In article ,
"Ralph Mowery" wrote:

"Tom W3TDH" wrote in message
...
I am going to declare myself lost on this one so please be patient. I had
though I had addressed these issues when I said I was using a DCI Dual
Band Filter and Diplexer. Is the DCI combination filter and diplexer
insufficient to protect the two radios from each other? DCI claimed it
would be. The model number is DCI-146-444-DX-DB. The web sight were it
is listed is
http://www.dci.ca/?Section=Products&SubSection=Amateur. If I need to add
Duplexers it is practical to do because the mobile ones available used are
manageable money. If there is a real chance for damage in the event .of
simultaneous transmission then I will need to add circulators and dummy
loads to the output of both radios. That will end up being a little
pricy.


That DCI should be plenty to protect the two rigs. You may have a desense
on the 440 receiver if it on a near 3 rd harmonic of the 144 transmiter. It
won't be enough to cause any damage, just enough to block the 440 receiver.

I agree that you are not likely to damage a radio. The common duplexer
(or triplexer) is often used to connect a single multi-band antenna to
multiple connectors of a multi-band radio, which is essentially multiple
radios in a single package. The difference between this and what you
are planning, is that the multi-band radio is usually not used for
simultaneous reception and transmission. Or at least you would accept
some desensitization if it occurred.

You can choose frequencies such that the third harmonic of the Two Meter
frequency is not in the IF passband of the 440 receiver, but you are
likely have overloading of the receiver's broad front end. (You may
also have some overloading of the Two Meter radio due to the amount of
power involved.)

That said, go ahead and try it. It may work well enough to meet your
needs. If it does not work out, the alternative is a "real" repeater.

One advantage of a repeater, is that local users can hear each other.
With your Hot Spot, local users are talking simplex.

73,
Fred
K4DII

Fred McKenzie wrote:
I agree that you are not likely to damage a radio. The common duplexer
(or triplexer) is often used to connect a single multi-band antenna to
multiple connectors of a multi-band radio, which is essentially multiple
radios in a single package. The difference between this and what you
are planning, is that the multi-band radio is usually not used for
simultaneous reception and transmission. Or at least you would accept
some desensitization if it occurred.

You can choose frequencies such that the third harmonic of the Two Meter
frequency is not in the IF passband of the 440 receiver, but you are
likely have overloading of the receiver's broad front end. (You may
also have some overloading of the Two Meter radio due to the amount of
power involved.)

I have heard this "armchair theorist" story many times, but I have
never experienced this problem with my 3-band Diamond and matching
triplexer. Sure I hear the harmonics full-scale when tuned that way,
but never any overloading let alone damage.

Maybe it is only a problem when using QRO.


I think it is more warranted to warn against collinear antennas that get
shipped in two parts. The connection is the weak point in the antenna.
Unfortunately it appears that for a 6/2/70 tribander it is the only
option. Normally they fail within a couple of years. Also on the high
bands there is severe fading in windy conditions because the entire
antenna bends too much.

My 2/70/23 tribander is in one piece and it does not have those defects.

On Thursday, March 12, 2015 at 11:41:23 PM UTC-4, Fred McKenzie wrote:
In article ,
"Ralph Mowery" wrote:

"Tom W3TDH" wrote in message
...
I am going to declare myself lost on this one so please be patient. I had
though I had addressed these issues when I said I was using a DCI Dual
Band Filter and Diplexer. Is the DCI combination filter and diplexer
insufficient to protect the two radios from each other? DCI claimed it
would be. The model number is DCI-146-444-DX-DB. The web sight were it
is listed is
http://www.dci.ca/?Section=Products&SubSection=Amateur. If I need to add
Duplexers it is practical to do because the mobile ones available used are
manageable money. If there is a real chance for damage in the event ..of
simultaneous transmission then I will need to add circulators and dummy
loads to the output of both radios. That will end up being a little
pricy.


That DCI should be plenty to protect the two rigs. You may have a desense
on the 440 receiver if it on a near 3 rd harmonic of the 144 transmiter.. It
won't be enough to cause any damage, just enough to block the 440 receiver.

I agree that you are not likely to damage a radio. The common duplexer
(or triplexer) is often used to connect a single multi-band antenna to
multiple connectors of a multi-band radio, which is essentially multiple
radios in a single package. The difference between this and what you
are planning, is that the multi-band radio is usually not used for
simultaneous reception and transmission. Or at least you would accept
some desensitization if it occurred.

You can choose frequencies such that the third harmonic of the Two Meter
frequency is not in the IF passband of the 440 receiver, but you are
likely have overloading of the receiver's broad front end. (You may
also have some overloading of the Two Meter radio due to the amount of
power involved.)

That said, go ahead and try it. It may work well enough to meet your
needs. If it does not work out, the alternative is a "real" repeater.

One advantage of a repeater, is that local users can hear each other.
With your Hot Spot, local users are talking simplex.

73,
Fred
K4DII

Fred

As I already said I am not totally conversant with D-STAR. I was under the impression that the persons participating in any given QSO could hear each other over the access point they were using. I had pictured it as somewhat akin to the remote receivers on our club's analog FM repeater in that the other users on the QSO would hear the conversation over the repeaters output. Our D-STAR repeater is located in Germantown and I do not actually know what it's effective range is. We operate six different sites with four repeaters, four remote receivers with radio links back to the analog two meter repeater, and two APRS digipeaters. In addition to those sites we will have several members hosting D-STAR hot spots in order to fill in the edges of our service area that are outside the effective receive range of portable radios. Those using mobile or base station radio will, hopefully, be able to raise the repeater without resorting to one of the hot spots We can make changes to the location of the various elements of our repeater system including the location of the D-STAR repeater itself if that is needed to allow all users to hear the conversation.

On the harmonic de-sensing issue I can purchase a DCI low pass filter that cuts off at 160MHz if that becomes a problem. It would be inserted between the two meter radio and the filter/diplexer so that the harmonic would not reach the diplexer at all. Part of this question affects operations well beyond my home location. The county ARES unit is gearing up to support hospital emergency communications in our area. Our first client hospital purchased an Icom IC-7100 transceiver for the hospital station. If that remains the only transmitter at the hospital's EOC then the use of directly connected multi band antennas will work fine. But if the hospital discovers that it needs more than one mode or frequency to be used at the same time then our team will have to devise a Diplexing setup in order to keep the two radios from clobbering each other. I could see them needing both local tactical voice and medium range digital at the same time in a real disaster situation.

In the Mid Atlantic region the most common natural disaster with region wide effects are severe ice storms. Since I moved to three land in 1980 we have had three such storms that have wiped out communications infrastructure over wide portions of our region. It usually takes at least a week to get all of the wires and fibers back up in the air. Were about fifteen years out from our last bad one so we're about due. The hospitals have learned that continuing to operate when it is very difficult to talk to anyone that is not on campus is more than challenging. That's why I think they are going to want more than one communications pathway available to them and nothing carries long documents as quickly and accurately as digital.

Thanks again for taking the time to help on this.

--
Tom Horne W3TDH

Tom,
You have too many of the same band antenna's concentrated in one place.
No matter how hard you try, they aren't going to play nice with each other.
I read 14 posts and no one gave an even close right answer to your question.
The answer is that you need to construct a tower, no less than 100', near your house in order to even try to do what you wish to do.
Even then, you will need feet of separation vertically in order to get the antenna's to play nice with each other.
Your SWR is going to be all messed up, because you have too many of the same antenna's in the same proximity.

The only good 6 / 2 / 70 cm antenna that I could recommend would be the Diamond v2000. This is the only antenna that I am aware of that has a decent amount of gain - if you want to call it that, along with being semi resonant on all three bands.

What you are doing is back-feeding everything that you transmit back into the receive of the front ends of all of the radios in your shack when any one radio transmits. Unless it is in your budget to replace all those radios on a semi annual schedule, you will eventually experience that each of those transceivers will eventually become deaf.

I have seen filters promoted in QST that allows two operators on two different bands to share a beam antenna with two transceivers, as long as each transceiver stays on it's band it is ok.

But there is a hell of a difference between 20 meters - 14 MHz - CW and 40 meters Phone.

Even though 70 cm is not a harmonic of 2m, and even though there is a heck of a disparity between 440 MHz and 146 MHZ there is always going to be problems when dealing with FM, and Digital modes.

I have to take your wife's side on this one!

Tell your club to go out and buy an acre of ground and put up a transmitter and a tower and put their packet and their D-Star crap on their tower, and then you can tune to their tower frequency if you so choose. You are killing not only all of your transceivers by what you are trying to do, but you are diminishing the range at which you yourself can operate...

If you can hear other repeaters / more than 20 miles away though all of that RF noise you have created, you will be lucky..

It doesn't matter if the radios are all turned on or off, as long as they are connected to the coax / antenna, they are still going to experience front end overload.

"Tom W3TDH" wrote in message
...[i]

As I already said I am not totally conversant with D-STAR. I was under the impression that the persons participating in any given QSO could hear each other over the access point they were using. I had pictured it as somewhat akin to the remote receivers on our club's analog FM repeater in that the other users on the QSO would hear the conversation over the repeaters output. Our D-STAR repeater is located in Germantown and I do not actually know what it's effective range is. We operate six different sites with four repeaters, four remote receivers with radio links back to the analog two meter repeater, and two APRS digipeaters. In addition to those sites we will have several members hosting D-STAR hot spots in order to fill in the edges of our service area that are outside the effective receive range of portable radios. Those using mobile or base station radio will, hopefully, be able to raise the repeater without resorting to one of the hot spots We can make changes to the location of the various elements of our repeater system including the location of the D-STAR repeater itself if that is needed to allow all users to hear the conversation.

On the harmonic de-sensing issue I can purchase a DCI low pass filter that cuts off at 160MHz if that becomes a problem. It would be inserted between the two meter radio and the filter/diplexer so that the harmonic would not reach the diplexer at all. Part of this question affects operations well beyond my home location. The county ARES unit is gearing up to support hospital emergency communications in our area. Our first client hospital purchased an Icom IC-7100 transceiver for the hospital station. If that remains the only transmitter at the hospital's EOC then the use of directly connected multi band antennas will work fine. But if the hospital discovers that it needs more than one mode or frequency to be used at the same time then our team will have to devise a Diplexing setup in order to keep the two radios from clobbering each other. I could see them needing both local tactical voice and medium range digital at the same time in a real disaster situation.

In the Mid Atlantic region the most common natural disaster with region wide effects are severe ice storms. Since I moved to three land in 1980 we have had three such storms that have wiped out communications infrastructure over wide portions of our region. It usually takes at least a week to get all of the wires and fibers back up in the air. Were about fifteen years out from our last bad one so we're about due. The hospitals have learned that continuing to operate when it is very difficult to talk to anyone that is not on campus is more than challenging. That's why I think they are going to want more than one communications pathway available to them and nothing carries long documents as quickly and accurately as digital.

Thanks again for taking the time to help on this.

--
Tom Horne W3TDH[/quote]

Tom,
The ICOM IC 7100 is a lousy choice for a all in one rig for what you are trying to do and I don't think that it is going to be sufficient for your needs. You need to have separate rigs for your UHF / VHF and your HF so one can be sending messages digitally while the other one is being used on FM phone to communicate with your Indians in the field.

You need to talk to the hospital and impress upon them that everything other then dealing with the other local hams, on a local basis is probably going to take place digitally on the HF, either 40 or 80 meters.

Find someone to put on a presentation for your group about NBEMS / FLDIGI
The Sunday morning net would be a good place for your group to start.
I'm sure that Dave KB3FXI would be more then happy to help, as time permits.
What you are going to find is that everything is going to run either through your section manager and The Phone Traffic Net, or ARES, or Races, or FLDIGI.

I'm not sure where you are located at, most of what I concern myself with is with the third region, but also participating on the State Wide - once a month net - RACES, Central and Western Region nets, along with the Saturday morning ARES nets and the late Sunday morning NBEMS nets.

What your group is going to find will be two fold.
First off - D-Star Sucks!
Second - with the advent of the new Yaesu System Fusion repeaters, that does a lot more then what D-Star does, the D-Star system is going to become defunct, while the System Fusion is going to be the Ex Post Facto once a emergency happens and the people in charge see's how good the System Fusion works and more people buys a radio.

The only thing D-Star had going for it was the fact that they gave repeaters and radios away and they gave the ARRL heaps of money to promote D-Star.
The ARRL pimps and panders for anyone or anything that puts more money into their coffers.

My replies are in line with information you have offered in order to help me in keeping my responses organized.

On Friday, March 13, 2015 at 10:13:04 PM UTC-4, Channel Jumper wrote:
Tom W3TDH;836715 Wrote:
I am looking for recommendations for a dual band antenna that will serve
two separate radios. The reason that I want to use a single antenna is
that I have a limited number of mounting points for antennas. At
present it will be hard for SWMBO; as in Rumpole's spouse, She Who Must
Be Obeyed; to tolerate the use of both our home's gable ends and the
chimney being used to support antennas. I am planning to replace my
Diamond X-30 with a triband vertical for Six, Two, and .7 Meters. The
chimney will then support a rotor aimed Two and .7 Meter beam. The
second gable end will support the Two meter / Seventy Centimeter dual
band vertical that I am asking for help in selecting.

One radio will be a two meter packet node which will be used as a
Winlink Radio Message Server. The other radio will be a UHF D-STAR
hotspot. I am willing to pay what is needed to to get the best antenna
for this application but I don't want to waste money ineffectively. So
the two meter radio will be in the 144 MHz portion of the band and I
don't yet actually know were the D-STAR hotspot will be run. I have a
DCI filter and diplexer to keep the two radios from actually knowing of
each others existence. Since a hotspot is not supposed to be a terribly
wide area installation I would imagine that I do not want an extremely
high gain antenna but I am perfectly open to be reeducated on that. The
difficulty is that I would guess that the Radio Message Server / Packet
would benefit from as much horizontal gain as can be achieved. I have a
home brewed collinear two meter J-Pole that has been a good performer on
two meters and presents a low SWR on 440 MHz. I have yet to master
antenna modeling but I would imagine; given all the warnings I have read
on line; that it has poor radiation pattern on UHF. Is it likely to be
too poor a performer for a hot spot on UHF?

I really am asking because I want to know. I am not looking for
encouragement to do something that will be ineffective. Thank you in
advance for any help you may be willing to offer.

--
Tom Horne W3TDH

Tom,
You have too many of the same band antenna's concentrated in one place.
No matter how hard you try, they aren't going to play nice with each
other.
I read 14 posts and no one gave an even close right answer to your
question.
The answer is that you need to construct a tower, no less than 100',
near your house in order to even try to do what you wish to do.
Even then, you will need feet of separation vertically in order to get
the antenna's to play nice with each other.

Would you please name a figure for the required vertical separation? If that figure is less than Thirty Feet then could you explain why one antenna at my home's ridge line and one twenty feet higher wouldn't be enough?

I have worked net control for the Marine Corps Marathon in Washington DC for several years now and we have not had problems running two very active Two Meter Nets with only ten feet of vertical separation between the two antennas on a Fifty Foot Tall AB-952/GRC-103 self jacking mast. We also had a receive only APRS receiver set up and had no missed packets when compared with WWW.APRS.FI. The APRS is down at 146.390 MHz and thus Two MHz away from the repeater pairs being used for the two race nets but the race nets were sometimes interlaced with each other with one frequency pair on standard Six Hundred KHz separation straddling one of the frequencies of the other nets repeater. We did not experience the kind of de-sensing or damage that you are warning me of. So what you are saying is at odds with most of the Net Control operations that I have seen at a large number of larger public service events. We have had Twenty Watt continuous output FM ATV repeaters co-located with a voice repeater with both on the Seventy Centimeter Band without the issues that you are reporting with a vertical separation of only ten feet between the two antennas.

Your SWR is going to be all messed up, because you have too many of the
same antenna's in the same proximity.

The antenna handbook says that two Wavelengths of separation from other metallic objects is sufficient to prevent de-tuning at VHF UHF frequencies. Are you saying that because the two antennas are co-resonant that the effect is that much worse.

The only good 6 / 2 / 70 cm antenna that I could recommend would be the
Diamond v2000. This is the only antenna that I am aware of that has a
decent amount of gain - if you want to call it that, along with being
semi resonant on all three bands.

What you are doing is back-feeding everything that you transmit back
into the receive of the front ends of all of the radios in your shack
when any one radio transmits. Unless it is in your budget to replace
all those radios on a semi annual schedule, you will eventually
experience that each of those transceivers will eventually become deaf.


Others have said that the DCI-146-444-DX-DB Diplexer and Dual Band Filter will provide sufficient isolation. Since you are saying that is not true would you mind explaining why?

I have seen filters promoted in QST that allows two operators on two
different bands to share a beam antenna with two transceivers, as long
as each transceiver stays on it's band it is ok.

But there is a hell of a difference between 20 meters - 14 MHz - CW and
40 meters Phone.

We have used such a filter set on our 20, 15, 10 Meter tribander for the last several field days with excellent results and no ill effects. Two of the transceivers used were my Yaesu FT-1000 and FT-857D. I have had no performance changes on either radio.

Even though 70 cm is not a harmonic of 2m, and even though there is a
heck of a disparity between 440 MHz and 146 MHZ there is always going to
be problems when dealing with FM, and Digital modes.

What kind of problems?

I have to take your wife's side on this one!

My Wife's objections are aesthetic. She doesn't want our home to look like a police precinct station when viewed from the street. So what exactly are you agreeing with her on.

Tell your club to go out and buy an acre of ground and put up a
transmitter and a tower and put their packet and their D-Star crap on
their tower, and then you can tune to their tower frequency if you so
choose. You are killing not only all of your transceivers by what you
are trying to do, but you are diminishing the range at which you
yourself can operate...

How am I accomplishing that exactly? I have already had several VHF UHF transceivers operating at the same time at my home without harm to any of the equipment. The only change I would be making here is that more than one transceiver would be operating on different bands on a multiband antenna using the DCI-146-444-DX-DB and/or other DCI Four Pole Band Pass Filters for isolation.

If you can hear other repeaters / more than 20 miles away though all of
that RF noise you have created, you will be lucky..

I've already done this with separate antennas at this location without any loss of range or intelligibility that I could discern. I have run the Baltimore Washington Skywarn net with the Radio Message Server Packet chirping away only twenty feet apart at the same height above ground level (AGL) without either one missing a beat. That includes a net that covered an activation for a tornado watch that actually produced three tornadoes and a very busy net. All of the repeats and fills were caused by over excited operators rather than by de-sensing.
It doesn't matter if the radios are all turned on or off, as long as
they are connected to the coax / antenna, they are still going to
experience front end overload.

--
Channel Jumper

I realize that I didn't say this previously but I do use grounding coaxial switches on my rigs and they are always in the shorted grounded condition when the radio that they are serving is turned off. I also have both Surge protectors on all my antenna coax entries and EMP protectors on all of the rigs. I don't see how enough energy to damage the rigs could get past the EMP Protectors.

--
Tom Horne W3TDH

On Saturday, March 14, 2015 at 5:07:37 AM UTC-4, Jeff wrote:
On 14/03/2015 01:48, Channel Jumper wrote:
Tom W3TDH;836715 Wrote:
I am looking for recommendations for a dual band antenna that will serve
two separate radios. The reason that I want to use a single antenna is
that I have a limited number of mounting points for antennas. At
present it will be hard for SWMBO; as in Rumpole's spouse, She Who Must
Be Obeyed; to tolerate the use of both our home's gable ends and the
chimney being used to support antennas. I am planning to replace my
Diamond X-30 with a triband vertical for Six, Two, and .7 Meters. The
chimney will then support a rotor aimed Two and .7 Meter beam. The
second gable end will support the Two meter / Seventy Centimeter dual
band vertical that I am asking for help in selecting.

One radio will be a two meter packet node which will be used as a
Winlink Radio Message Server. The other radio will be a UHF D-STAR
hotspot. I am willing to pay what is needed to to get the best antenna
for this application but I don't want to waste money ineffectively. So
the two meter radio will be in the 144 MHz portion of the band and I
don't yet actually know were the D-STAR hotspot will be run. I have a
DCI filter and diplexer to keep the two radios from actually knowing of
each others existence. Since a hotspot is not supposed to be a terribly
wide area installation I would imagine that I do not want an extremely
high gain antenna but I am perfectly open to be reeducated on that. The
difficulty is that I would guess that the Radio Message Server / Packet
would benefit from as much horizontal gain as can be achieved. I have a
home brewed collinear two meter J-Pole that has been a good performer on
two meters and presents a low SWR on 440 MHz. I have yet to master
antenna modeling but I would imagine; given all the warnings I have read
on line; that it has poor radiation pattern on UHF. Is it likely to be
too poor a performer for a hot spot on UHF?

I really am asking because I want to know. I am not looking for
encouragement to do something that will be ineffective. Thank you in
advance for any help you may be willing to offer.

--
Tom Horne W3TDH

Tom,
You have too many of the same band antenna's concentrated in one place.
No matter how hard you try, they aren't going to play nice with each
other.
I read 14 posts and no one gave an even close right answer to your
question.
The answer is that you need to construct a tower, no less than 100',
near your house in order to even try to do what you wish to do.
Even then, you will need feet of separation vertically in order to get
the antenna's to play nice with each other.
Your SWR is going to be all messed up, because you have too many of the
same antenna's in the same proximity.

The only good 6 / 2 / 70 cm antenna that I could recommend would be the
Diamond v2000. This is the only antenna that I am aware of that has a
decent amount of gain - if you want to call it that, along with being
semi resonant on all three bands.

What you are doing is back-feeding everything that you transmit back
into the receive of the front ends of all of the radios in your shack
when any one radio transmits. Unless it is in your budget to replace
all those radios on a semi annual schedule, you will eventually
experience that each of those transceivers will eventually become deaf.

I have seen filters promoted in QST that allows two operators on two
different bands to share a beam antenna with two transceivers, as long
as each transceiver stays on it's band it is ok.

But there is a hell of a difference between 20 meters - 14 MHz - CW and
40 meters Phone.

Even though 70 cm is not a harmonic of 2m, and even though there is a
heck of a disparity between 440 MHz and 146 MHZ there is always going to
be problems when dealing with FM, and Digital modes.

I have to take your wife's side on this one!

Tell your club to go out and buy an acre of ground and put up a
transmitter and a tower and put their packet and their D-Star crap on
their tower, and then you can tune to their tower frequency if you so
choose. You are killing not only all of your transceivers by what you
are trying to do, but you are diminishing the range at which you
yourself can operate...

If you can hear other repeaters / more than 20 miles away though all of
that RF noise you have created, you will be lucky..

It doesn't matter if the radios are all turned on or off, as long as
they are connected to the coax / antenna, they are still going to
experience front end overload.


What a complete load of hog wash!!

A dual band antenna and the DCI filter/diplexer will work just fine.
The DCI filter provides bandpass characteristics on both 2 & 70 and then
provides a single output. The filters provide more than adequate
isolation between radios to stop any damage for reasonable power levels.

You almost certainly will be able to hear the harmonics from the 2m tx
on 70 but the level will not cause any damage.

By the way Channel Jumper 70cms IS a harmonic of 2m, perhaps time to
brush up on your 3 times table.

Jeff



On Saturday, March 14, 2015 at 5:07:37 AM UTC-4, Jeff wrote:
On 14/03/2015 01:48, Channel Jumper wrote:
Tom W3TDH;836715 Wrote:
I am looking for recommendations for a dual band antenna that will serve
two separate radios. The reason that I want to use a single antenna is
that I have a limited number of mounting points for antennas. At
present it will be hard for SWMBO; as in Rumpole's spouse, She Who Must
Be Obeyed; to tolerate the use of both our home's gable ends and the
chimney being used to support antennas. I am planning to replace my
Diamond X-30 with a triband vertical for Six, Two, and .7 Meters. The
chimney will then support a rotor aimed Two and .7 Meter beam. The
second gable end will support the Two meter / Seventy Centimeter dual
band vertical that I am asking for help in selecting.

One radio will be a two meter packet node which will be used as a
Winlink Radio Message Server. The other radio will be a UHF D-STAR
hotspot. I am willing to pay what is needed to to get the best antenna
for this application but I don't want to waste money ineffectively. So
the two meter radio will be in the 144 MHz portion of the band and I
don't yet actually know were the D-STAR hotspot will be run. I have a
DCI filter and diplexer to keep the two radios from actually knowing of
each others existence. Since a hotspot is not supposed to be a terribly
wide area installation I would imagine that I do not want an extremely
high gain antenna but I am perfectly open to be reeducated on that. The
difficulty is that I would guess that the Radio Message Server / Packet
would benefit from as much horizontal gain as can be achieved. I have a
home brewed collinear two meter J-Pole that has been a good performer on
two meters and presents a low SWR on 440 MHz. I have yet to master
antenna modeling but I would imagine; given all the warnings I have read
on line; that it has poor radiation pattern on UHF. Is it likely to be
too poor a performer for a hot spot on UHF?

I really am asking because I want to know. I am not looking for
encouragement to do something that will be ineffective. Thank you in
advance for any help you may be willing to offer.

--
Tom Horne W3TDH

Tom,
You have too many of the same band antenna's concentrated in one place.
No matter how hard you try, they aren't going to play nice with each
other.
I read 14 posts and no one gave an even close right answer to your
question.
The answer is that you need to construct a tower, no less than 100',
near your house in order to even try to do what you wish to do.
Even then, you will need feet of separation vertically in order to get
the antenna's to play nice with each other.
Your SWR is going to be all messed up, because you have too many of the
same antenna's in the same proximity.

The only good 6 / 2 / 70 cm antenna that I could recommend would be the
Diamond v2000. This is the only antenna that I am aware of that has a
decent amount of gain - if you want to call it that, along with being
semi resonant on all three bands.

What you are doing is back-feeding everything that you transmit back
into the receive of the front ends of all of the radios in your shack
when any one radio transmits. Unless it is in your budget to replace
all those radios on a semi annual schedule, you will eventually
experience that each of those transceivers will eventually become deaf.

I have seen filters promoted in QST that allows two operators on two
different bands to share a beam antenna with two transceivers, as long
as each transceiver stays on it's band it is ok.

But there is a hell of a difference between 20 meters - 14 MHz - CW and
40 meters Phone.

Even though 70 cm is not a harmonic of 2m, and even though there is a
heck of a disparity between 440 MHz and 146 MHZ there is always going to
be problems when dealing with FM, and Digital modes.

I have to take your wife's side on this one!

Tell your club to go out and buy an acre of ground and put up a
transmitter and a tower and put their packet and their D-Star crap on
their tower, and then you can tune to their tower frequency if you so
choose. You are killing not only all of your transceivers by what you
are trying to do, but you are diminishing the range at which you
yourself can operate...

If you can hear other repeaters / more than 20 miles away though all of
that RF noise you have created, you will be lucky..

It doesn't matter if the radios are all turned on or off, as long as
they are connected to the coax / antenna, they are still going to
experience front end overload.


What a complete load of hog wash!!

A dual band antenna and the DCI filter/diplexer will work just fine.
The DCI filter provides bandpass characteristics on both 2 & 70 and then
provides a single output. The filters provide more than adequate
isolation between radios to stop any damage for reasonable power levels.

You almost certainly will be able to hear the harmonics from the 2m tx
on 70 but the level will not cause any damage.

By the way Channel Jumper 70cms IS a harmonic of 2m, perhaps time to
brush up on your 3 times table.

Jeff

Jeff

May I ask that you cool your jets a little. Please turn off the afterburners and stick to the questions that I'm asking. I don't want to be a focus of a flame war. I came here in the hope of getting good information and the task of sorting out conflicting advice is so much easier if I don't need to also filter out gratuitous feuding.

Your version of what is possible is attractive because it allows me to do what I want to do to support my clubs D-STAR project and provide a training resource for the ARES Hospital Emergency Net staff to become competent with Winlink.

I realize that there are some Hams that despise Winlink and all other automated store and forward systems. I will be doing everything I can to avoid interference to other Amateurs but since we are using this to support hospitals under emergency conditions I think that everyone can just suck it up and bare with the emergency traffic and whatever inconvenience it may generate. b

Would you please advise if the third harmonic issue is likely to be serious enough to require the use of a low pass filter between the two meter transceiver and the Diplexer/Band Pass Filter when using separate transmitters?

--
Tom Horne W3TDH

In article ,
Tom W3TDH wrote:

I was under the impression that the persons participating in any given QSO
could hear each other over the access point they were using. I had pictured
it as somewhat akin to the remote receivers on our club's analog FM repeater
in that the other users on the QSO would hear the conversation over the
repeaters output.

Tom-

The more you post, the more complicated it becomes!

What you describe sounds like a remote receiver for an existing
repeater, not a hot spot. The hot spot I have is a low power DVAP
operating on a simplex frequency. Yours might be equivalent, but using
a more powerful transmitter.

A hot spot does not connect to a repeater via RF. It connects via the
internet to another device. That device might be a D-STAR repeater, but
often it is a computer hosting a "reflector" that repeaters may also be
connected to.

If your hot spot is connected to the same reflector as the local
repeater, it would be possible for users to talk into the hot spot and
listen to the repeater output. But that would be a split frequency
setup for the radio.

As I said, go ahead and try what you had planned. It will work to some
extent, and will help you get your feet wet.

73,
Fred
K4DII

Tom,

Please see inlined...

On 3/14/2015 1:17 PM, Tom W3TDH wrote:

May I ask that you cool your jets a little. Please turn off the
afterburners and stick to the questions that I'm asking. I don't
want to be a focus of a flame war. I came here in the hope of
getting good information and the task of sorting out conflicting
advice is so much easier if I don't need to also filter out
gratuitous feuding.

If you followed this group before posting (always a good idea), you will
see that is pretty normal here. If you're going to post, you can expect
both good and bad advice. And some people (like Channel Jumper - who
probably isn't even a ham) are so far off with every post you can expect
a flame war.

But then that is true of almost every place on the Internet.

Your version of what is possible is attractive because it allows me
to do what I want to do to support my clubs D-STAR project and
provide a training resource for the ARES Hospital Emergency Net staff
to become competent with Winlink.

I realize that there are some Hams that despise Winlink and all other
automated store and forward systems. I will be doing everything I can
to avoid interference to other Amateurs but since we are using this to
support hospitals under emergency conditions I think that everyone can
just suck it up and bare with the emergency traffic and whatever
inconvenience it may generate. b


You are required by law to avoid interference. But you also need to
understand what constitutes emergency traffic to the FCC. For that to
occur, there must be an IMMEDIATE threat to life and/or property. An
example would be reporting an automobile accident, especially one
requiring immediate medical attention.

It does NOT include 99% of the traffic being passed during an emergency.
In the 19 years I've been a member of MoCo ARES/RACES (including the
Hospital Net), we have NEVER had emergency traffic passed during a
callout. Of course, I could also say that of most of the emergencies
I've been involved in in 47 years as a ham. The only times I can think
of that I've been involved in true emergency traffic during a callout
was when aiding search and rescue after tornadoes.

Just because it's a hospital net does not constitute emergency traffic.

So, while hams in the area will voluntarily yield the frequency, there
is no requirement for them to do so, and any interference would be a
violation.

Would you please advise if the third harmonic issue is likely to be
serious enough to require the use of a low pass filter between the
two meter transceiver and the Diplexer/Band Pass Filter when using
separate transmitters?


Your diplexer should handle that well enough. What would be more of a
concern to me would be just the spurious radiation around the shack.
It's possible that could cause some desense, but I wouldn't expect it to
be significant.

--
Tom Horne W3TDH


Your sig separator is broken. It needs to be exactly
hyphen-hyphen-space-newline. You're missing the space.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

On 3/15/2015 5:50 AM, Brian Reay wrote:
Tom W3TDH wrote:


Would you please advise if the third harmonic issue is likely to be
serious enough to require the use of a low pass filter between the two
meter transceiver and the Diplexer/Band Pass Filter when using separate transmitters?


It depends on your tx.

I've never required filters nor heard of their being required.

Remember, you would need to be listening on the 3rd Rx harmonic, or 'close'
to it for the rx to suffer and the harmonic should get several 10s of dB
down relative to tell 2m carrier.


Brian,

Yes, it will be several 10s of dB down - but that can still be
sufficient to be heard in (and potentially desense) a near-by receiver.
It doesn't take a lot of signal if it's within the receiver's passband.

But Tom's diplexer should handle this easily.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================