This is the first Chinese PCB I've seen that looks like it is using a real VCO. I know some of the boxed transmitters do, but I've never seen a PCB kit that does. Some of them appear to, but it's just the BH1414K underneath.
I wonder if this one is real. The spectrum looks not bad, but I think that's cause they have the span out so far.
I really hope they don't because then there is no competing with them anymore. The people like Radiomaster and PCS produce quality. I just hope the Chinese never get to that level.
Not entirely sure myself. I know that the WarnerRF FMT5 series has some impressive features, would have to think based on the mpx input that it's doing something other than the 1414, but I may be incorrect. I'd certainly hope so.
HLLY has always seemed a cut above the czh/cze stuff, so I wouldn't be shocked if they pulled it off. Especially with HLLY being a lot more consumer oriented than warnerrf, that could be a game changer for cheap Chinese transmitters.
Not entirely sure myself. I know that the WarnerRF FMT5 series has some impressive features, would have to think based on the mpx input that it's doing something other than the 1414, but I may be incorrect. I'd certainly hope so.
They might have changed it, but last I checked, it's just 1414k under the metal housing.
They might have changed it, but last I checked, it's just 1414k under the metal housing.
Really? I'm actually impressed they were able to get RDS/mpx with it. They sure are good at pushing those chips to the limits. Either way, I guess I'll go ahead and discard my dreams of upgrading to one of those. Loved my TX-30S. Was really good for what it was... We'll see how it continues to shake out for the Chinese transmitters
Yeah, either way, the HLLY is a better price so that takes the WNRF out of the mix if I do decide to go 150w.. And while I would have considered tossing an amp on my old HLLY (which rocks the BH1414K), I really don't like the spectral purity of the T251 (BH1415F), it's definitely more noisy. I had *no* problems inside of my house on my other receivers pushing out the full 30w on the TX-30S, and the transmit antenna back then was only about 5 feet from the receive antenna. My HD radio could still pull in adjacent channels from 50 miles away, which is ridiculously clean and tight. I was absolutely spoiled by that thing, it was my first transmitter and it was an absolute unit.. Not so much with the T251. It's not horrible, but usually within a few hundred feet of the antenna, the band is notably noisier overall.. Adjacents? Not happening. 1mhz in either direction is just noise when I'm that close, and even with the antenna about 100 feet away now, it's much worse.
As for power, I'm tree impeded, and while height is usually desirable, I ran my contour mapper at many many many (many) different configurations, and was shocked at how meh upgrading from 38 feet to 76 feet was (honestly, the mapper can't account for the trees, so I'm sure it'd be better than it's actually showing).. Whereas upgrading from 25w to 150w really filled in a lot of gaps inside of my contour, and would hopefully 'blast through' the trees a bit better. Theres a few hundred feet of trees before the terrain drops down significantly, so power should help get through that. After that, it's wide open and lower for well beyond what I'll ever hope to cover.
Anyways, I'm veering off topic. The problem I have with the HLLY kit listing is it doesn't really explain how much needs to be done. It says 'completed', but it's still a kit.. Do I just plug the boards together, or do I have to solder all of the SMDs on there? (This is a rhetorical question, as I don't think anyone could actually know unless they ordered one).. The pictures make it seem like the boards themselves just need connected, but it's hard to know since the Chinese shops rarely just tell you what you're actually getting :\
Okay, so I'm curious, so I went ahead and pulled the trigger.. Bought the HLLY to see if china has "finally done it"
I did ask the manufacturer about the BNC port for RDS, and they stated it wasn't high-pass filtered and could do full MPX, so I'll obviously mess around with this when I get it next month and post a review in the reviews section.. I know it wasn't your goal to encourage sales of Chinaboxes when you made the post, but I'm genuinely interested now. I'll also fire up the SDR and see how the band fares with the transmitter fired up, since that's obviously usually a concern with the chinaboxes.
Yeah, either way, the HLLY is a better price so that takes the WNRF out of the mix if I do decide to go 150w.. And while I would have considered tossing an amp on my old HLLY (which rocks the BH1414K), I really don't like the spectral purity of the T251 (BH1415F), it's definitely more noisy. I had *no* problems inside of my house on my other receivers pushing out the full 30w on the TX-30S, and the transmit antenna back then was only about 5 feet from the receive antenna. My HD radio could still pull in adjacent channels from 50 miles away, which is ridiculously clean and tight. I was absolutely spoiled by that thing, it was my first transmitter and it was an absolute unit.. Not so much with the T251. It's not horrible, but usually within a few hundred feet of the antenna, the band is notably noisier overall.. Adjacents? Not happening. 1mhz in either direction is just noise when I'm that close, and even with the antenna about 100 feet away now, it's much worse.
Yeah, once you go up to a certain wattage, all transmitters, no matter how good they are, are going to appear to cover stations next to them. In your case it seems like it was really just a better transmitter, but sometimes if you just have a lot of power even with a good transmitter, it will just overload the receiver and make it appear this way.
As for power, I'm tree impeded, and while height is usually desirable, I ran my contour mapper at many many many (many) different configurations, and was shocked at how meh upgrading from 38 feet to 76 feet was (honestly, the mapper can't account for the trees, so I'm sure it'd be better than it's actually showing).
Did you see the post I made on the mapping software? What are you using?
The pictures make it seem like the boards themselves just need connected, but it's hard to know since the Chinese shops rarely just tell you what you're actually getting :\
Yeah, you shouldn't have to solder anything (except maybe the connectors). I got a kit with BH14 a long time ago and it came assembled. I just had to put the connectors on.
Okay, so I'm curious, so I went ahead and pulled the trigger.. Bought the HLLY to see if china has "finally done it"
It looks like they have a real PLL + VCO under there. I don't see the square 1414 or the rectangular 1415. That small chip appears to just be a PLL (which is what you want).
In another image, right in the center of the board, you see a BH1418FV, but because this is not in the PLL section, I suspect it is being used to just encode the stereo signal, but not for the actual RF output which matters a bit more.
So, I think it's pretty decent overall. It could be better if they used a DSP for the stereo (ADAU1701), but if you use MPX input anyway (with maybe stereotool), it's not going to make a difference.
Yeah, once you go up to a certain wattage, all transmitters, no matter how good they are, are going to appear to cover stations next to them. In your case it seems like it was really just a better transmitter, but sometimes if you just have a lot of power even with a good transmitter, it will just overload the receiver and make it appear this way.
The HLLY TX-30s was 30w, the T251 is 25. Both are using the same chip on the finals (the Mitsubishi, actual model number escapes me, but it's the common 30w chip), so the real denominator is definitely the 1414 vs the 1415. Shockingly different. The T251 from what I've seen actually does a pretty decent implementation of the 1415 compared to others, but there's only so much you can do with it.
My little HD radio is extremely competent at rejecting adjacents (its not an actual f1hd, but it's the same internals). I regularly pull in stations adjacent to a 50kw that's about 10 miles away, the only radio I have that can do that. At the least, it's a good Canary for whether something is overloading. While I don't expect adjacents to my station from 100 feet away, I at least think it should be pretty graceful with the rest of the band. Will obviously test this as well as part of my "spectrum purity" test.
Did you see the post I made on the mapping software? What are you using?
I did not see your post yet, I will look for it right now though (edit: found it. CloudRF and RF-toolkit. Have played with both. Fun fact: CloudRF is actually a fork of SPLAT!, but SPLAT! is fully free and I can run it infinitely so I'm biased towards it). I'm running the latest splat (sorry, SPLAT!) release, which has proven to be fairly accurate so far. However, disappointingly, the main town I'm "in the yellow" for doesn't do so well currently. Picket fences like crazy. I can go another 10 miles and well "into the green" and it sounds very similar.. I really think those trees are murdering the power output.
Yeah, you shouldn't have to solder anything (except maybe the connectors). I got a kit with BH14 a long time ago and it came assembled. I just had to put the connectors on. (...) So, I think it's pretty decent overall. It could be better if they used a DSP for the stereo (ADAU1701), but if you use MPX input anyway (with maybe stereotool), it's not going to make a difference. Nice avatar
Thank you, and this is all good news, especially liking the avatar. Figured you might with your clever play on words that is your name
I'm actually pretty excited about my purchase. Been quite underwhelmed with the T251 overall since having to replace the HLLY. It's been a competent little box for what it is, but I hit the limits quickly and it was definitely a downgrade overall. I'm definitely losing power to those trees as well, but my overall range tells me there's hope.
I'm also excited for mpx. Been wanting this for years. Generating my own stereo signal adds so much flexibility to what I can do. And RDS should be a fun bonus too.
Also noting, I did have interesting results with jMPX as well. I never had stereotool RDS work, but I did have RDS (but not stereo, because the low pass was lopping it off) on the HLLY by hammering it through. It needed a good strong signal to decode, but it did work. Shockingly. Obviously having a proper setup will help me get it working with stereotool. Excited to get started.
The Chinese have finally done.... Something... I haven't been able to test MPX yet, but the audio input is.... Well, bright might be an understatement. I have the bass up at +12db and the treble down at -12db in stereotool, pretty much a backslash in the EQ.. and it's still pretty harsh, but finally tolerable. Still lacking of any real bass, even with all the enhancers cranked up.. So there are certainly some issues there. It's also reading notably higher in SWR than my RigExpert reads at the same frequency (2.2 instead of 1.4). Also, it's not fully adjustable power-wise. You can set it lower than 20, but it's just going to ignore you and put out 20w. Also, the BNC connector for MPX is tricky. There's a bracket for the audio inputs, but two of the holes are empty, and they just include a BNC connector and some coax. But how exactly do you connect coax to pins in a connector that lacks anything? It's doable, just poorly thought out. Also, power for the main board didn't include a connector, so to get it running, I ended up having to solder some wires onto the pins. No biggie I suppose, but definitely not thrilled with the sound quality so far.
Running it at 80w, since my antenna is only rated for 100w and has had numerous repairs done over the years, so I'm wary of trying to push 100w through it right now. I myself haven't tested coverage, but my brother at work tried it out and was pulling it in there in the parking lot. Will have a better idea of coverage once he leaves work and can drive around. I'll keep tweaking the sound here and try to get it a little better, but man, the lows are awful, and the highs are just so bright.. Very disappointing sound quality, but the thing is an absolute unit.
I'm not ashamed to admit I jumped a little when the cooling fans for the amplifier kicked on after a minute or so. They're loud and sound extremely angry. Those things are no joke, and they move some serious air.
But a huge confirmed improvement: I'm still pulling in second-adjacents 'full bars', and can still hear first adjacents... Just not nearly as well. So even with more than 3x the power, it isn't trashing the band like the T251 was. I intend to fire up the SDR and check for spurs, but in tuning around the dial on my Sony in an informal test, other than the first adjacents, it's shockingly clean. Still pulling in HD signals on stations ~50 miles away (the HD signals are 1% EIRP of the originating station, so those usually get destroyed). Overall, that is a huge improvement.
I have more tests to do and am still tweaking the sound. Was honestly shocked at how quickly it arrived from China, they were estimating another month, but it showed up today and I figured I'd share some of the preliminary results.
EDIT: I did a recording on my phone.. Which has a terrible radio.. But I also tuned to other stations so you can hear the difference. It's still not sounding right, but this is shockingly the best I've gotten it so far. Believe it or not, I have the bandpass cutting off everything over 10k, and that seemed to be the most reasonable result so far... It didn't solve the bass issue, but.. Whatever. You can hear it at 953fm.cc/pirate.mp3 - I should really just get a new sound card sooner rather than later so I can do MPX -_-
Another edit: The signal results of the drive were....... Outstanding. Areas with no previous signal due to terrain were almost completely clear for 5-6 miles in our second least favorable direction (the only direction tested currently), and there was intermittent reception to about 15 miles away. Previously, we only had about 2-3 miles in that direction of 'acceptable' reception, and about 6 miles of 'i can still hear it but its annoying to listen to' coverage before it went into unlistenable static (it pretty much went to dead static after 6 miles due to a hill, whereas now it's still audible after the hill, but still not clear). And we're still only pushing about half of what the transmitter is capable of, so definitely an exciting result. However, not all positive. A downside is our edge reception and the AGC on the car radio are definitely butting heads. The AGC is absolutely not liking the signal at the fringes and very aggressively reacting to it, which was not an issue with the T251, nor with any other station on that radio. This should hopefully be resolved with a proper MPX input.
My brother has stated that "we sound like a pirate" now.. Whereas with the T251 and good processing, we blended in quite well. We have more work to do, but I'll keep everyone posted.
Post by ogrevorbis on Aug 24, 2019 19:45:36 GMT -6
I'm surprised you got it already. I think your sound issues have to do with the 50uS pre-emphasis that they use in china. Since it isn't the type of all in one chip that has the pre-emphasis built in, I think it should be rather easy to modify it to 75uS. The hard part is finding those caps responsible for the pre-emphasis. If you are going to do MPX anyway, then I'd just wait for that sound card instead because that will be much easier and better than trying to mod the board. You may end up finding better performance by lowing the RF output by decreasing the supply voltage instead of limiting the power in the screen. Some Chinese transmitters are not matched perfectly and they tend to put out more noise and spurs when you limit the amplifiers drive power (which is what the LCD adjustment usually does) rather than changing the supply voltage. Those MOSFETS work the at the best efficiency when given full drive with lower supply voltage. You may even notice the fans coming on less often this way. Hopefully they aren't 48V fans because then that might not be doable. Those Chinese transmitters often read a higher SWR than it really is (I have one of the 30W ones).
I'd definitely get that sound card. You don't even really need that expensive a card. Some realtek on-board audio is good enough for MPX, but it's still better to get a dedicated sound card because sometimes those on-board audios put out some high frequency spurs.
Good luck. I'm interested if you ever pursue that micro-power transmitter network thing. If you ever do it, let me know how it goes.
Unfortunately, the realtek in my computer maxes out at 96khz. I have a laptop with a realtek that does 192khz, I may enlist that for some further testing before I commit to buying a good card for it. May just actually replace the entire computer since that one is a core 2 duo and it didn't let me upgrade it to a quad.. which really would have given it the breathing room it needed.
Now I run into further questions, though.. I assume the coaxial input is just standard mono analog audio, but do I need to match the impedance? Do I have to disconnect/disable the regular audio input somehow so they don't conflict with each other? This part is new to me, I've never done mpx input...
Also, the original 30w HLLY was 50us and didn't sound this bad, we eventually got it to 75us, but overall, there is definitely some shenanigans with the audio chain on this thing.. it's very meh.
I'm going to go ahead and say the Chinese have not done it. Not right, at least... The RDS input (coaxial) does nothing (though perhaps I'm doing it wrong.. But how hard is it to attach mono audio to two pins? And one could say maybe it's high passed? Nope. Nothing, they appear to be dead pins). However, there is no low pass on the audio input, so the only way to get MPX into it is to just dump it into the audio chain... And it sounds absolutely awful. I already hated that audio chain, but trying to do MPX into it results in one of the most awful sounding things I've ever heard (and yes, I switched it to mono before I did this.. Not that the on-board stereo generator was any better). Yeah, it "technically" works, full RDS and everything.. But I've resorted to transmitting in mono because stereo sounds like a waterfall of weird warbling and knocking noises... I can get stereo to sound "decent" by turning on multipath stereo and setting angle limit to 0 degrees, but it still sounds tinny and awful, even in mono. And that's with the audio level at about 25%. It sounds like I'm trying to push a 50w audio amplifier through headphones. Just awful.
I'm certain I could tweak some stuff on the frontend to fix it if I was more confident in my circuit modification abilities, but I have a lot of homework to do before I start messing with a $400 transmitter, considering I'll be paying for this over the next year (yay paypal credit!). But out of the box? I am extremely disappointed in the sound quality. It is by far the worst transmitter I've ever owned for sound quality. No hesitation, no question. It sounds awful. My bh1415k runs circles around it. My CZE ST-7C sounds like a pro station compared to this awful sounding setup. If not for the ridiculously good range I'm getting now, I'd call it a total bust.. But what good is range if it sounds this bad?
Including some pictures of the kit. It's been pulled from service until I can investigate some possible solutions to the awful sound quality, but hopefully this proves to be useful for people.
If the links don't work, please let me know.. Not sure how Discord is with remote linking like this, but I didn't want to recompress them, and reuploading elsewhere seemed like a little more work than I wanted to do right now.
Including some pictures of the kit. It's been pulled from service until I can investigate some possible solutions to the awful sound quality, but hopefully this proves to be useful for people.
If the links don't work, please let me know.. Not sure how Discord is with remote linking like this, but I didn't want to recompress them, and reuploading elsewhere seemed like a little more work than I wanted to do right now.
I can see the links.
It is an independent VCO + PLL type transmitter, so there should be a place you can couple in the audio directly to the VCO. They probably didn't design it for that, but you should be able to figure it out if you poke around. When you hook it up, are you sure you are bypassing the BHxxxx and the JRC completely?
That 150W amplifier is good. I own one that came separate without the TX and pre-amplifier. Maybe you could couple in one of your better transmitters. You'd have to sample the RF before it goes to the amplifiers though.
I wish I could offer a better option. You need a good TX with output of only a few milliwatts. Maybe put a Ramsey or something into that gold coax I see going to the amplifier. That would work.
Come to think of it, see my next post on the next page. . .
