HamGeek usDX 40/20/15 meter QRP radio

 Because I bought one so you do or don't have to.

More on Packet Radio

 Navigating packet radio can be very hard, especially if you're just starting out in the hobby. You may have questions like "What's the difference between APRS and packet?" or "Why can't I use X software for packet?" Heck you may even wonder how can you set up your own packet radio operation. Today, I hope that this blog post can put some of those wonder and questions to rest. So follow me as I delve into (hopefully) helping you get your start in the internet of amateur radio - packet radio!

Radioless ASL Node: Putting it ALL Together

Now that my Motorola is the candidate for a UHF APRS node, I am going to construct my AllStar node to function as a personal, radioless node. Stick around for the final build!

Attempting to Repair a Uniden PRO500D

I bought another CB off of eBay that was a heck of a steal at about $10 or $15 shipped. It's a late 80s/early 90s Uniden CB radio. It's very similar to the PRO510 and PRO520 line of modern-day radios. It's quite basic - no ANL, no PA...just volume, squelch, and 40 channels.

QYT KT-8900 Kaput???

 Back again with a 6 month review and update of my QYT KT-8900.

I have to say that I am thoroughly impressed with this radio, despite it not reaching the 25W promised output. I can still live with that though! I can easily access the repeater anywhere in town with a simple mag mount antenna. The microphone issue never really seemed to be an issue in the first place. However, the mic may have a different problem associated with it now that I've had it in my car for a bit.

The Main Issue

Here's what I think...

On cold days, when my car is not started, I can climb in and key up the radio. However, as the environment around me warms up, the microphone stops working. I can key the microphone which transmits a non-CTCSS carrier, but it never seems to transmit the CTCSS code. When I let the PTT up, it transmits the squelch tail properly on the repeater.

Now, it doesn't always work when it is cold, and the workaround is to twist and bend the mic wire every which way in order for it to transmit. I've narrowed down the problem to one of two places - the mic cable or the microphone itself. So I'm planning to order a different styled microphone in the hopes that it will solve the problem! I highly doubt it is within the radio circuitry but that isn't out of the question quite yet.

Here's what actually happened...

So we have two cheaply-made radios here - a Baofeng UV-5R and a QYT KT-8900. One has a very weak and insensitive receiver, meaning that every time I key up my QYT very close to the Baofeng (in this case, INSIDE of the car or a VERY large Faraday cage), I'm essentially overloading the Baofeng's receiver. The UV-5Rs do suffer from this design flaw and are known to have crappy receivers if overloaded. They just become so deaf they're useless. Due to the receiver sensitivity being quite finnicky, you just kind of get what you pay for. This is more so the problem - the UV-5R is so overloaded by the mobile radio that it doesn't even pick anything up, only the repeater's squelch tail. 

Problem solved - no mic needed here!!! Phew!

Again, ham radio problem-solving at its finest, ladies and gents!

How's it going?

Well, to be honest, the KT-8900 does the job just fine, even at around 10 watts! CHIRP just released another stable version a few days ago and it appears that I can finally customize the settings without a problem.

I've attached the radio via Velcro just below the steering wheel where it is out of sight from view. The Velcro does a much better job than Command strips at fastening, securing, and holding the radio. 

Again, my recommendations still stand. Turn down the power pot so you're only at around 10 watts on high power or replace the final transistor. The first is the easiest option by far, and only takes around 5 minutes. It is a very touchy adjustment so adjust in tiny increments.

So, after almost half a year, I'd still recommend this radio. 

Realistic TRC-412 Emergency CB

It's an emergency CB radio! How ingenious! Guess who bought one? ME!!!

A Month with the QYT KT-8900

 Well it's officially been a month or two since I first received the QYT KT-8900. As promised, I would like to do a one-month check-in on this rig!

QYT KT-8900: The UV-5R's Mobile Big Brother

I've decided to install a mobile-oriented radio in my brand-new-to-me vehicle. There are many on the market right now, but one caught my eye in particular:

This is the QYT KT-8900 VHF/UHF radio. It claims to run at 25W but let's be honest here, it will only run about 15, maybe even 10 watts. That's still not bad, considering that this is from - you guessed it - China. At just a little under $100, I decided to take the plunge and see how it would perform as a mobile rig.

First-Look Impressions

Initially, this radio had been riddled on YouTube, reviews, and forums with issues right off the bat. The worst of it was the final RF amplifier. The final is heavily overdriven in this application and normally, it would run at 6 or 7W max output. This works, however, these radios don't use heat sinks on the final, rather, they use a piece of "thermal foam" entrapped under a piece of brass. Despite having a fan on the rear, this is not enough to cool the final if the SWR happens to be mismatched. Some models don't even have a fan, so overheating is expected anyway. So, my first suggestion if you purchase this is to take the manufacturer's "heatsink" off, add a very minute dab of CPU compound and place an aluminum heatsink on top. Also, use a properly tuned 2m or 70cm antenna. Problem solved, heat dissipated, no SWR overload... for now...

Next, there have been complaints about this radio not being compatible with CHIRP. The supplied QYT software seems similar to CHIRP and it may do just fine with me. However, it is imperative that you install the PL2303 - this is the driver you need to program with the provided cable. If all else fails, it will program manually just like the UV-5R via the keypad. If you're on Mac or Linux, CHIRP will be your only software option.

UPDATE (10/22): It appears that CHIRP now works flawlessly with the radio I have. Previously, I could not edit any of the customized settings, such as the power-on message. This was due to an invalid BCD. In the 10-20 update, CHIRP appears to have resolved this problem and I can now adjust custom settings. Despite the model still being labeled "experimental driver," I think it's safe to say that CHIRP now can communicate with my radio without an issue.

Of course, if you'd rather, you can build your own using a <$5 CP2102 and a 3.5mm stereo (TRS) jack. The pinout is simple and building one is just as easy. The tip is TxD (RxD on CP2102), ring is RxD (TxD on CP2102), and sleeve is ground. If you find that it doesn't work, try swapping Tx and Rx pins. Some modules may be wired backwards. As an added protection against power cycling during programming, 10K resistors can be added between the serial pins and ground.

I've also heard that the included microphones with these have very poor audio quality and I have found a minimal amount of modifications to fix this. The solution, obviously, is to use a different microphone. I suggest using Kenwood's line of RJ-45 mics - this should solve the problem. For a better money saver, there is an SMD resistor (value 332, 3.3kOhm) that can be lifted from one pad or, as a better solution, removed completely and replaced with a 5K pot, as shown in this Facebook post here (click the photo for better resolution):

One other issue I've heard is that these don't work the best as mobiles and will pick up everything from vehicular EMI/RFI as well as pager systems if you town uses them. The obvious answer to this, in my experience and opinion, is to use as many ferrites as you can. Wrap the DC cable in a snap-on ferrite about 3 or 4 times and place a few on the antenna coax as well at the radio end. This should mitigate some issues, but your mileage may vary.

The issue of having only one 3.5mm jack appears to be resolved. It was previously mentioned on various forums and sites around the internet that this radio lacked an audio out jack. The rear one, at least on mine, is indeed an external speaker output which will mute the top speaker. The front is the programming jack. 

Lastly, if you need to replace the final for peace of mind, or if you experience a thermal burnout (aka, releasing the magic smoke demons), this page details the how-to. It's not entirely difficult and the part I'd replace it with would be this one at DigiKey. It is better suited for this radio (16W output vs only 6W output) than the claimed factory one and is well under $10. For now, I will put a modified heatsink on the factory chip with a dot of CPU paste as I mentioned above and turn down the middlemost potentiometer to achieve a maximum of 10W output, as seen in the screenshot below. This should save the final until I can replace it with the better one. And for reassurance, the Leixen brand radios of the same size also utilize this much power output.

Despite this, I purchased one just to see how bad (or even good...) these are. I do have high hopes, but we'll see if the product delivers. Have they improved quality control over the past 10 years or will it still scream "Made in China?" 

So here we go - my review.

My Thoughts

Instead of using a UV-5R as a mobile, why wouldn't I use a mobile-specific radio that is about the same size and can push out around 10 or even 20 watts? I think I will also hold on to my UV-5R as an HT and use the TK-705 (IF I EVER GET IT FIXED!!!) for APRS since it's pretty well scrapped. The final stage on it and APC stage are both completely useless at this point so I might have a few ideas to push some watts out.

Here's what I like about the 8900, according to the claims:

• Small profile - easy to affix anywhere in your car or truck. For extra security, you could even put it beneath a seat out of sight! It's literally as big as a slice or two of bread.
• Ease of use - If you started off with a Baofeng UV-5R, you'll have no issues moving to this as a mobile radio - they're the same thing and have the same menus and interfaces!
• Dual or Tri-band - If you use 220MHz or the 1.25m band, you'll be happy to know that this is also offered as a 2m/1.25m/70cm model, though 2m and 70cm is plenty active around my area.
• Cooling fan - After the final stage complaint, I'd say the company(ies) tried to fix the issue, but in any case, a cooling fan is a must. A simple modification can be found on the link to replace the final above.
• CTCSS, DCS, DTMF, etc. -compliant - you can't really do repeater work without this!
• Safe-for-car power draw - Rated at 4 to 5A max on transmit, some claim at most 7A. The average load a 12V auto outlet can hold is around 10A (an average of 12V @ 120W. At least that's what cars I've been in can handle...). On standby, expect no more than 200 or 300mA.
• LOUD audio output - Despite it's small size, the receiver has an excellent audio output via a ~2W top-mounted speaker.
• Built-in FM radio - Works from 65 to 108MHz. Good for out in the field or if your car radio doesn't work well.

As with any radio, it also has it's flaws:

• Poor RF final choice - strictly speaking, constantly overdriving your severely underspec'd finals will wear them out within months or even weeks of high-power usage. I'm not really convinced the RF engineers (if there were any!!!) thought about this. The better replacement is around $7 on DigiKey, so that's a plus.
• Instruction manual - Good ol' Chinglish - even harder to learn than both Mandarin Chinese and English combined!!! Just look up some YouTube tutorials.
• SMD technology - Okay, this may not be a complaint, but I find SMDs very tedious to work with if something were to go wrong.

In all reality, that's all I can say about this radio! As you can tell, the pros outweigh the cons for me. Let's unbox and see what is inside...

Official Unboxing

I ordered the KT8900 from Amazon for $80.99. Included, it claims to have the radio, the DTMF microphone, a 12V cigarette lighter adapter, the mount and hardware, and a programming cable.

Right now, I plan on putting this in my new vehicle that I will be buying soon, but instead of permanently damaging the plasticized interior with screws, I would like to mount the bracket with a softer solution, namely, heavy-duty Command strips or Velcro. This should hold the radio up pretty well and shouldn't have a problem with any road vibrations or daily driving. Since this car has a bench seat, there is a good-sized crevice up front that would house this radio pretty well! Less than a foot away is the 12V outlet. In addition, I will be using a standard magnet mount dual band antenna.

Unboxing it, I was pleased from the start. The radio and all its components were packaged nice and neat. I was impressed with the size and I must say it is very compact!

I did want to open it to see what I was dealing with regarding the RF final. Turns out, it is a Mitsubishi RD07MUS2B MOSFET, but the NXP chip I mentioned should work just fine, and I will eventually get one later on. For now, I'll leave it as is, but I will be installing another heatsink. Yes, it did come with the cheap foamy stuff. The small micro-sized cooling fan provided will work just fine.

The receiver is quite crystal clear and it does have a relatively loud speaker, which is perfect if someone is driving at highway speeds. The microphone does seem relatively well built, but don't expect it to survive if it falls on the ground. The lighted keypad is perfect for nighttime driving and provides excellent visibility. The DTMF pad is soft and squishy, and does not seem too terribly hard to press. The PTT button, though clunky, works well. I am unsure about transmit audio since I didn't get around to testing it that far.

The controls are very sharp and I'm sure that this radio will last quite a while. As long as it is taken care of, I expect it to last me for as long as I need it and then some. And hey, if it doesn't work out in the car, I can always make a portable VHF/UHF station with a spare metal ammo can I have!

Final Thoughts

I was moreover impressed that the instructions were in full English with very little typing errors! It's nice to receive a manual that you can understand. Perhaps the QYT model has increased in the quality control department, but we won't know until I take it for a field test. I'm very positive and I'm sure this will do just fine for me.

I really overestimated the size of this thing - it truly does fit in the palm of my hand and I do not have large hands! It is very lightweight but durable enough for vehicular, mobile use with the frame being made out of pure metal. The loud, crisp speaker only improves the clarity of the received signals and I think that this one is a keeper for sure. Replacement parts are quite easy to come by as well, making this radio less of a headache to own.

I now need to make a Wal-Mart run to get some cable clips and Command strips. To save the final, I will probably turn this radio down to about 10W maximum output, which is sufficient for the stock final. The Leixen VV-898 mobile radio has this much power output and I've heard that people can hit repeaters with them over a fair distance away with even a cheap, mediocre antenna.

So, in conclusion, is the QYT KT-8900 worth it? Yes, absolutely. For the beginning Technician and/or those familar with the Baofeng, purchase one of these and use it until you can get a more reputable radio such as a Yaesu, Icom, or Kenwood. Who knows? You may still end up using this full-time in the end!

UPDATE (5/14): I have the radio installed in the car and so far, I am very impressed! I have a little bit of an occasional pop or crackle in the speaker that only comes on if the car is in motion, but it doesn't bother me at all. A filter capacitor on the 12V lines may remedy the issue, such as 10pF for high frequencies or 0.1uF for low-end frequencies. Reception is still clear and the volume is more than comfortable in an automobile setting. I am using a cheap mag mount antenna and I can hit the repeater anywhere in town. I did turn down the power to a value of 10W I assume, but I won't know until I get some more refined test equipment. All I know is that the fan doesn't come on when the radio is in high power for an extended period of time and there's no smoke or burnt smell, so that's a good sign!!!

UPDATE (5/21): Nowhere near 10W originally - more like 0.5W!!! I did turn it up to around 10W now, however, the fan does kick on. I do not really notice power loss as the transistor heats up, and I really don't think the transistor gets stupidly hot! So I think we're good!

To close, I would like to recommend a few things about this radio:

1. MITIGATE THE RF FINAL ISSUE - First and foremost. Either replace the heatsink, replace the module, turn down the power, or do a combination of these. You'd be very sad if you destroyed the final and had to spend a long time replacing it!

2. Keep it out of the sun - Don't put it on the dashboard of your car. Put it beneath a seat, down by the center console, under the arm rest - just as far away from sources of sunlight heat and UV as you can. Heat is the number 1 culprit of failure in this application.

3. Join support groups on Facebook, Groups.io, etc. - Just like the Baofengs, there is limited factory support. Consider joining groups and doing your research on these rigs. Facebook has at least two or three groups dedicated to the QYT line of radios.

4. Use a tuned antenna with an SWR of at most 1.5:1 or less - This will also help keep the radio operating for as long as possible by putting less stress on the final.

If you follow all of these pieces of advice, there's a good chance you'll keep your radio safe from harm for a long time, and this goes for all radios! Truly, the KT-8900 is an excellent base radio for new techs or for the ham that just wants an easy, inexpensive base radio. 

That's about it from me for now! I'll see you in the next post!

Introducing the Hammo Can - portable ammunition for your rig!

 Do you go portable with amateur radio? Perhaps you have a favorite QRP rig like the Yaesu FT-817/818, or a 100W like the FT-891. What if you don't have access to AC mains? Your power supply becomes useless. What if you don't even have a power supply or you're on a budget? Are you sick of your noisy, awful switching power supply? Can you not afford a large and bulky linear PSU?

Well fear not, because I have the solution for you! What if I told you that for well under $100, you can build a portable, battery-powered power supply from an ammo can? Yes that's right - for under $100, you too can make an almost watertight battery pack that will last you in the field for hours! Did I mention that it comes with a USB port for your phone to charge too???