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Recommend a dual/band with easy extended transmit mod

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Reflex439

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#1
I’m hoping someone can help me with a specific recommendation on a dual band 2m/70cm, with extended receive, and an easy modification to extend the TX range. I would prefer the extended TX mod to be easily switched on/off if possible.

I know the Kenwood V71A could be modified as such due to its easy wire cut mod, so adding a switch would be a piece of cake to enable and disable the mod. However, it requires a radio reset which requires re-programming the radio to go between the normal and extended TX. Not that big of deal since I can easily re-load all programming via software, but would rather not have to if possible.

For my use, I only need the extended transmit for limited periods, and wish to run the radio normally most of the time. Hence the reason I like the idea of adding a switch to the cut wire, rather than just cutting it and running it extended all the time.

I know this is a very narrow request. But does anyone know of a dual band that can be easily switched in and out of extended transmit like the V71A, but not require a reload of the programming? I’m guessing all will require a reset, but asking just in case.

An alternative, would be a dual band that is easily modified permanently, but the software can disable transmit on a channel by channel basis. That's another option. The Kenwood doesn't have an option for disabling TX on a channel by channel basis I've been told.

Thanks in advance
 

W9BU

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#2
I kinda doubt that you are going to find an amateur radio with an easily switchable out of band transmit mod. Amateur radio transceivers are marketed for amateur radio purposes and are not intended to be used for transmitting in other radio services. Depending on what country you are in, doing so is potentially a communications rule violation.

You would be better off, I think, to use a commercial land mobile radio that can be programmed for amateur radio frequencies. For example, a Kenwood TK-790/890 pair with the dual-band single-head option would give you a rock solid radio that will work on both amateur and LMR frequencies.
 

jbantennaman

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#3
Most all new transceivers will do what you ask, if you don't ask it to do it on the same antenna.

To put in my own two cents - what you are asking is against the rules per the Part 97 and 95.
The radio needs to be either or and not both.

I have a friend that has an old Icom mobile dual band that did not have any limits.
I suggested that he leave police frequencies out - due to the fact that it would be easy to forget and try to transmit on those frequencies. As with most people - he didn't listen to me.
There will come a day when he will transmit and someone will hear him and they will come looking for him. He is employed by the county jail. The cops knows his voice. It's just a matter of time before he gets caught.

Unlike amateur radio - where there is little rules and even less enforcement, with public service radio equipment, it was mandated a number of years ago to be narrow banded.
The wide band equipment sticks out now - like a sore thumb!
And the scanner people can hear the difference right off the bat - because his signal is twice as loud as the police on analog. A friend of mine spent months narrow banding all of the fire and ambulance equipment in the area before the end of the year - and the splatter box ICOM stuff is not my favorite brand. Most of the older Yaesu stuff will also do expanded transmit and receive by removing one resistor.
 
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#4
I’m hoping someone can help me with a specific recommendation on a dual band 2m/70cm, with extended receive, and an easy modification to extend the TX range. I would prefer the extended TX mod to be easily switched on/off if possible.
Depending on what country you are in, there may be some legality issues with what you want to do.

What, specifically, are you looking to do? What radio services/frequencies are you looking to use outside the amateur radio bands?

Since you specifically asked for a "dual band 2m/70cm" I'm going to go out on a limb and say that you are an amateur radio operator.
The issue is that a purely amateur radio is not type accepted for use anywhere other than the amateur radio bands.
Doing modifications, even temporary ones, would result in using the radio on the commercial/public safety/GMRS frequencies in violation of the FCC rules.

Might not be a concern for you, and that's your choice. Where it can be an issue is that if you are operating under someone else's Part 90 license, you are potentially putting them and their license at risk. Make sure you know what you are getting into before proceeding with this.

However, there are options...

Using a commercial radio that is type accepted for the frequencies you want to use that are outside the amateur radio band is a good option. You can still use these radios for amateur radio use, however you loose the VFO and usually the front panel programmability.
You'd stay legal, if you were operating with the appropriate licenses, this way. Nice thing is, these commercial radios are often really good and in a lot of cases have better receivers that most amateur gear.

There are also a number of low buck Chinese radios that have hit the market. A few of them seem to have Part 90 FCC certification as well as some functions that make them useful for amateur radio. I don't use these radios, so I can't recommend a specific one, but it may be an option.

In the end, it's up to you. There are amateur radios that can be modified to do what you want, however most of them won't do the required narrow band FM, as stated above. Just be aware of the possible consequences.
Also, having the appropriate antennas is something you'll need to pay attention too. Most of the amateur/consumer grade antennas are tuned for the amateur radio bands only, and don't have the bandwidth needed to cover into the LMR/Part 90 frequencies. Using wide band antennas for this is going to work better.
 
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#5
Most Chinese dual-band radios cover 136-174MHz VHF and 400-480MHz UHF. Most (but not all) can be programmed so that individual channels are RX only. I'd suggest researching one of these, and programming the non-HAM channels RX-only, unless you have written permission to TX on the frequency.

If a handheld would work for you, you could get a Baofeng UV-5R for less than $30, and use CHIRP (free download) to program it.
 

Reflex439

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#6
Thanks for the feedback. Very helpful.

Handheld wouldn’t work for me. I need the extra power of a mobile, and will have a decent bank of 12V AGM batteries to power it. So I really need the reach of a mobile vs a handheld.

The mod isn’t for illegal use, and not part of someone else’s part 90 license, so I’m not really concerned with those legal issues.

I’m not really looking for an out of the box solution either, as making a radio easily switchable between normal and extended transmit is fairly easy. if the mod is as simple as cutting a jumper (i.e., Kenwood V71A), or adding/removing solder across a couple pads (many others), its trivial to wire in a small switch and mount that to the case somewhere. The problem is imost radios I’ve researched then want a reset after making the modification, requiring a reload of the programming. Thats the part I am trying to avoid and was hoping someone has been there/done that, and can add some advice.

Programming that would limit the channel to RX only could be the ticket. That way I can restrict the transmission avoiding an accidental transmission, but allowing a very simple and quick way to transmit when needed by changing that option. If it can be done at the radio head without needing a laptop and software, that might be the final solution I go with.

Thanks again for the sage advice.
 

Reflex439

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#8
Sure, here is what I am trying to do…

I am trying to find a way to do an extended modification on a dual band radio, but rather than have the extended transmit enabled all the time, find a way to enable or disable it fairly easily on the fly. The reason would be to guarantee there would be no accidental transmission on non-amateur frequencies, but still allow the radio to be easily configured to transmit on non-amateur frequencies as needed.

So whatever suggestions seem to fit that goal would be right on target. The programming of channels for RX only is a good one, and one I hadn’t thought of. Thats the type of info I am looking for.
 
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#9
Most radios have a hundred or more channel memories. Buy one that allows the programming of RX-only channels, then have one section of RX-only channels, and another section that allow TX, but are labeled differently. So instead of flipping a switch soldered into the motherboard and rebooting the radio (which wouldn't work anyway, because when you enable/disable the out-of-band mod, all channel settings usually get reset), you switch to channel 121 instead of 21 to enable TX. It's cleaner, won't require constantly reprogramming the radio, and isn't any less idiot-proof than having an out-of-band enable switch.
 

jbantennaman

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#10
Reflex is talking but isn't saying much.
What Reflex fails to realize is that there is no FREE BAND frequencies on UHF or VHF.
Everything alloted fits in some sort of Part Type acceptance.
The rules for FRS and GMRS is pretty strict for persons not licensed, and as we have tried to explain - it still needs to meet the rules half way.
The Unlicensed MURS and FRS limits the amount of power you can use for a reason - because there is always some CB Rambo that wants to be a hero - with a big signal, that will cause problems for other users trying to share the bandwidth.

It all basically goes back to what happened in the 1970's with CB radio.
The 1/2 watt / 1 watt rule and fixed antenna limits the range of the bubble pack unit, allowing the user to share the frequencies with other users. That is why no license is required for those types of radios.

There is a lot of Preppers out there that thinks that in a disaster or emergency - no one is going to be listening to these frequencies or is going to enforce the rules.
It is very common for those people to combine two cheap handhelds, attach them to a base station antenna, affix them to a 70' telephone pole, or put up an illegal antenna on a PLMRS tower with the radios in a cooler at the base of the tower.

Even if the radios are discovered, how much investment are they out?
A couple of $30 Beofungs...
 
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#11
JB is right, Reflex hasn't addressed WHY he wants to do this.

Does he occasionally moonlight for a VFD, and thus occasionally have a plausible excuse for TXing on the VFD's frequency?

Does he work pert time for a business that would require him to occasionally TX on the business frequency?

Or does he want to be able to "borrow" unused frequencies in the event of a zombie apocalypse or TEOTWAWKI?

The "why" drives the "what", and also dictates the "whether".
 

bill4long

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#12
I’m hoping someone can help me with a specific recommendation on a dual band 2m/70cm, with extended receive, and an easy modification to extend the TX range. I would prefer the extended TX mod to be easily switched on/off if possible.
All of the chi-com radios (Baofeng, Wouxun, etc) can be easily extended via software.

Other radios (kenwoods, icom, yaesu, etc) are easily extendable by clipping a diode or two.

Why do you need to switch the capability on/off? It is not illegal to merely possess a radio that is unlocked. It is only illegal to transmit on such a radio unless you are licensed on the frequency, and the radio is type accepted for that frequency, for example, the MARS/CAPS frequencies which allow the usage of unlocked ham radios (assuming you have a license.)
 

Reflex439

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#13
bill4long, I think the Baofeng/Wouxun/etc also require a reset to extend the transmit, and was aware of those options. I was hoping clipping a wire/diode might get around that. I know on a Kenwood V71A and a few others I’ve checked I can clip a wire jumper, but found it also needed a reset. Doesn't really help. Same with removing or adding solder on pads, or removing a resistor. But that started me down the hardware mod path wondering if there were other radios with a hardware mod that didn’t require a reset. The more I look, the more I look I find a reset is probably going to be required whether its hardware or software.

The reason I want to be able to easily switch it on and off is to prevent an accidental transmission on unauthorized frequencies during normal use. Kind of like a safety on a firearm, you only turn it on when you are ready shoot. The rest of the time it’s there to prevent an accidental discharge ;) And secondly, it would prevent me from having to have two radios, one for normal use, and one for extended.

Appreciate the help.

Reflex is talking but isn't saying much, Reflex is talking but isn't saying much.
What Reflex fails to realize is that there is no FREE BAND frequencies…..
Reflex realizes far more than you assume. This has nothing to do with FreeBand, FRS, MURS, GMRS, CB, or apocalypse use. I am well versed in type acceptance, frequency allocation, licensing, Part 97, 90, 95, etc., whats legal and what’s not.

The ‘Why’ does drive the ‘What’, as well as the ‘Whether’, and then leads then to the ‘How’

I’ve already solved the Why, What, and the Whether, and all I need is the How. Hence, why I am here asking.

I think jonwienke has the best answer. Its probably the only way to have a clean solution to what I need. That’s IF, I can turn on/off the RX only option at the face of the radio via function keys, rather than having to download software from a computer. I’ll adjust my research toward that goal. Thanks.

If that doesn't work, then I'll get a second radio, make the mod, and only use that radio when I am going to transmit out of band. The Power switch becomes the enable/disable button! Pretty failsafe as far as accidental transmissions go.
 
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#14
Here is a possible solution, a part 90 radio that also does amateur. From the factory most of these radios have VFO operation for amateur frequencies and the part 90 frequencies are programmed via software. There is an option to make the radio wide open for field programming anywhere that can be reversed. The Anytone radios are also good performing and better than the Baofeng and Wouxun brands.

AT-5888UV | Chinese Dual Band Mobile Radio
prcguy
 
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#15
bill4long, I think the Baofeng/Wouxun/etc also require a reset to extend the transmit, and was aware of those options.
No, they come out of the box with the ability to transmit on any VHF or UHF frequency (136-174, 400-480MHz).

What you're originally asking for (an "extended transmit" switch) won't work. When you perform the mod, the radio usually resets, and wipes the channel memories. You then have to reprogram the radio.

The Baofeng, Anytone, TYT, Wouxun, and other similar radios have enough memories that you can program RX-only and TX-enabled versions of frequencies you normally don't want to transmit on. Just make sure each preset is clearly labeled and separated. If you put "TX" in the channel label and use a +100 offset for the TX-enabled preset (e.g. channel 29 is RX-only, channel 129 is TX-enabled), you can easily switch but still have minimal chance of accidental TX.
 
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#16
The ‘Why’ does drive the ‘What’, as well as the ‘Whether’, and then leads then to the ‘How’

I’ve already solved the Why, What, and the Whether, and all I need is the How. Hence, why I am here asking.
I think that Reflex is a politician, because he has the 'Texas Two Step' down pat.
Could be why he has the why, what, and whether, but not the how:wink:
Larry
 

KR3LC

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#17
Most of my equipment is modded and to avoid transmitting on public safety or other frequencies outside of amateur service where this concerns me my solution is to program in an illegal offset. The radio errors when pressing TX.


Most all new transceivers will do what you ask, if you don't ask it to do it on the same antenna.

To put in my own two cents - what you are asking is against the rules per the Part 97 and 95.
The radio needs to be either or and not both.

I have a friend that has an old Icom mobile dual band that did not have any limits.
I suggested that he leave police frequencies out - due to the fact that it would be easy to forget and try to transmit on those frequencies. As with most people - he didn't listen to me.
There will come a day when he will transmit and someone will hear him and they will come looking for him. He is employed by the county jail. The cops knows his voice. It's just a matter of time before he gets caught.

Unlike amateur radio - where there is little rules and even less enforcement, with public service radio equipment, it was mandated a number of years ago to be narrow banded.
The wide band equipment sticks out now - like a sore thumb!
And the scanner people can hear the difference right off the bat - because his signal is twice as loud as the police on analog. A friend of mine spent months narrow banding all of the fire and ambulance equipment in the area before the end of the year - and the splatter box ICOM stuff is not my favorite brand. Most of the older Yaesu stuff will also do expanded transmit and receive by removing one resistor.
 

Reflex439

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#18
The offset idea is a good one KR3LC. That way if I am in memory mode, I am safe regarding out of band transmissions. Thats a good solution covering 90% of my operational modes, with the risk limited to the other 10% in VFO mode. I would suspect that each radio may have some differences in what they consider an illegal offset, so I’ll look into that. Thanks for the helpful ‘out of the box’ thinking!

Here is a possible solution, a part 90 radio that also does amateur. From the factory most of these radios have VFO operation for amateur frequencies and the part 90 frequencies are programmed via software. There is an option to make the radio wide open for field programming anywhere that can be reversed. The Anytone radios are also good performing and better than the Baofeng and Wouxun brands.
prcguy
I do like Anytone over the Baofeng and Wouxun radios. Nicely made and good performing. But if I understand you correctly, I think I need the reverse of what you stated, or am not completely understanding.

I would want the amateur bands to use the memory to store frequencies, shifts, offsets, tones, alpha, etc, as its the radios primary function. The out of band frequencies could be individually programmed via VFO on an as needed basis, and that would be fine. Rarely would it be transmitting off the amateur frequencies, so its definitely secondary to ease of operation on the amateur bands. I don’t need to store any of the out of band frequencies, although in some cases it might be helpful, but not a necessity. I just need the ability to quickly and easily program in freq, tones, offsets, etc, on the fly with only the radio buttons or menu functions.

The problem is when I mix amateur and LMR frequencies for casual monitoring or Public Service, Air, etc, there is a good probability that at some point I’m going accidentally transmit where I don’t intend. Having a dual receive and cross band capable radio with dual VFO/CTRL focus just adds to the issue. Although KR3LCs idea of adding an offset to any programmed frequency off the amateur band could potentially resolve the whole problem for me.

Being able to turn on and off extended transmit without having to reset/re-program is the holy grail. I didn’t think it would be a reality, but you never know until you ask which is the thrust of my initial post.

Could be why he has the why, what, and whether, but not the how:wink:
Larry
Or perhaps I just know that the How is the only pertinent discussion point if the why, what, and whether have already been resolved and no longer relevant. Further, How can be solved without ever knowing the Why, which I am also smart enough to know opens pandoras box for trolls, so Why even go there (pardon the cheap pun :)

Focusing on the how will save everyone valuable time none of us seem to have enough of these days :)

Wow, I do sound like a politician LOL
 
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#19
Just buy a Part 90 radio...

Part 90 radios are authorized for amateur use.

Your statement......."I can restrict the transmission avoiding an accidental transmission, but allowing a very simple and quick way to transmit when needed by changing that option."

Why would anyone want to transmit "out of band" if even for a second on a HAM radio?


Awhile back someone posted in here about being an police officer and either using or wanting to use a Beofeng on duty......go figure. :roll:
 
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WatnNY

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#20
You do NOT "clip a wire" to get extended TX capabilities on a Kenwood V71A.

Your best bet is to buy a commercial radio and program one bank for receive only, and another bank with the TX capabilities.

There. All those conversations and I just solved the whole problem for you.

Mike
 
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