Cross Band Repeat With HT - How Practical For Simplex?

[KR7CQ]

Some of the most interesting ham radio in my area, is on 2 meter simplex, and I am an active person who is moving around a lot when at home. Because of this, I am considering using 70 cm between my FT-60R and a Kenwood TM-V71A doing crossband to communicate with other stations on a popular 2 meter simplex frequency. This would allow me to work in my shop or the yard, or be anywhere in my house, while having the power, range, and reception of my base station.

I would run minimum power on UHF both directions, though I know that a high gain antenna 35 feet up on my mast is going to have serious reach anyway. Because of this I know that I will need to use the CW ID feature that sends regular IDs on both the UHF simplex frequency (from the base unit), and on the 2 meter simplex frequency, so that people are not hearing a bunch of guys talking to one guy who never ID's if they are monitoring UHF where my little HT signal can't reach them but the base can (IMO very likely to occur in Phoenix). My HT wouldn't ever be more than 75' from the base.

Assuming that this would be fully legal (correct me if I am missing anything there), my questions:

What are the downsides from a practical standpoint? Is there enough lag time waiting for radios that transmissions are delayed too much for efficient conversation on simplex where people typically respond very quickly after the other station is done with his TX (as opposed to repeater work)? Would the CW ID be annoying to people doing round tables (who don't have much dead air), by way of ID'ing over people every ten minutes, or is it a low enough audio level that it would likely be tolerable? Keep in mind that while the operators on this frequency obey the law, they are very casual and informal for the most part. Would long-time hams who are on the casual side likely find the CW ID annoying? Will this setup lead to an early death of the radio with such a hefty duty cycle and with long conversations? Are there other downsides I'm missing?

 

[evfd1625]

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Well if you are only receiving on the 2m freq then you shouldn't have to use the CW ID at all on the 2m side. I would only id on the UHF side. You can ID by voice when transmitting from the portable to the repeater and it will come out on the 2m simplex freq also. As far as duty cycle, get a good fan and make sure it is on all the time on the heat sinks.

 

[Token]

I don’t have the TM-V71 but I do exactly what you are describing all the time on my TM-742A, my FT8900R, or my TS2000X (in fact, the TS2kX is in the house for only this purpose). It is very useful. I also do it from my vehicle mounted TS2000X when I am mobile, for example when I park someplace and hike the area. The nice thing about the TS2000X is that you have the technical ability to crossband to pretty much any other band, 160 meters to 23 cm (minus 1.25 meters and 33 cm).

You are IDing on the output side by your voice, assuming you are always close enough to maintain positive control and contact with the crossband. To ID on the local side (UHF) I use an Arduino based timer and CW ID, no one but me, or people within the range of my UHF side, hear the ID. If you are not close enough to maintain positive control of the crossband you should ID both sides.

I put the UHF side into a very small antenna, such as a compact rubber duck or sometimes even a leaky dummy load, to keep the UHF coverage short, easily done as each of the radios I do this with have a separate UHF antenna port (except the FT8900R). An antenna switch takes the UHF either to the “big” external antenna, or to the “little” inside antenna for remote use. Your V71 has a single antenna jack for both bands, but you could use a duplexer (such as the Diamond MX72) to break out the UHF separate. A pair of antenna switches could be used to select either “normal” (both bands to external antenna), or “crossband” (2 M to big antenna, 70 cm to little antenna). I do something like this on my FT8900R installation. The other advantage of doing this (small antenna on local side) is that it reduces the possibility of someone capturing your crossband and causing issues.

With this last in mind do use some kind of CTCSS on the local side to reduce the possibility of accidental crossband capture.

How practical is all of this? Very practical. The delay through the radios is basically undetectable. You do have to break the squelch and also wait for everything to drop, but that can be almost undetectable if done right.

I do not run my corssbands at maximum power output, remember only the power required to make and maintain contact. Since the radios are not maxed out I have never had a duty cycle issue. But, you might also turn on the time out timer function (I think the V71 has one) in case someone captures the crossband from either side and keeps it keyed down.

T!

 

[KR7CQ]

I don’t have the TM-V71 but I do exactly what you are describing all the time on my TM-742A, my FT8900R, or my TS2000X (in fact, the TS2kX is in the house for only this purpose). It is very useful. I also do it from my vehicle mounted TS2000X when I am mobile, for example when I park someplace and hike the area. The nice thing about the TS2000X is that you have the technical ability to crossband to pretty much any other band, 160 meters to 23 cm (minus 1.25 meters and 33 cm).

You are IDing on the output side by your voice, assuming you are always close enough to maintain positive control and contact with the crossband. To ID on the local side (UHF) I use an Arduino based timer and CW ID, no one but me, or people within the range of my UHF side, hear the ID. If you are not close enough to maintain positive control of the crossband you should ID both sides.

I put the UHF side into a very small antenna, such as a compact rubber duck or sometimes even a leaky dummy load, to keep the UHF coverage short, easily done as each of the radios I do this with have a separate UHF antenna port (except the FT8900R). An antenna switch takes the UHF either to the “big” external antenna, or to the “little” inside antenna for remote use. Your V71 has a single antenna jack for both bands, but you could use a duplexer (such as the Diamond MX72) to break out the UHF separate. A pair of antenna switches could be used to select either “normal” (both bands to external antenna), or “crossband” (2 M to big antenna, 70 cm to little antenna). I do something like this on my FT8900R installation. The other advantage of doing this (small antenna on local side) is that it reduces the possibility of someone capturing your crossband and causing issues.

With this last in mind do use some kind of CTCSS on the local side to reduce the possibility of accidental crossband capture.

How practical is all of this? Very practical. The delay through the radios is basically undetectable. You do have to break the squelch and also wait for everything to drop, but that can be almost undetectable if done right.

I do not run my corssbands at maximum power output, remember only the power required to make and maintain contact. Since the radios are not maxed out I have never had a duty cycle issue. But, you might also turn on the time out timer function (I think the V71 has one) in case someone captures the crossband from either side and keeps it keyed down.

T!

Thanks, that's an impressive setup that I would like to strive for with time. For now you give some useful suggestions that I will make use of I'm sure. And I am a big fan of minimum power. Not only is it the right thing to do, I believe it has to prolong the life of most radios to some extent.

 

[rapidcharger]

What are the downsides from a practical standpoint?

Downsides...
You have to wait for the carrier to drop completely before you can transmit. Very annoying on repeaters with long hang times.

You have to ID obviously. The v-71 is a great radio, I have two of them and x-band with it daily. The CWIDer that is built in SUUUUCCCCCKKKKKSSSSSSSSSSSS.
Why does it suck?
It sucks because it tx on both sides. And it doesn't wait for a clear channel. It just transmits whenever. It will TX the ID whether there is activity or not so it will ping pong the repeater. And it's a very loud tone and it's very slow. It will annoy everyone.

You asked about cooling. Cooling is a very important consideration. If the radio is getting hot, you may want to supplement the cooling with an additional fan. This time of year you can find those little clip on fans very inexpensive. I know some people like the little muffin fans but I like the clip fans. That's just me.

You asked about a lag. The delay from from when you transmit until the repeater picks you up can vary but the v-71 itself doesn't add much of a delay. As a practice, I'd give it a second and a half to two seconds before speaking.


If you want to eliminate all the , here's what you can do.
The v-71 will do what is called Locked Band Repeat.
What this does is it only repeats you one way. It transmits out on the repeater but it does not transmit the repeater on the other band. When used with a dual band radio, you set the channel up so the radio is listening on the repeater's output and transmitting on your uplink to the v-71. ...
This solves the needing for the carrier to drop completly. This also solves the needing to ID on another frequency because it's not transmitting on another frequency. It also solves the cooling because it's only TX when you are TX instead of TX when everyone on the repeater TX. If you don't have a dual band radio you can use another radio. That's what I do to listen to the repeater's output. If you're not in range to listen to the repeater with a rubber duck then you've got a problem.

I really wish Kenwood would release a firmware update that would fix their useless CWid.

 

[N4KVE]

What this does is it only repeats you one way. It transmits out on the repeater but it does not transmit the repeater on the other band.

This is the way to go. You don't have to wait for the repeater to drop to get in, & it prevents the radio from melting. Icom, & Yaesu don't have this option, but if you program the freq correctly, you can trick them to do the same thing. We called it one way repeat.

 

[KR7CQ]

The v-71 will do what is called Locked Band Repeat.
What this does is it only repeats you one way. It transmits out on the repeater but it does not transmit the repeater on the other band. When used with a dual band radio, you set the channel up so the radio is listening on the repeater's output and transmitting on your uplink to the v-71.

Thanks for that very good summary, I learned a lot. Now a question on the portion I am quoting here:

Are you talking about the HT needing to be dual watch / dual tuner, or will a regular dual band like my FT-60R work? If it is the standard dual band, are you talking about essentially setting up a memory channel with a VHF RX frequency that has a positive transmit offset of like 300 MHz? I wasn't aware an offset could be that great, but maybe I am misunderstanding.

 

[nd5y]

Most current dual band radios allow you to program memories with separate transmit and receive frequencies without using an offset.

 

[KR7CQ]

Most current dual band radios allow you to program memories with separate transmit and receive frequencies without using an offset.

I just checked my FT-60R software and sure enough the offset is adjusted only but the shift entry, and there is not a second frequency field. I tried playing with offsets but 100 MHz is the limit.

Seems my fave HT is not going to work....

 

[nd5y]

That is weird. Check the manual. You might have to do it manually. I find it hard to believe the FT-60R doesn't do that. I used to have an FT-50R and VX-6R and I know they had odd split capability. On the VX-6R I could even make it receive on 10m and transmit on 440.

 

[nd5y]

Page 28 of the FT-60R manual shows you how to store odd splits.

 

[KR7CQ]

Page 28 of the FT-60R manual shows you how to store odd splits.

Good catch, I had missed that.

After thinking about this more, the plan of different TX and RX on the HT would only really only work with a repeater or simplex stations that aren't too far away. I don't think this plan will work out well with simplex for me, where I wouldn't hear many stations. Looks like the only real way is to have the base repeat what it hears back to the HT on UHF, which must really heat up the unit, but I guess that's why they have cooling fans.

On a related note....I saw a youtube video of someone doing the cross band repeat with an "open" yaesu mobile rig and a FRS radio but I can't find it now, though I know that is wrong and would seem very likely to attract attention / get someone in trouble and maybe cost them their license.

 

[KR7CQ]

OK, I was brainstorming for a "workaround" for doing this on distant simplex operations, and thought of one solution (though it is admittedly clumsy).

Keep your "crossband" memory in your HT, and then one the memory spot right below or above that one, put in the VHF frequency that the base radio is listening for to repeat. Once every ten minutes and at the end of transmissions, you could switch over a memory, ID on the VHF frequency, and this would then repeat your call sign over the UHF transmission your base is putting out, and if you used super low power you shouldn't interfere with anyone unless another station is super close. An even more nerdy solution would be to keep a second radio nearby with the VHF frequency already in it, with a stubby (negative gain) antenna, set to the lowest power to do the same with, and that would be almost sure to cause zero interference. The distance you can receive a signal from a HT on low power with a stubby antenna shouldn't be much more than a block or two based on what I have seen from FRS radios. And if I want to go this route, I can turn off the CW ID feature completely with the Kenwood I believe.

Would this be OK so long as you were not interfering with anyone via your handheld operation?

 

[rapidcharger]

Are you talking about the HT needing to be dual watch / dual tuner, or will a regular dual band like my FT-60R work? If it is the standard dual band, are you talking about essentially setting up a memory channel with a VHF RX frequency that has a positive transmit offset of like 300 MHz? I wasn't aware an offset could be that great, but maybe I am misunderstanding.

I'm not familiar with the ft60 but I would be surprised if you couldn't do it. (program a uhf freq for tx and vhf for rx)
If not, can you set up a separate zone or separate scan list and just program your uplink in ch1 and the repeaters output on ch2 and just hit scan when you're wanting to use it?
That way you can receive the active channel but remain on your simplex freq for transmit.

Like I said, I use two separate radios. I use a portable with rubber duck inside the house to receive (a repeater that is literally 40 miles away) and another portable just to TX with. If you can't even hear the repeater with a duckie, chances are you're not putting a real good signal into it.

Good catch, I had missed that.

After thinking about this more, the plan of different TX and RX on the HT would only really only work with a repeater or simplex stations that aren't too far away. I don't think this plan will work out well with simplex for me, where I wouldn't hear many stations. Looks like the only real way is to have the base repeat what it hears back to the HT on UHF,

For simplex, using the built in CWID would be less objectionable. (if it doesn't drive you nuts hearing it every 10 mins)

 

[fineshot1]

Some of the most interesting ham radio in my area, is on 2 meter simplex, and I am an active person who is moving around a lot when at home. Because of this, I am considering using 70 cm between my FT-60R and a Kenwood TM-V71A doing crossband to communicate with other stations on a popular 2 meter simplex frequency. This would allow me to work in my shop or the yard, or be anywhere in my house, while having the power, range, and reception of my base station.

I would run minimum power on UHF both directions, though I know that a high gain antenna 35 feet up on my mast is going to have serious reach anyway. Because of this I know that I will need to use the CW ID feature that sends regular IDs on both the UHF simplex frequency (from the base unit), and on the 2 meter simplex frequency, so that people are not hearing a bunch of guys talking to one guy who never ID's if they are monitoring UHF where my little HT signal can't reach them but the base can (IMO very likely to occur in Phoenix). My HT wouldn't ever be more than 75' from the base.

Assuming that this would be fully legal (correct me if I am missing anything there), my questions:

What are the downsides from a practical standpoint? Is there enough lag time waiting for radios that transmissions are delayed too much for efficient conversation on simplex where people typically respond very quickly after the other station is done with his TX (as opposed to repeater work)? Would the CW ID be annoying to people doing round tables (who don't have much dead air), by way of ID'ing over people every ten minutes, or is it a low enough audio level that it would likely be tolerable? Keep in mind that while the operators on this frequency obey the law, they are very casual and informal for the most part. Would long-time hams who are on the casual side likely find the CW ID annoying? Will this setup lead to an early death of the radio with such a hefty duty cycle and with long conversations? Are there other downsides I'm missing?

Actually with simplex on each end it is referred to as cross band link(not repeat).
I used to do this many times years ago when passing on check point info at various
events like 5K runs. I parked my car at the 1/2 point location and used that to be able to
communicate with all check points. With cross band link no need to hook up an ID device
as long as you periodicly simply voice your ID at about 10 or 15 minute intervals and a
special note of caution: NEVER Leave your cross band link or repeat equipment unattended
as leaving that online without others knowing what is happening can cause all kinds of havoc
and undesired interference. As the control operator of your equipment you must be in control
at all times. My Icom 900A was one of the first mobiles that offered cross band link back in
1987 and i used it many times with caution.

 

[robertmac]

Don't even think about doing cross band with FRS. Or any out of band using an amateur radio.