Posts Tagged ‘Mobile’
I’ve been interested in the idea of a microphone-centric radio and wrote about it here: How About a Mic-Centric Mobile Transceiver? Shortly thereafter, I discovered that QYT has introduced a VHF/UHF ham rig that has the display and controls in the microphone (Model KT-WP12).
You may want to watch the video by Tech Minds, which does a good job of introducing the radio.
I was very keen on trying this radio out, so I purchased one, paying about $110.
On the Bench
First, I did some bench tests to check the basic performance of the radio. The receiver sensitivity, transmit frequency and FM deviation all looked very good. The one specification that was disappointing was the RF power output. On the 2m band, the output power was 20.6 W, while the 70cm band was 15 W. The specification for the radio is 25 W. The power was measured using an HP 8920A RF Communications Test
I’ve noticed this on other radios from Chinese manufacturers: the basic specs of the radio check out, except the RF power level is low.
As you might expect, cramming all of the controls into the microphone is a challenging user interface design. I spend quite a bit of time playing with the radio at home before actually using it on the air. Overall, I found the user interface to be acceptable, but several areas that should be improved.
QYT relies on the menu system to provide control of many of the settings. This is similar to the various Chinese handhelds where you push the MENU button to access the menus, followed by UP/DOWN to sequence through the menus, followed by MENU to access the specific setting. Then the UP/DOWN buttons choose the value of the setting and another push on MENU to accept it. The volume control setting is buried in this menu system, which seems like a poor choice. Fortunately, Mick/M0VMK pointed out that the volume can also be set by enabling the monitor feature (big button on the top of the mic) and hitting UP/DOWN.
This design depends too much on the menu system. A few user-defined buttons would be a real help. This radio could benefit from a serious redesign using User-Centered Design.
This radio has one receiver but allows for three independent frequencies to be displayed simultaneously. There is a scanning mode that tries to emulate a multi-receiver radio. This too is all too common with the Chinese radios…somehow they have it in their heads that this adds value for the user. My experience is that it mostly confuses the user. Most users would be better served with a single frequency display, supplemented with dual-watch and scanning capability.
You probably won’t be surprised that the user manual is terrible, also common with Chinese manufacturers, but this one is particularly bad. Same with the programming software…it mostly works (I had a few crashes) but it is poorly written.
On The Air (SOTA)
I was very interested in trying out this radio for Summits On The Air (SOTA) use. The idea is that the radio can be stuffed into a fanny pack, with the microphone, speaker, display, and controls in your hand.
The basic concept of holding everything in the palm of my hand worked out quite well. The display was visible in bright sunlight, the speaker audio was clear, and the microphone worked great. I made a number of SOTA contacts and received good signal reports. I held the microphone in one hand and pointed the 3-element Yagi antenna with the other hand. (Joyce/K0JJW assisted with logging and we took turns working the SOTA chasers.)
As soon as I fired up the radio, I heard interference on the 2m band, not very strong but noticable. It sounded like it was coming from an FM broadcast station. Pointing the Yagi antenna in the direction of the FM station on the adjacent mountain seemed to confirm the source. I did not hear any interference on the 70cm band. I’ve operated from this SOTA summit before and have not noticed any interference with other equipment, including Yaesu handhelds. Also, I switched to my Yaesu FT-90 and the broadcast station was not heard. As various people have suspected, this indicates that the receiver in the QYT is not very robust in terms of rejecting off-channel signals. Of course, this is an anecdotal report, not based on bench measurements.
I also encountered an anomaly where after my transmission, the radio did not revert back to receive quickly. There was a few seconds where no audio was coming out of the transceiver. This caused me to miss a few responses to my CQ call. This issue requires some additional investigation. It may have just been operator error on my part. However, I suspect that the radio was probably locking onto another frequency but I am not sure (see previous comments about the three frequency scanning mode). So file this issue under “stay tuned for more information.”
Note that I did not use the radio very much on repeaters, focusing on SOTA simplex operating with no transmit offset or CTCSS.
On the positive side, I really like the microphone-centric approach that this radio uses. The user interface can be improved but it is good enough.
The two big limitations of this radio are 1) low RF power output and 2) weak off-channel receiver performance. Now you might say that the RF power is not off by that much but my interest is having a SOTA radio that greatly exceeds the power of a typical 5 W handheld. On the 70 cm band, this radio only put out 15 W, so only 4.7 dB better than a handheld. The poor receiver performance will tend be an issue on summits that have radio installations nearby. In some cases, this can completely prevent a VHF SOTA activation.
I will probably use this radio again for SOTA activations but I’ll be bringing along a backup rig, just in case.
Most automobiles don’t provide a lot of room for mounting ham radio transceivers. (Obviously, their design priorities are wrong!) Because of this, many ham transceivers have removable control panels that can be mounted on the dashboard and the main radio is installed somewhere else, such as under a seat.
Midland radio is doing some interesting things with micro-sized radios for the General Mobile Radio Service (GMRS). The MXT275 MicroMobile® Two-Way Radio puts all of the radio controls and the display in the handheld microphone.
This radio reminded me of an old Yaesu radio, the FT-8500, which had almost all of the controls crammed onto the microphone. (Someone named the microphone “Mr. Potatohead” which seems appropriate, but I did not name it.) This radio had the display on the radio body, which seems like a limitation. At any rate, this rig was not very popular. I do not know anyone that owned one.
So the FT-8500 was not a big hit but maybe it is time for another go at a microphone-centric transceiver. I am thinking a basic 2m/70 cm FM radio could use this approach to ease the mobile installation challenge.
Simplicity in Design
You may be thinking that a GMRS radio is fundamentally simpler than a typical VHF/UHF ham transceiver. This is true…a typical GMRS radio has 22 channels that might have options such as CTCSS tones and repeater offset. A typical ham transceiver has more frequencies, more features, and lots of settings required.
However, if you consider the typical FM transceiver setup and usage, most people set up the memories for the repeater and simplex channels they use, usually via programming software. After that, operating the radio is 99% just selecting the desired memory channel. This kind of usage lends itself to having a simpler set of controls that can be incorporated into the microphone. This approach will require a good understanding of user needs and some careful design work to create a radio that works well.
This type of radio design will probably not work for everyone. There will be hams that want every feature available all of the time. That’s just fine. However, the microphone-centric approach may be a good fit for installation in the “other car” that doesn’t get used quite so much. Or in the case where a family member objects to having a Real Radio cluttering up the dashboard.
Using this type of radio will be a lot like using a handheld transceiver, with the addition of a microphone cable, but no batteries or antenna cable drooping down. The Midland radio has the speaker in the radio unit but it may be better to put it in the microphone (with the option of plugging in an external speaker.)
I think this idea would well for some number of mobile radio installations. What do you think?
73 Bob K0NR
When on a road trip, I usually monitor the 2m FM calling frequency, 146.52 MHz. For the most part, that frequency is pretty quiet but sometimes a fellow traveler, camper, SOTA activator or random ham shows up on frequency. I don’t usually bother with tuning into local repeaters as that requires frequent adjustment of the radio while cruising down the highway.
Our RV has an Icom IC-2730A transceiver that covers the 2m and 70 cm bands. This radio has two receivers, so one receiver is set to 146.52 and other one is set to “something else.” Sometimes, I’ll go ahead and put one of the local repeaters in the other receiver, especially if we are going to hang out in one location for a while.
When driving near coastal areas, I often put the second receiver on the VHF Marine Channel 16 (156.80 MHz). This is the International Hailing and Distress Frequency for marine radio. You will hear boats calling each other on this channel, then switching to another working channel. It is also common to hear the U.S. Coast Guard come on the air with an announcement. (The USCG may say switch to Channel 22 to hear the announcement.)
Some other useful marine frequencies:
Channel 22 157.100 MHz Coast Guard Liason Channel
Channel 68 156.425 MHz Non-Commercial Working Channel
The complete list of VHF Marine frequencies are available here:
Just another frequency to listen to when on the road.
73 Bob K0NR
Joyce/K0JJW and I did another activation of Mt Herman (W0C/FR-063) today. This is a repeat summit for us this year but we were looking for an easy hike not too far from home.
As usual, we were just using the VHF/UHF bands for the activation. My favorite rig for this type of SOTA activation is a Yaesu FT-90, a very compact mobile transceiver (4 x 1.2 x 5.4 inches) that is no longer manufactured. It has a unique heatsink with an integral fan that can handle the heat from the 50-watt transmitter. We use a Bioenno 4.5 Ah LFP battery to supply the power for the radio.
I was trying to work Bob/W0BV about 65 miles away and we were not able to complete the contact. The distance is not too difficult but there are several mountain ranges in the way. Sometimes we can get the electromagnetic waves to sneak through, but not today. Hiking down the mountain, I was thinking about how we could have probably made the QSO on SSB or CW, instead of FM. I chose not to bring the all-mode transceiver (FT-817) along today, so that was not an option.
That is when the idea hit me. The FT-90 is the right form-factor and power level for VHF/UHF SOTA but it is limited to FM. Yaesu, if you are listening, here’s what I’d really like to see in a small mobile transceiver:
- FT-90 size radio, perhaps a little larger but not much
- 2m and 70 cm bands (include 1.25m if you’d like)
- At least 25 watts of output power, more would be better (say 50 watts)
- All mode capability (CW/SSB/FM/Digital), sure go ahead and toss C4FM in too.
- No internal battery…I’m going to have to use an external battery anyway to get enough battery capacity
At various times, I have had people ask “why don’t they put SSB in handheld radios?” They recognize that SSB has weak-signal advantages over FM, so they wish their handheld transceiver (HT) could do it. I say rather than shove more features into an HT, put it in an FT-90 size radio. It would be a much more usable solution.
Although I arrived at this radio concept thinking about SOTA, it would also be a great mobile rig for general use. The FT-90 was popular because it was very compact AND it had a removable faceplate that could be mounted almost anywhere. There really is no way to get VHF/UHF SSB into a vehicle other than those all-band radios like the FT-857 and the IC-7100. Oh, did I say FT-857? Sorry, that model has been discontinued. The satellite operators will love it, too, especially if it could work 2m/70cm crossband full-duplex.
So there you go, Yaesu (or Icom)…a fantastic product concept at no charge. I would be happy to beta test it for you.
That’s my idea for today. What do you think?
73 Bob K0NR
We recently completed a Technician License class that produced a herd of new ham radio licensees. This always leads to a discussion of what radio should I get? Often, this is centered on the idea of getting a handheld VHF/UHF radio to get started. That is a good first move. However, for many new hams it is worth looking ahead a bit to potential future purchases.
Handheld Transceiver (HT)
Let’s start with an HT. Even if your ham radio future is going to be on the high-frequency bands, an HT is a useful tool to have. After all, FM VHF is the Utility Mode for ham radio. Many new hams opt for an inexpensive Chinese radio such as the Baofeng UV-5R. Recently, I’ve been steering them toward the slightly more expensive Yaesu FT-4XR (around $70).
It is a significantly better radio than the UV-5R but still affordable. Some new hams decide to spend more on an HT, which is also a good option. There are many radios to choose from in the $150 to $350 range.
For hams just interested in local (perhaps emergency) communications, this might be the only radio they get. If it meets your needs, that’s just fine.
FM VHF/UHF Base Station
Another option to consider is to set up a more capable station at your home, focused on FM VHF/UHF operating. This is probably going to be a dual-band radio that covers 2 meters and 70 centimeters, FM only. One way to do this is to use a mobile transceiver powered by a DC power supply and connected to an external antenna on the roof.
With higher power (50W typical) and a good antenna mounted in a high location, this type of station has better range than an HT. See A VHF FM Station at Home and Considering a VHF/UHF Antenna For Your Home. This could be your first radio but why not have an HT in your toolkit?
The All-Band Base Station
Many new hams have their eyes on working distant stations via the high-frequency bands. For many people, this is what ham radio is all about. (Honestly, you’re going to need your General license to really participate on these bands.)
The equipment manufacturers have developed the Do Everything Transceiver that covers 160m though 70 centimeters in one box. (Well, they do leave out the 1.25m band which is lightly used in North America.) The leader in this category is arguably the Yaesu FT-991A. This type of rig has the advantage of providing all modes on all bands, including SSB on 2 m and 70 cm. While most VHF/UHF activity is FM, SSB (and CW) can be a lot of fun.
Setting up operations on multiple bands will require some additional antennas. This can be a deep topic so take a look at this introductory article to understand it better: Antennas…How Many Do I Need?
Two-Radio Base Station
Another approach that many hams adopt is to build their home station around two radios: a 2m/70cm radio to cover local communications and a high frequency (HF) radio for the lower bands.
The 2m/70cm radio is the same idea as the FM VHF/UHF Base Station mentioned previously. It is really handy to be able to leave this radio on your favorite 2m frequency while still having another radio available to operate HF. Compare this to the All Band Transceiver approach which can normally only receive one frequency at a time.
A very popular HF radio these days is the ICOM IC-7300. Like many HF rigs, it covers the HF bands of 160m through 10m AND tosses in the 6m band, too. Recall that 6 meters is actually a VHF band but the general trend is to include this band in HF rigs.
The Mobile Station
Another popular operating style is to have a transceiver in your vehicle. Because our society is so mobile, this approach can be very compelling. This might just be an HT that you take with you when mobile. The rubber duck antenna might be sufficient but an external (magnetic mount?) antenna can really improve your signal.
Many hams install a VHF/UHF FM transceiver in their car. This provides a more capable station (more power, better antenna) when mobile and it’s always there for use. Again, this will probably be a 2m / 70cm radio that operates only FM, the most common mobile ham station.
Some folks set up their mobile station to include HF operating. This is one way to sidestep HF antenna restrictions at home and it fits into our mobile society. There are Do Everything Transceivers that come in a mobile-type form factor. The Yaesu FT-857D is a popular mobile radio that covers HF, 6m, 2m and 70cm in one rig.
You can see that there are some paths that hams tend to follow in terms of equipment. What you decide to do is going to depend on your interests and budget. Of course, when you are first starting out you may not know what part of ham radio is going to be your favorite and your approach may evolve as you gain experience.
A good first, affordable step is getting an HT. This puts you in touch on the air with the local amateur radio community. It is clearly a VHF/UHF FM play which aligns well with your Technician operating privileges. You can choose to expand on this general direction by adding in an FM VHF/UHF Base Station, an All-Band Base Station, or a Mobile Station.
If you are interested in using the HF bands, then think about either the All-Band Base Station or the Two-Radio Base Station. Again, obtaining a General class (or Extra class) license is going to be important for HF.
I’ve tried to keep this discussion focused on newly licensed hams. As you gain experience, you’ll find all kinds of other operating activities that are available to you. Sometimes these can be supported by the equipment described above…sometimes you’ll need to purchase additional gear. I’ve mentioned specific radio models that I have experience with but there are many others to choose from. Take a look at the eham.net product reviews to see how well other people like a particular radio.
73 Bob K0NR
[My apologies. I fumble-fingered WordPress and published a draft version of this article that was incomplete. This is the corrected version. ]
Sometime during the 20th Century, I learned that fuses (or circuit breakers) are used in electrical circuits to prevent catastrophic failure. Fuses open in response to an electrical fault that causes excessive current to flow. The job of the fuse is to minimize the damage and keep things from catching on fire. When I started installing amateur transceivers into vehicles, I learned that you should connect wires directly to the car battery (or darn close) and you should fuse both the positive and negative power leads. I was surprised by the need for two fuses, but there are technical arguments for it. Besides, the transceiver manufacturers recommend it in their manuals. (See figure below.)
I am focusing this discussion on a typical 2m/70cm FM transceiver installation – that is what I have the most experience with and that is the most common ham mobile installation. Such a radio typically draws ~10 A on transmit, so the DC power is usually fused with something like a 15 A (or 20 A) fuse. Keep in mind that a 15 A fuse is not going to protect delicate circuitry but might stop more serious damage or fire.
Connect To The Battery?
Alan/K0BG has an excellent website that provides guidance on mobile radio installations. He points out that modern vehicles usually have an Electrical Load Detector (ELD) inserted into the negative lead of the battery, so that the vehicle control systems can monitor the state of the battery. It is important to connect your radio on the “other side” of the ELD, near where it connects to the vehicle chassis. Oh, and never use the existing vehicle wiring to power your radio (especially not the 12 V accessory plug).
One Fuse or Two Controversy
Recently, I became aware of controversy with regard to proper fusing. Some people are questioning the practice of fusing both DC power leads, while others are vigorously defending it.
For example, there is a lively eham.net discussion here. Ed/W1RFI provides some useful insight on the ARRL forum. Alan/K0BG covers the topic of DC power on his wiring and grounding page. Tom/W8JI argues for the one fuse approach on his website.
What Do The Manufacturers Say?
Generally, you should follow the advice of the manufacturer on any equipment installation, so I took a look at a few owner’s manuals. Most (or all?) of the manuals for the amateur gear show the two fuse method. See the ICOM example below. (Note that they don’t show the presence of the ELD.)
I also took a look at some commercial land mobile radio manuals. Motorola shows the single fuse approach.
Hytera also shows a single fuse in its land mobile manuals.
ICOM makes both amateur and commercial land mobile gear, so I wondered what they recommend for their land mobile product line. Ha, funny thing, they show two fuses, with a comment that says, “Depending on version, the fuse holder may not be attached to the black cable.” Well, isn’t that special?
So is the two-fuse thing some kind of ancient amateur radio practice and the land mobile industry has gone a different path? Sometimes industries adopt “standard” approaches and then forget why with time.
Some Circuit Analysis
After reading through all of the arguments, I tried to distill them down to their essence. I created a wiring diagram that may help explain the concepts. Or maybe not. An automobile is a complex electrical and electronic system, so any practical diagram risks oversimplifying the situation. But here’s my best shot at it.
The center of the diagram shows the body/chassis of the vehicle which is connected to the negative lead of the battery, through the ELD. The transceiver is directly connected to the + terminal of the battery (via Fuse 1) and the chassis side of the ELD (via Fuse 2). The engine starter is connected to the battery with heavy cables and is also connected to the body/chassis. While there are a large number of other electrical devices in a modern vehicle, only one is shown here as an example (with a switch and fuse).
The circuit shows the antenna connected to the radio with a coaxial cable. The shield of that cable is almost always grounded to the vehicle chassis at the antenna. (Magnetic mount antennas are one exception and I am sure there are others.) I can say that every mobile installation I’ve ever done had the coaxial cable connected to the chassis. This is an important point because it provides a chassis connection for the transceiver at point C (whether you wanted it or not). There may be other ways that a transceiver is connected to chassis (point B), including the mounting bracket, external speaker, microphone or other accessories.
Arguments For and Against
The argument for fusing the negative lead is to protect against return current from other devices that find its way back to the battery through the transceiver’s negative power lead. For example, the starter could have a fault in its negative cable, causing the current to flow through the chassis to the transceiver and back to the battery. The starter current can be hundreds of amperes which would likely overload the radio wire which is sized for 15 amperes. The fuse will open and protect the negative lead (and maybe the radio, to some extent).
The argument against fusing the negative lead is that if the fuse opens up, it could cause problems. Suppose Fuse 2 opens up due to some transient condition. If the transceiver is completely isolated, Fuse 2 would remove power from the transceiver. However, the return path at the antenna coax (point C) will most likely allow the radio to continue functioning using the coax as the negative return. Typically, this is RG-58 or similar cable, which is not intended to carry significant DC current and may fry under the load. If the current is coming from a fault in the starter wiring (big current), this is going to be a bad day for your mobile.
I think both arguments have merit but choosing one fuse or two requires estimating which problem is most likely and judging the overall impact of the fault. The negative lead fuse can do only one thing well: protect the negative lead. It might provide some protection to the transceiver but there are a lot of sensitive circuits inside the radio that will get destroyed with 15 A flowing. Again, the connection at point C means that the radio will be connected to chassis and current can flow.
If Fuse 2 is eliminated it allows for the flow of high currents through the negative lead of the transceiver. This is not desirable but is it better or worse than the current flowing through the coax shield? Probably better. If a high current device (the starter) has a wiring failure that dumps large currents into the chassis, it may find a number of return paths. Lots of current is going to flow somewhere and potentially cause damage, with or without a negative lead fuse.
I will note that bonding the transceiver to the vehicle chassis has some benefit (point B in the diagram). You may or may not have this connection depending on how you mounted the radio. This electrical connection can shunt any currents away from the coaxial cable, hopefully doing less damage that way.
What am I going to do? My future mobile installations will have only one fuse in the positive lead. I’ll also bond the radio body to the vehicle chassis, with a hefty, low-resistance connection.
My existing mobile installations all have two fuses. I won’t be changing them out because the risk of inducing a problem with the negative lead fuse is rather low. I don’t see the negative lead fuse as a big risk. If you choose to follow the amateur radio manufacturer’s two fuse recommendation, I understand.
The amateur radio equipment manufacturers need to give this issue a fresh look. At a minimum, the presence of ELD’s needs to be addressed and the common recommendation of wiring directly to the battery is obsolete. But the one-fuse-or-two issue should also get a careful look by the manufacturer’s engineering teams.
That’s my analysis. What do you think?
(Runs and ducks for cover.)
Note: This article is my technical opinion but my attorney says to tell you that you are responsible if you destroy your vehicle while wiring up your transceiver.