Power vs. quality for Tx.

[ChrisL]

 I finally got my BTECH 50x1 to work at 15 watts on two different repeaters fairly well. At 5 watts It works but has alot of noise in the signal. I cannot improve my antenna situation any more than I already have due to HOA restrictions otherwise I wouldn't be posting this. I'm considering the Kenwood TK-880h but it may only have a 10 watt low power setting. I want to keep the TX power as low as possible.

 Here's my question, will the better quality Kenwood sound as good or better at 10 watts than my CCR - BTECH at 15 watts when I transmit?

 I just don't want to invest a lot of time (programming learning curve) and a bit of hard earned cash and find out that 10 watts isn't enough.

 Thanks in advance for your help in this matter.

[JohnE]

the 880H would be a waste IMO as it is 40W capable. If you're going to run at 10W just get an 880 that runs at 20W.

as to the quality of the audio that would be subjective. I can't speak to the Btech but I am a long time Kenwood guy and happen to like the audio quality and features of the Kenwood

5W vs 15W has to do w/what you need to overcome the noise floor and have a clean signal into the machine.

on a side note the Kenwood software is very intuitive and simple to use.

JE

[berkinet]

As you describe the problem, it seems the noise issue you have is based on reports from other repeater users. If that is the case, you don't have a lot of alternatives -- transmitter quality is probably not an issue. If you only use one repeater, or the two repeaters are in the same direction from your home, you could change to a directional antenna (it would look a lot like a UHF TV antenna and might not incur HOA wrath), or use more power. Note, the difference between 10 and 15 watts is negligible ~1.75dBm.  So, just changing to a better quality radio is not likely to yield much improvement.

 

On the other hand, if your problem is the received signal at your radio, then changing to a radio with a better quality receiver could make a big difference. As discussed in several threads here, the cheap imports have low quality receivers and that might be your problem. Also, a directional antenna and/or better coax would give you a stronger received signal as well.

[WRAK968]

the 880H would be a waste IMO as it is 40W capable. If you're going to run at 10W just get an 880 that runs at 20W.

as to the quality of the audio that would be subjective. I can't speak to the Btech but I am a long time Kenwood guy and happen to like the audio quality and features of the Kenwood

5W vs 15W has to do w/what you need to overcome the noise floor and have a clean signal into the machine.

on a side note the Kenwood software is very intuitive and simple to use.

JE

 

To follow up on what John said here, Kenwood is a commercial/Emergency use radio, which means the quality is there, but I believe the interference between the roof and any power/cable lines run through the roof is your main culprit. I doubt anyone here could tell you is 10W is enough to get out cleanly but it would get out better than 5W.

 

The main questions is, do you have a reason to run a 40W radio when you only plan to run 10W. If the answer is that you plan to only run 10W, TK880's sell for like $50 or less. I've gotten all of mine for around $30 by waiting till the right deal came up. 880H's are a bit more expensive, usually about $75-100, so the cost alone may be a reason to get the lower unit. If your goal is to try and reach a distant repeater with the higher output there are other factors you need to consider. such as building materials and construction.

[JohnE]

forgot to ask about your antenna system

what are you running? cable type/length and antenna

[Logan5]

Less watts and better antenna. You could get an exception to use a TV antenna, so make your UHF radio antenna easily attachable to a TV for proof if needed. If the complex offers MASTv, You may find a UHF TV channel that they do not relay through the provided cable. If you are ultimately forced to an indoor solution, you could attach a Yagi antenna to a fordable tripod and deploy in the house or on a terrace when needed. More watts seldom improves a less than ideal situation./

[RCM]

We're really limited in how we can help you without a good description of your antenna, its feedline and mounting position.

[ChrisL]

Thanks for the help guys, I appreciate the advice and help with this. I can say that the receive side of the radio is fine to me. I'll have to try my yagi and 15' of Belden-7807A, RF200 outside and see how it performs.

[Radioguy7268]

How many elements does your Yagi have? Do  you know the dB rating? Most of the time a UHF Yagi would have 3 or 5 elements. More elements would usually equal more gain, but also give a tighter beam or higher directionality to the antenna. Do you know for sure the compass heading to the repeater(s) you are trying to reach?

 

Your feedline is minimal (rated 6.5 dB of loss / 100 ft. at 450 MHz)  but a 15 ft. section shouldn't be killing you, provided the connections are proper.

[berkinet]

...Your feedline is minimal (rated 6.5 dB of loss / 100 ft. at 450 MHz)  but a 15 ft. section shouldn't be killing you, provided the connections are proper.

... and you have no adapters!

[intermod]

You noted you want to keep your power as low as possible.   Just curious what the reason is.  

 

I agree that the difference between 10 and 15 watts is negligible (+1.75 dB).  Most users (including me) can barely notice a doubling of transmit power (5W to 10W, or +3 dB), even if the user is noisy; they may start to notice a difference if you quadrupled your power (5W to 20W, or +6 dB increase).  I always try and improve things by +9-10 dB to make a noticeable difference.

 

While 9 dB can be attained going from 5W to 40W in one shot, you likely have a good reason for not going there.  So get this 9-10 dB from a combination of things - maybe increase power slightly and improve antenna gain slightly.    

 

Maybe go from 5W to 20W (+6 dB), and use a yagi that **has 3 dB greater gain** than your current antenna.  That gets you 9 dB total. 

 

Your cable loss is like -1.2 dB (cable plus connector losses).  You could halve this to -0.5 dB using better cable (e.g., LMR400 cable), but the cost is high for little gain, considering you are aiming for 9-10 dB overall.

 

If possible, change antenna height/position to eliminate close-in obstructions (buildings, trees).  This can give you 6-9 dB in one shot in some cases.

 

Finally - if the radio has a "Wideband/Narrowband" setting, make sure you operate "Wideband" or "Wide" if operating through the vast majority of repeaters.  This alone can gain you +3 dB of effective improvement, particularly if you are already weak.  

 

Also - if you have a SWR or watt meter, or know somebody who does, make sure the antenna system is performing.  Also - make sure you are not trying to use a UHF amateur radio antenna designed for 440-450 MHz, for 462/467 MHz.   Some amateur antennas work great on both, but most don't. 

 

Sorry for all the math.  We use dB because the values can be easily added and subtracted; easy math for my simple and lazy mind.             

[RCM]

I agree with keeping the power as low as possible. The reason I ask about your existing antenna is a 1/4 wave ground plane on top of your house will probably outperform an omnidirectional gain antenna in your attic. And it's not hard to hide one. I make them out of panel connectors and thin copper wire. A thin 6" wire is almost impossible to spot on a roof, especially if you give the connector a light spray of flat brown or black paint.

[BoxCar]

I'm curious as to the HOA restrictions. The FCC has ruled against many associations having rules against external antennas. If that is the underlying issue, send a copy of the association's rules to the FCC Wireless Telecommunications Bureau and ask them for a ruling. It may be their rules violate FCC regulations and are now unenforceable.

[Logan5]

You can purchase Belden products in many colors, easy to match the color of barrel tile, shingle or trim colors. a Mag mount antenna can be attached to any steel exhaust, kitchen or bathroom vent. Although not an ideal ground plane, again will out preform any indoor deployment. You will be amazed what you can make happen. Especially if you have the extra cash for the upgrades.

[ChrisL]

 Once again, thanks for all the well thought out reply's.  The reason for the radios is for emergency purpose. I want to run as low of power as possible to save energy in a power outage. I have quality agm batteries to keep things going and solar. I am barely able to get into 2 different repeaters on 5 watts with my BTECH but my signal is nearly full quiet with the BTECH at the 15 watt setting. I'm using a diamond 400 meter and needle barely moves when I check the SWR (far below 1.5).

 My understanding with the Kenwood 880 and the 880H is that the 880 is 5 watts on low and the 880H is 10 watts on low. So, I wondered if the Kenwood's 880H signal at 10 watts is cleaner than the BTECH's so it may sound as good or better than the BTECH running 15 watts.

Most of the reply's seem to refer to the antenna and I believe all of you that it would make all the difference in the world to improve on but at the moment I can't. I do however want a second radio that is repeater capable so I figured I may as well get some advice.

 Something I do like about the BTECH 50x1 that I would lose using the Kenwood is the ability to monitor VHF and having an FM radio. Probably considered gimmicky but I do like the features, (at least it doesn't have a flashlight).

 One more thing, the Kenwood's do have CTCSS correct, since that is what our local repeaters use near me.

 

 Thanks

[intermod]

Both have CTCSS and DCS.  Some repeaters in metro areas may require a different CTCSS or DCS code on the input than the output, and others may use DCS in their input, and CTCSS on their output (provides a slightly higher level of protection form unauthorized access).  This mixed-code capability is often a differentiator on some radios.  Kenwood will do this, and I think Btech will as well (not confirmed).   Not sure if any of your repeaters even operate this way.  But if you listen in carrier squelch it won't matter.  

 

Kenwood has a reputation for great sounding audio, but Btech does not seem too bad either.   I don't think your comparison will be significant. 

 

Suggestion: even in some emergencies, most radios are in "standby" (not transmitting or receiving).  As a result, the most dominant component of power draw over time can be its standby power, not its power draw during transmit if the radio will be powered up 24/7 (alas - btech does not provide this spec; its 0.4A standby, 1.0A on receive for TK880).    

 

Tough call....

 

Greg

[RCM]

If you have a line on a TK-880H, I recommend that you get it. I'm quite sure you will never regret it. I also recommend the standard TK-880. You can turn the power down internally. The service manual (which is available all over the Internet as a free pdf) shows how to do it. If I were you I would just get a standard TK-880 and set the high power to the minimum that does what you need; whether that be 25 watts, 15 watts or whatever. 

Then if you are ever able to upgrade your antenna system, you can turn the power down further.