K-ROCKS has both FM and AM facilities as well as online streams.
The AM consists of two LPB AM-30 transmitters modified for C-QUAM AM stereo using the Chris Cuff (Alfredo) C-QUAM exciter boards. One transmitter is on a hot-standby state and the other is on air. Both are fed into LPB's TCU-30 line couplers feeding the neutral wire. Coverage is 4 solid miles and on rainy days, extends to well over 8 miles.
The LPB units were second to none in craftsmanship and long term dependability. The design is simple and easily field serviceable. Even years later after the LPB company has all but disappeared, replacement parts are still available, making any one of the solid state LPB units well worth their weight in gold. My avatar picture shows one of the LPB units on air with the C-Cuff C-QUAM exciter board installed.
There was only one drawback to these particular units. The factory exciter board, though well designed and excellent component layout, they suffered from nearby inductance influences near the exciter RF power adjustment pot, making the power adjustments a real nightmare, and often at times blowing the finals due to the inductance effects causing the power level to swing wildly. LPB used a stand-up potentiometer mounted on the PC board, basically turning that adjustment pot into a little radiator and anything within a 4 inch range such as a hand or even a screwdriver would throw off the circuit impedance, thus shifting the power level.
The solution to this was to replace that pot with a trimmer pot that mounts flat and flush with the PC board so that a non-conductive tuning tool could be used to adjust the pot. It would take a direct contact with a finger or metal object to the top of that pot to make it go crazy, compared to just moving your hand within 4 inches with the older style pot.
On the collection shelf I have the Panaxis AM-100 and AM-5000 amp, a much older LPB AM-6 tube unit, and a Harris STX-1C C-QUAM exciter, plus various other home built units of tube and solid state designs and linear amps.
The FM side..several tx's over the years. Out of all that, probably only two really worth mentioning.
First is the Panaxis FM 10 watt unit with the ENC-1 case. It has the SG module, the FM-10 10 watt amp and PS. After including a small 1 inch 12vdc fan, it has stood up to the test of time and on air endurance. Spare parts are still available including the PLL chip which is a DS8907 available from UTSource. This unit serves as the full time on air tx.
There is also a Ramsey FM-100 unit with the various modifications for improvement around the BA1404. I also added a 2nd output stage prior to the final filter for better performance from that filter. Running a cool 50mW, it drives a home built 25 watt amp. This unit serves as a hot stand-by. I purchased this kit back in "97" and it still runs as perfect as it did the first flip of the switch after assembly.
I also have 3 of the CZH units from China. These are more for collecting purposes than on air use, however they have proven to be highly reliable and clean with some minor adjustments of their final filters. I have the 1/2 watt, the 1-7 watt and the 1-25 watt units.
Along with the CZH units sitting on the collection shelf are several home built FM units and amps.
At my station's forum is a section about AM Carrier Current with a few detailed photos of the setup and short article about Carrier Current broadcasting.
Peace!
K-ROCKS RadioOne
ZeroPointRadio
AM Stereo 1670
FM Stereo 92.1
Post by sgtpeppers on Aug 13, 2011 21:05:37 GMT -6
The CZH-7C transmitter for FM
Piece of junk, thats the basic on this. I didn't see much of the harmonics in this unit surprisingly. The problem I have with these transmitters is that they do not have sufficient output. I purchased off ebay (already a bad idea) and the first one that was sent had an output of 0.2 watts. I complained to the seller and they sent me a new one that had an output of 4 watts. I decided to open up these transmitters and realized why the output was so low. The transistor inside was the fake rd06hvf1 transistor.
All in all, I would reccomend this to someone who's looking to spend $60 on a over sized low quality in car transmitter for your ipod.
Maybe you got one of the "copy cat" units that flooded the market about a year ago....
Unfortunate. The "copy cat" units fell under various brand names like FmUser and HILLY and were first put into silver cases, then later they included the black cases.
The copy cat units do use inferior components at key areas such as the RF final. These also cut corners around the 1415 using flaky surface caps and resistors, not to mention the use of incredibly weak solder that cracks at the slightest bump....plus on top of all that the reported spurious junk they throw out.
Good thing tho is that even those copy cat units and their problems can be easily corrected so they are up to spec like the originals that came out 2 yrs ago.
Peace!
K-ROCKS RadioOne
ZeroPointRadio
AM Stereo 1670
FM Stereo 92.1
Hlly electronics and FMuser were the original producers of the czh brand transmitters. Hlly electronics has great transmitters, compaared to other czh models on ebay, the ones on ebay are made with extremely cheap parts, Hlly's transmitters are more well built, and built with better parts than the ones all over ebay. In fact, right now I'm using a 20 watt unit right now as I type this.
Post by Ozone Express Radio on Sept 8, 2011 20:18:23 GMT -6
I have to add, I have two of those HLLY units, along side a homebrew TX, and I have had pretty decent results from the Chinese transmitters.
Filter them really well on the output side, and feed them a good supply of regulated voltage (not the power supplies they come with) and keep them cool. They will do what they are designed for, given the price. Want a really good TX? Plan on spending a lot of money or doing a lot of time researching and building your own. You really do get what you pay for in anything.
ELE EL-15H sounds excellent and has great output when it's working. But I have 2 units that have started to heat up during normal use and the power output decreases with the heat. I had to put a cpu fan on it to keep it cool, otherwise the power drops to nothing. Even with the fan it's not outputting 100% now. I believe this is because of some crudely designed circuit that allows you to decrease the RF output with the volume knob, but after some minimal use it begins to malfunction.
I have an HLLY 5watt unit that seems to be more solid, but it doesn't sound as good.
Could you effectively scan for spurs and harmonics with a police scanner? It may be lo-tech, but is easier than finding a spectrum analyzer.
If your only concern was dropping into the police/fire/emergency bands, then I suppose you could, but the other problem would be not so much actually hearing your broadcast on those channels, but simply causing some undesired interference that you may not recognize. Noise, static, etc comes to mind.
Could you effectively scan for spurs and harmonics with a police scanner? It may be lo-tech, but is easier than finding a spectrum analyzer.
If your only concern was dropping into the police/fire/emergency bands, then I suppose you could, but the other problem would be not so much actually hearing your broadcast on those channels, but simply causing some undesired interference that you may not recognize. Noise, static, etc comes to mind.
My biggest concern is interfering with emergency bands and hams. I am in a rural location with a HLLY CZH-15. I like it but have read it causes nightmares. I can't afford anything better though.
SWR meters are for wussies. Just pump up the Volume!
Post by The Hamburglar on Dec 18, 2012 3:48:25 GMT -6
I have an older HLLY CZH-15A that has been decent. It doesn't seem like a copycat tx, but it came with 50us pre-emphasis and I need info on how to change it to 75us to improve the higher frequencies in my broadcast. I know it has to do with messing with caps, I just don't know the full story. Help needed!
SWR meters are for wussies. Just pump up the Volume!
CZH-7C and CZH-05B work great for me, great sound. Distributor is SainSonic who did a 75us pre-emphasis modification for me. Range is decent with stock antennas. 500mW version goes about 700 feet and the 7W version goes about 1.5 miles. I recommend these. I believe the actual manufacturer is HLLY but re-branded as SainSonic as the internals are marked for "FMCZH - HLLY"
Going to purchase a TX-10S from HLLY here soon which is a bit fancier but a bit more pricey too. Will post how that is. The internal shots show it uses a WRF-05A amplifier instead of a Mitsubishi MOSFET alone. Will see...
Received HLLY TX-10S today. VERY well made device. Although the features are limited to what I originally believed would come. I originally thought you could adjust the power, but you cannot do so. Never the less, it has a WNRF-08A amplifier circuit (puts out about 9-10 watts) and Vastelec V-FM02 Exciter board and such. The construction of the actual box is fantastic. The PCB boards look to be in excellent condition and the Vastelec board looks to use some higher end spec ceramic components which was a shocker to me. Can select between Mono/Stereo, full range of FM frequency. Comes with a built in 5 pole Low Pass Filter, very nice. There is a way to change the output power manually using a little turn knob inside on the voltage controller pcb board which feeds the amplifier 10Volts regulated continuously such that it produces maximum power. (decrease that voltage and decrease power). Overall, very good sound quality. Absolutely zero hum compared to cheaper products like CZH-7C which have small hum. Sounds is beautiful, has selectable 50 or 75uS pre-emphasis.
It is ma bit over-priced in my opinion and talked up more than it's worth, but in the end, it is MUCH better than the CZH products. Very nice, and the parts and the box are very sturdy.