail that twists and turns with gusts. Well we have a lot of engineering to do on that one.?
Sorry I don't have any nice pictures to distribute as we are just experimenting with materials and all of our tests are cheaply made up of home depot products. The measurements are somewhat different between prototypes as we discover the cost of the parts we have to fabricate and make durable for long term outside use. It's should be a mature design for showing in a few months.?
73 de X
<snip>
|
Re: results of new US antenna design - advice sought
Sam
The antenna does work. I struggled with keeping it all in line at times.
I tried a couple of ideas with a few different prototypes in my practical experiments
I may have it somewhere still
John VE3IPS -- John VE3IPS Radio is a Lifestyle not a Hobby Oprah added the ARRL Handbook to her list
|
Re: results of new US antenna design - advice sought
Jeff K8NA, It took about a year of design, several jigs and a two & three person effort to get the assembly working as the elements needed stringing with wires that always sagged until we came up with braces and fashioned a set of custom fasteners amd supports. Out goal was to make it transportable... for you know field day, shipping and storage.?
The mechanical SME and ham cursed me many times at changing requirements of course. This is a very difficult design not really suited for homebrew one offs IMHO.?
It sure sounds like this:
The date of the article is probably around 2003, given the comment here:
In the 70's and 80's my crowd played around a lot with metal tape on plastic sheet antennas, mostly VHF yagis.? Mechanical challenges were often challenging.
We tried a few fractal HF antennas, too:
interest and experimentation is novel HF designs seems to roughly correspond with sunspots, and since n5ese's work was at a time when solar activity is about what it is now (pretty good),? I think its probably a good time to experiment with one of these, if you're so inclined.
73, have fun! Jeff kn8a
|
Re: results of new US antenna design - advice sought
Thanks James M0JMX, the original article (1950s) is what I used to model practical antennas that can be made from now on. There were couple of versions, possibly a technical paper as well but I didnt have resources to locate those from the original institutions.?
It appears to be mentioned in this amusing radio club newsletter from 1963:
Apparently a version of it enabling an operator in Bradford to cause interference in Denmark using only 9w on top band from a loft-installed antenna!
Would be nice to see a copy of the original "Aerials for Confined Spaces" - RSGB - but doesn't appear to exist on the web.. Maybe a visit to a library is required?
73
James M0JMX
On Mon, Feb 20, 2023 at 9:18 AM Pietro Molina < pietro@...> wrote: Very interesting. I have a small space for the antennas and up to now I never had something for 80m.
How can we understand if we can build it with the equipment we have?
Pietro I2OIM
|
Re: results of new US antenna design - advice sought
On Mon, Feb 20, 2023 at 06:28 AM, Jeff wrote:
Mechanical challenges were often challenging.
Not enough coffee yet...
|
Re: results of new US antenna design - advice sought
It sure sounds like this:
The date of the article is probably around 2003, given the comment here:
In the 70's and 80's my crowd played around a lot with metal tape on plastic sheet antennas, mostly VHF yagis. Mechanical challenges were often challenging.
We tried a few fractal HF antennas, too:
interest and experimentation is novel HF designs seems to roughly correspond with sunspots, and since n5ese's work was at a time when solar activity is about what it is now (pretty good), I think its probably a good time to experiment with one of these, if you're so inclined.
73, have fun! Jeff kn8a
|
Re: results of new US antenna design - advice sought
It appears to be mentioned in this amusing radio club newsletter from 1963:
Apparently a version of it enabling an operator in Bradford to cause interference in Denmark using only 9w on top band from a loft-installed antenna!
Would be nice to see a copy of the original "Aerials for Confined Spaces" - RSGB - but doesn't appear to exist on the web.. Maybe a visit to a library is required?
73
James M0JMX
On Mon, Feb 20, 2023 at 9:18 AM Pietro Molina < pietro@...> wrote: Very interesting. I have a small space for the antennas and up to now I never had something for 80m.
How can we understand if we can build it with the equipment we have?
Pietro I2OIM
|
Re: results of new US antenna design - advice sought
Very interesting. I have a small space for the antennas and up to now I never had something for 80m.
How can we understand if we can build it with the equipment we have?
Pietro I2OIM
|
Re: results of new US antenna design - advice sought
Correction:
NEDA = non-inductive end loaded dipole antenna.?
That's pretty much the theory of the system I can figure out. I wrote GNU octave code to produce geometry and then did antenna analysis on the geometry.?
No no, not a vertical. Horizontal orientation models only. There wasn't a name for this antenna in a 1958 article by? M. J. Heavyside, Ph.D (G2QM) he published theory and a report of his work.
So, others called it a variety of names. I wrote to UK hams abiut two years ago who sourced the article for me from their archives.??
N2VIP Which ARRL era publication would have published this??
So far the most apt name I have used in my modeling is non-inductive end-loaded antenna (NEDA)? comprising radiating and non-radatinv regions. Selecting 80m to 10m coverage I got 1ft H X 1ft w X 12ft L.?
L is horizontal dimension, total length.?
We made a third version of this system with a poly fabric embedded with antenna elements ... total dimensions 12ft L x 2.5ft W x 1 inch. It did work, better than others, but the wind blew the damn antenna post tripod over as we had created a sail that twists and turns with gusts. Well we have a lot of engineering to do on that one.?
Sorry I don't have any nice pictures to distribute as we are just experimenting with materials and all of our tests are cheaply made up of home depot products. The measurements are somewhat different between prototypes as we discover the cost of the parts we have to fabricate and make durable for long term outside use. It's should be a mature design for showing in a few months.?
73 de X On Sun, Feb 19, 2023, 22:51 Ken N2VIP < ken@...> wrote: Apparently it's a type of vertical (1' x 1' x 12').
Is there a reason to think this design is not included in the ARRL publications of the era Ken, N2VIP ?What general type of antenna is it?
Joe n1khb
On Sun, Feb 19, 2023 at 9:39 PM, Samudra Hi, ? FT-817 QRP users, I am one of the developers of ?a modern incarnation of a very old design HF antenna (post WW2 apparently from the documentation I have) that was rediscovered/tested by other hams in the 70s-80s, and 90s. But then it was left alone AFAIK. We will soon have it on the air with my FT-817ND radio that I repaired a year plus ago, with the help of this forum members (Thank you). Our test cases will be SSB voice, and FT8 or other digital modes over a weekend coming up. Looking for regional contacts to try scheduled tests. ? In the DC/MD/VA region of US, I worked with a few business colleagues/ham radio operators to design/test/develop and fabricate working prototypes. Three versions are in testing now. What I am hoping is someone interested in antenna testing/fabrication will be able to indicate if what we are getting with an MFJ antenna analyzer and a MFJ antenna tuner (all we have in the field, but I have more equipment in my RF test lab – not at the placed where the antenna is being fielded) is good or not: ? 3.750 MHz ~ 1.0-1.1 SWR 7.010 MHz ~ 1.1-1.2 SWR 14.200~250 MHz – 1.3 SWR … 28 MHz – 1.2x SWR ? These were the first trials, with the fully assembled kit about 6 feet a.g.l. Total dimension is approximately: 1ft x 1ft x 12ft. It’s a geometrically complex antenna design, that hurts most antenna analyzing software. We haven’t got the lifting system in place to erect it safely to about 20 feet a.g.l. so this is the best we can do for now. ? Any comments on the statistics I am presenting welcome. I was not expecting so low SWR and we haven’t tried with a live transceiver yet. But there are very distinct notches and our dimensions of the radiation region was even bang on from antenna modeling theory with some margin. Feeder was a 50 ohm coax to manual antenna tuner unit of about 25ft length. ? We are wondering if it would be interesting to any with small space for antennas? What are your thoughts and requirements on packaging/support/reliability ? It’s becoming a challenge to source all parts at low cost and yet have good manufacturability and repeatability with the complex measurements mechanical and electrical per the design. ? 73 de N3RDX Washington, DC
|
Re: results of new US antenna design - advice sought
No no, not a vertical. Horizontal orientation models only. There wasn't a name for this antenna in a 1958 article by? M. J. Heavyside, Ph.D (G2QM) he published theory and a report of his work.
So, others called it a variety of names. I wrote to UK hams abiut two years ago who sourced the article for me from their archives.??
N2VIP Which ARRL era publication would have published this??
So far the most apt name I have used in my modeling is non-inductive end-loaded antenna (NEDA)? comprising radiating and non-radatinv regions. Selecting 80m to 10m coverage I got 1ft H X 1ft w X 12ft L.?
L is horizontal dimension, total length.?
We made a third version of this system with a poly fabric embedded with antenna elements ... total dimensions 12ft L x 2.5ft W x 1 inch. It did work, better than others, but the wind blew the damn antenna post tripod over as we had created a sail that twists and turns with gusts. Well we have a lot of engineering to do on that one.?
Sorry I don't have any nice pictures to distribute as we are just experimenting with materials and all of our tests are cheaply made up of home depot products. The measurements are somewhat different between prototypes as we discover the cost of the parts we have to fabricate and make durable for long term outside use. It's should be a mature design for showing in a few months.?
73 de X
On Sun, Feb 19, 2023, 22:51 Ken N2VIP < ken@...> wrote: Apparently it's a type of vertical (1' x 1' x 12').
Is there a reason to think this design is not included in the ARRL publications of the era Ken, N2VIP ?What general type of antenna is it?
Joe n1khb
On Sun, Feb 19, 2023 at 9:39 PM, Samudra Hi, ? FT-817 QRP users, I am one of the developers of ?a modern incarnation of a very old design HF antenna (post WW2 apparently from the documentation I have) that was rediscovered/tested by other hams in the 70s-80s, and 90s. But then it was left alone AFAIK. We will soon have it on the air with my FT-817ND radio that I repaired a year plus ago, with the help of this forum members (Thank you). Our test cases will be SSB voice, and FT8 or other digital modes over a weekend coming up. Looking for regional contacts to try scheduled tests. ? In the DC/MD/VA region of US, I worked with a few business colleagues/ham radio operators to design/test/develop and fabricate working prototypes. Three versions are in testing now. What I am hoping is someone interested in antenna testing/fabrication will be able to indicate if what we are getting with an MFJ antenna analyzer and a MFJ antenna tuner (all we have in the field, but I have more equipment in my RF test lab – not at the placed where the antenna is being fielded) is good or not: ? 3.750 MHz ~ 1.0-1.1 SWR 7.010 MHz ~ 1.1-1.2 SWR 14.200~250 MHz – 1.3 SWR … 28 MHz – 1.2x SWR ? These were the first trials, with the fully assembled kit about 6 feet a.g.l. Total dimension is approximately: 1ft x 1ft x 12ft. It’s a geometrically complex antenna design, that hurts most antenna analyzing software. We haven’t got the lifting system in place to erect it safely to about 20 feet a.g.l. so this is the best we can do for now. ? Any comments on the statistics I am presenting welcome. I was not expecting so low SWR and we haven’t tried with a live transceiver yet. But there are very distinct notches and our dimensions of the radiation region was even bang on from antenna modeling theory with some margin. Feeder was a 50 ohm coax to manual antenna tuner unit of about 25ft length. ? We are wondering if it would be interesting to any with small space for antennas? What are your thoughts and requirements on packaging/support/reliability ? It’s becoming a challenge to source all parts at low cost and yet have good manufacturability and repeatability with the complex measurements mechanical and electrical per the design. ? 73 de N3RDX Washington, DC
|
Re: results of new US antenna design - advice sought
Apparently it's a type of vertical (1' x 1' x 12').
Is there a reason to think this design is not included in the ARRL publications of the era Ken, N2VIP
toggle quoted message
Show quoted text
On Feb 19, 2023, at 21:45, Joseph Wonoski via groups.io <N1KHB@...> wrote:
?What general type of antenna is it?
Joe n1khb
On Sun, Feb 19, 2023 at 9:39 PM, Samudra <samudra.haque@...> wrote: Hi, ? FT-817 QRP users, I am one of the developers of ?a modern incarnation of a very old design HF antenna (post WW2 apparently from the documentation I have) that was rediscovered/tested by other hams in the 70s-80s, and 90s. But then it was left alone AFAIK. We will soon have it on the air with my FT-817ND radio that I repaired a year plus ago, with the help of this forum members (Thank you). Our test cases will be SSB voice, and FT8 or other digital modes over a weekend coming up. Looking for regional contacts to try scheduled tests. ? In the DC/MD/VA region of US, I worked with a few business colleagues/ham radio operators to design/test/develop and fabricate working prototypes. Three versions are in testing now. What I am hoping is someone interested in antenna testing/fabrication will be able to indicate if what we are getting with an MFJ antenna analyzer and a MFJ antenna tuner (all we have in the field, but I have more equipment in my RF test lab – not at the placed where the antenna is being fielded) is good or not: ? 3.750 MHz ~ 1.0-1.1 SWR 7.010 MHz ~ 1.1-1.2 SWR 14.200~250 MHz – 1.3 SWR … 28 MHz – 1.2x SWR ? These were the first trials, with the fully assembled kit about 6 feet a.g.l. Total dimension is approximately: 1ft x 1ft x 12ft. It’s a geometrically complex antenna design, that hurts most antenna analyzing software. We haven’t got the lifting system in place to erect it safely to about 20 feet a.g.l. so this is the best we can do for now. ? Any comments on the statistics I am presenting welcome. I was not expecting so low SWR and we haven’t tried with a live transceiver yet. But there are very distinct notches and our dimensions of the radiation region was even bang on from antenna modeling theory with some margin. Feeder was a 50 ohm coax to manual antenna tuner unit of about 25ft length. ? We are wondering if it would be interesting to any with small space for antennas? What are your thoughts and requirements on packaging/support/reliability ? It’s becoming a challenge to source all parts at low cost and yet have good manufacturability and repeatability with the complex measurements mechanical and electrical per the design. ? 73 de N3RDX Washington, DC
|
Re: results of new US antenna design - advice sought
What general type of antenna is it?
Joe n1khb
On Sun, Feb 19, 2023 at 9:39 PM, Samudra <samudra.haque@...> wrote: Hi, ? FT-817 QRP users, I am one of the developers of ?a modern incarnation of a very old design HF antenna (post WW2 apparently from the documentation I have) that was rediscovered/tested by other hams in the 70s-80s, and 90s. But then it was left alone AFAIK. We will soon have it on the air with my FT-817ND radio that I repaired a year plus ago, with the help of this forum members (Thank you). Our test cases will be SSB voice, and FT8 or other digital modes over a weekend coming up. Looking for regional contacts to try scheduled tests. ? In the DC/MD/VA region of US, I worked with a few business colleagues/ham radio operators to design/test/develop and fabricate working prototypes. Three versions are in testing now. What I am hoping is someone interested in antenna testing/fabrication will be able to indicate if what we are getting with an MFJ antenna analyzer and a MFJ antenna tuner (all we have in the field, but I have more equipment in my RF test lab – not at the placed where the antenna is being fielded) is good or not: ? 3.750 MHz ~ 1.0-1.1 SWR 7.010 MHz ~ 1.1-1.2 SWR 14.200~250 MHz – 1.3 SWR … 28 MHz – 1.2x SWR ? These were the first trials, with the fully assembled kit about 6 feet a.g.l. Total dimension is approximately: 1ft x 1ft x 12ft. It’s a geometrically complex antenna design, that hurts most antenna analyzing software. We haven’t got the lifting system in place to erect it safely to about 20 feet a.g.l. so this is the best we can do for now. ? Any comments on the statistics I am presenting welcome. I was not expecting so low SWR and we haven’t tried with a live transceiver yet. But there are very distinct notches and our dimensions of the radiation region was even bang on from antenna modeling theory with some margin. Feeder was a 50 ohm coax to manual antenna tuner unit of about 25ft length. ? We are wondering if it would be interesting to any with small space for antennas? What are your thoughts and requirements on packaging/support/reliability ? It’s becoming a challenge to source all parts at low cost and yet have good manufacturability and repeatability with the complex measurements mechanical and electrical per the design. ? 73 de N3RDX Washington, DC
|
Re: results of new US antenna design - advice sought
Can you ship a picture or drawing. Would help to visualize. Also forwarded to another group of smarter hams.?
W4DBL?
Doug Lynch
President?
Aries International, LLC
?
D: +1-321-415-2191
M:?+1-478-318-2655
?
E: Doug@...?
Port Orange, FL
toggle quoted message
Show quoted text
On Feb 19, 2023, at 21:39, Samudra via groups.io <samudra.haque@...> wrote:
?
Hi,
?
FT-817 QRP users, I am one of the developers of ?a modern incarnation of a very old design HF antenna (post WW2 apparently from the documentation I have) that was rediscovered/tested by other hams in the 70s-80s, and 90s. But then it was
left alone AFAIK. We will soon have it on the air with my FT-817ND radio that I repaired a year plus ago, with the help of this forum members (Thank you). Our test cases will be SSB voice, and FT8 or other digital modes over a weekend coming up. Looking for
regional contacts to try scheduled tests.
?
In the DC/MD/VA region of US, I worked with a few business colleagues/ham radio operators to design/test/develop and fabricate working prototypes. Three versions are in testing now. What I am hoping is someone interested in antenna testing/fabrication
will be able to indicate if what we are getting with an MFJ antenna analyzer and a MFJ antenna tuner (all we have in the field, but I have more equipment in my RF test lab – not at the placed where the antenna is being fielded) is good or not:
?
3.750 MHz ~ 1.0-1.1 SWR
7.010 MHz ~ 1.1-1.2 SWR
14.200~250 MHz – 1.3 SWR
…
28 MHz – 1.2x SWR
?
These were the first trials, with the fully assembled kit about 6 feet a.g.l. Total dimension is approximately: 1ft x 1ft x 12ft. It’s a geometrically complex antenna design, that hurts most antenna analyzing software. We haven’t got the
lifting system in place to erect it safely to about 20 feet a.g.l. so this is the best we can do for now.
?
Any comments on the statistics I am presenting welcome. I was not expecting so low SWR and we haven’t tried with a live transceiver yet. But there are very distinct notches and our dimensions of the radiation region was even bang on from
antenna modeling theory with some margin. Feeder was a 50 ohm coax to manual antenna tuner unit of about 25ft length.
?
We are wondering if it would be interesting to any with small space for antennas? What are your thoughts and requirements on packaging/support/reliability ? It’s becoming a challenge to source all parts at low cost and yet have good manufacturability
and repeatability with the complex measurements mechanical and electrical per the design.
?
73 de N3RDX
Washington, DC
|
results of new US antenna design - advice sought
Hi, ? FT-817 QRP users, I am one of the developers of ?a modern incarnation of a very old design HF antenna (post WW2 apparently from the documentation I have) that was rediscovered/tested by other hams in the 70s-80s, and 90s. But then it was left alone AFAIK. We will soon have it on the air with my FT-817ND radio that I repaired a year plus ago, with the help of this forum members (Thank you). Our test cases will be SSB voice, and FT8 or other digital modes over a weekend coming up. Looking for regional contacts to try scheduled tests. ? In the DC/MD/VA region of US, I worked with a few business colleagues/ham radio operators to design/test/develop and fabricate working prototypes. Three versions are in testing now. What I am hoping is someone interested in antenna testing/fabrication will be able to indicate if what we are getting with an MFJ antenna analyzer and a MFJ antenna tuner (all we have in the field, but I have more equipment in my RF test lab – not at the placed where the antenna is being fielded) is good or not: ? 3.750 MHz ~ 1.0-1.1 SWR 7.010 MHz ~ 1.1-1.2 SWR 14.200~250 MHz – 1.3 SWR … 28 MHz – 1.2x SWR ? These were the first trials, with the fully assembled kit about 6 feet a.g.l. Total dimension is approximately: 1ft x 1ft x 12ft. It’s a geometrically complex antenna design, that hurts most antenna analyzing software. We haven’t got the lifting system in place to erect it safely to about 20 feet a.g.l. so this is the best we can do for now. ? Any comments on the statistics I am presenting welcome. I was not expecting so low SWR and we haven’t tried with a live transceiver yet. But there are very distinct notches and our dimensions of the radiation region was even bang on from antenna modeling theory with some margin. Feeder was a 50 ohm coax to manual antenna tuner unit of about 25ft length. ? We are wondering if it would be interesting to any with small space for antennas? What are your thoughts and requirements on packaging/support/reliability ? It’s becoming a challenge to source all parts at low cost and yet have good manufacturability and repeatability with the complex measurements mechanical and electrical per the design. ? 73 de N3RDX Washington, DC
|
Re: FS W4RT One Board Filter OBF-817
Complete with both filters on board, already sold?
|
Re: FS W4RT One Board Filter OBF-817
|
Re: FS W4RT One Board Filter OBF-817
Saad did you sell this?? More info please too alpinewarren@...?if not 73!? AB6YA
|
Those particular driver FET's ae easy to replace. They are surface-mount, but they are SOT-89 cases. Just use some solder wick and the edge of an X-Acto knife to pry the part loose while heating the soldered pins.
The FT-817 uses 2SK2975 FET's as the main power output devices. THOSE are quite a bit more difficult to replace, as they are soldered underneath the device. Probably requires a small heat gun to remove a bad device and solder in a new one. The FT-857 and FT-897 put out a lot more power, so those use the 2SK2975 as the drivers and the 2SK2973 as pre-drivers.
73, Zack W9SZ
On Fri, Feb 17, 2023 at 1:59 PM Steven Greenfield AE7HD via <alienrelics= [email protected]> wrote:
It's the drivers I'm replacing, not the finals. But I figured I'd be checking/setting the currents for the drivers, predrivers, and outputs, since I have no idea why these drivers burned up.
--
Steven J Greenfield AE7HD
|
I also discovered the audio output is very weak, so this radio has multiple issues. Still waiting on the drivers, then I'll scope out the audio problem.
Not excited that it uses a surface mount audio output that is packed in tight. Not ordering any more parts until I confirm where the audio problem is at.
--
Steven J Greenfield AE7HD
|
John
Pietro Molina
Doug Lynch NNJ4EM