The guts of a CZH (chinese) transmitter

[OnKeys]

thought I'd buy, and then crack open one of those shitty sproggboxes that everyone talks about; fuck me it's worse than I thought!

http://s24.photobucket.com/user/Audicti ... s/library/

[sharky]

Nooooooooooooooooooooooooooooooooooooooooooooooooooooooooo!!!!!

[OnKeys]

haha don't worry; it's never going to be used or even plugged in for that matter

[james_wilson16]

I have one of these somewhere. They are awful. Brought it to have a look inside

[Uksoundz]

Ive always wondered how many people have these small 7w Chinese transmitters playing bedroom FM. Bet they sell tons of em. Never had one myself but can imagine if these had been around back in the day it would have been fun when I was a kid.
Planes would probably fall though from what I've heard about them!

[teckniqs]

There's probably loads of them on but they only put out 7w on other bands so you'd probably only hear about 7mW of signal on their FM frequency. #DowntotheendofthestreetradioFM

[Pants]

I got an st15b and I tested from a soil stack with a single dipole and could hear it 10mile away lol

[MiXiN]

What's a soil stack?

[teckniqs]

I'm guessing he means from down very low, out in a back garden?? (maybe mounted on a compost heap)

[Dai Pole]

What's a soil stack?

The sewage pipe/vent/overflow.

[Pants]

Yes shit pipe that sticks out the roof of a house to let the pooh particals out away from wafting under ya nose

[ragga]

Yes shit pipe that sticks out the roof of a house to let the pooh particals out away from wafting under ya nose

...sort of , soil stacks that clear the eaves and stick up in the air with a vent on top ,their main function is to stop any pressure/vacuum problems with the plumbing undeneath.
if you launched a big log or two with paper down your bog it could create a partial vacuum on the way down , enough to disturb the functioning of any other devices plumbed into the stack. That turdy wadge could suck a lot of water out of your pipes on its way down and for instance leave the trap (u bend) in your sink empty of water. this means nothing is preventing the bad air from your shit pipes wafting into the bathroom. mm mmm

good place for a stealth antenna

[koopa]

Has anybody ever really thoroughly tested all the Chinese stuff on proper test gear and if so is there any video clips to see it live in action ,I'm no way whatsoever able to or even know how to properly test for harmonics etc .but how do people know how bad they truly really are and what makes them so crap is it the layout ,the parts or the pll chips they use ,I know anyone talking about Chinese stuff gets a ribbing but just like if someone says somethings real good you want to know and see why so same goes for what I'm told is pure shite .it's all a big learning curve good or bad

[MiXiN]

For the most part, I think the problem lies with the lack of LPF filtering.

The all in one PLL chips are also known to be pretty grim as well as far as I'm aware.

There must be a lot of these by people who aren't in the know as they seem to be selling quite well over on fleabay.

[FMEnjoyer]

one a clear freq with height they could go 15 miles all diorections 7watts but shame they sprog surprised you cannot hear a few on at any one time given there popular surly filter is a few bits of coily wire and stuff about 10p of bits why they not do that on the pcb, maybe they are actually good and rig bulder want you to feel they are bad it is suspious that noone who build rig show the sprogs. i smell a rta

[teckniqs]

We have no idea how high his TX antenna was mounted and looking towards the end of the video it looked like he was on high ground with mountains seen in the distance.

@MiXiN, they have LPF filters it's just the amount of mess they produce is too much for them to be able to clean up...

[shuffy]

Having seen photos of a few of these things, they generally don't seem to be lacking in LPF filtering on the output. The overall layout of the one at the top of this page is nasty though. I'm assuming that the main criticism associated with these things is sprogs within the band, or general nastiness caused by the junk thrown out by these BA1404 or similar which they insist on using.

Someone posted one a few weeks back with a blue board with an RD30HVF1 (possibly not a real one!) on it, but I can't find the post now. The PA and output section looked fairly well laid out and the matching didn't look far off the mark for that device but there were some things about the audio and exciter side of it I couldn't work out - there were two 3.5mm minijacks on it and looked like perhaps you had the option of BA1404 - or not. Nice.

[pjeva]

LPF will lower harmonics probably above 130MHz. Problem with this and similar "boxes" are so called 'in-band spurious' signals. It means that if you transmit at 90MHz, you might have signal at 93MHz and any other frequency in FM band. Filter is not designed to wipe this out because it is designed to pass any frequency in FM band. Most certainly with 90MHz transmitting frequency, you will have spur at 107.6 because of quartz crystal used for stereo coder, for example. There is solution for this and it is very narrow band pass filter which is hard to set without expensive equipment and must be retuned whenever you change frequency. And you will get only few watts at wanted frequency... not full power.

[Maximus]

How about this for a sprog box... BTW it's good to be back. Big respect to Admin for bringing RN back to life!

[pjeva]

How about this for a sprog box... BTW it's good to be back. Big respect to Admin for bringing RN back to life!

What a Frankenstein!!!