Відео

Certainly a blast from the past, a friend and I made our own 934MHz CB by a bit of creative engineering using a Key UHF mobile radio combined with some electronics from a luggable cellphone. (Retaining the VCOs, prescaler and receive IF from the phone). Obviously not type accepted but a challenge, particularly to get it all to fit in the standard PMR case. Possibly the worst 934MHz CB was the one that transverted from 27MHz, (Grandstand Bluebird) it relied on the operator setting the 27MHz rig to CH1. How it got type acceptance is beyond me... The strange offset in frequencies of the CB27/81 spec radios was partially to give UK manufacturers a head start. No sign that it really happened, PLLs with internal ROMs could take care of that quickly.

I think, there were different output power on different frequencies! And you have to know your 'partners' -number, to connect them, ... ! A very difficult system! 73 de Markus - db9pz - JN39fq 3miles/5km east of LX !

These were brilliant back in the day, a few hundred miles was easily achievable with the right conditions. Bought a good few in the late 80/90s for peanuts and sold a couple for daft money over lockdown. As far as I’m aware there still a bit of a 934mhz community.

Likely a Toshiba or Mitsubishi PA module. The hybrid modules were popular back then thru 1300mhz. Had a 912mhz repeater using a 10 watt module here in the late 80's. Was a waste of time and money (except for the learning aspect) and never got used. Lot of low powered utility telemetry interference on those frequencies now, smart metering etc. I believe cellular has completely abandoned 900. Also, many broadcast STL point to point links are still located above 925mhz here.

Thanks Nick. I remember there was this additional CB band, which went virtually unused due to the cost of the kit. My FT290 2m multimode set cost around that sort of money - but much more useful, and believe it or not, it still works 40 years on.

Interesting bit of kit Nick. I didn’t know about the existence of such band. Thanks for sharing also the story at the beginning. Diego

Nice fix, also appreciated the short treatise on the difference between UK and US CB radio. I wonder just exactly how long that expensive radio was useful between the sale date and the cellphone date. Thanks Nick.

Thanks Nick, a very interesting rare beast. Keep warm in your shed mate 😀

Take care of yourself. I try to take a emergenc-C Sudafed and a anti-biotic as soon as i feel a tinge coming on. Nips it right in the bud.

Fast rise, short duration pulse backed by a Multi-Megawatt driver. That's what the military calls MOJO. Cheers Nick, late to watch, too much work to be done before the big chill here.

Regarding resolution - it can be higher, with gate time 10-15 seconds. But it is only suitable for long-term measurements...

Hey is there anything I can do to make myn go abit faster😢

Hello mate I have 20miles travel twice a week to work single charge miles and suggested this bike or not ?

The HP8903B datasheet show a 3% measurement error at RMS levels used in the video. Also, the distortion measurent does not seem to go below the higher of -80dB (100uV) or 15uV (-96dB) (I do not understand that specification the way it is written) A reading of 0.001% is -100dB distortion. The testset display does go down to 0.0001% which means -120dB (1uV) This makes the "the higher of -80dB (100uV) or 15uV (-96dB)" statement weird once again. As for the PCB and parts, the shorter the leads, the better the circuit. I do wonder what a spectrum analyzis of the output could show. Some oscillators have a FET in the loop used to kill most of the second harmonic. I bought a Chinese low distortion oscillator and, through adjusting it, I was able to get: -96dB THD+N (0.0016%) at 999.95 Hz. - 102 dB THD (0.0008%) at 999.95 Hz. The board was sold with a claim of -124dBFS distortion. With an output of 16.3dB (6.5VRMS) the measured THD is -118.3dBFS, which is not quite the claim. Driving the board with two 9V batteries, the SNR got 3 dB better. SO did the THD with -105 dB (0.0006%) and 119 dBFS (output = 14V RMS) The 3 x 10 turns potentiometers were not optimally adjusted, so some tewaking was needed. Measurements were made with a QA403.

Those two diodes in the beginning of the video are a simple OR gate. If PLL 1 OR 2 takes the lock detector low, it will activate the error signal and flash the display. If both PLL LD outputs are high, the PLLs are locked, the fault is then elsewhere. The third input is to deactivate the LD for the higher ranges. Let me watch the rest of the video, I may comment again.

I have this amp I brought it new from Lazkeys in Birmingham in 1983 , I `ts had a minor repair and it`s still going strong and a Fantastic AMP , A facinating video and I,m gald skilled person like you can fix this classic.

Hi, How is the bike now? I don't want to pay too much for an ebike since I'm not going a far distance, but I don't want the motor or battery failing on me within months. Cheers!

Use a basic pulsegen or AWG. Adjust the slope, width and amplitude of a repetitive pulse to discover and test NB function, and then make tweaks if necessary. Back in the good ol days I significantly modified the NB circuit in the R71A this way; scope and pulsegen.

I've got the perfect environment for testing a noise blanker - it's the whole neighborhood. Last thing I need to do is make more noise! Nice fix, Nick.

No HF antenna? Inconceivable, Nick! Thanks, enjoyed the fix. Great result on the replacement switches.

Nick! The patience required to undo all those and put them back. No, I don't want to work on one of those. Well done.

MS1307 is IRF520N

I remember that budget 1402 mixer. Used one in the remote broadcast trailer for special events (State Fair, Park Concerts, Art Festivals etc). Surprised no spilled coffee, soda, or beer inside of it. Never had to dis-assemble one thank you very much Nick. Glad you got it working. Thieves broke into that trailer at night, while parked at the studio back lot, and stole everything they could, including Electro Voice RE20 mic's, Denon 951FA CD's, Telos and Comrex telco interfaces, and a 15KW Honda generator which was bolted near the hitch area. Sad Saxophone sound effect goes here.

Nick, that was an insane number of screws, knobs, nuts, washers...that's a well-built mixer but holy sh!t that's a *lot of work* for one fader swap! On top of that, the overhead of filming it, appreciate the edits. Nicely done. (Edit: PS nice job on the DC supply addition, too)

Great Video As Always Nick Regards mike.👹

I had to chuckle Nick - yours is a lot bigger than Manuel's (@electronicsoldandnew). 🤣

I tried a few diferent firmwheres and went back to the latest Quansheng one, if it will not TX on the HF band there is no point for me??

A good result Nick. There's so much interference around these days - I wondered why my own MSF driven clock wasn't updating any more and it turned out to be my pond pump. 🤯

It's a conspiracy Nick - they shut off the MSF signal as soon as you pop in the lab to test the receiver! Same thing happens if I ever want to test some solar panels - weather turns from a bright sunny day to overcast as soon as I step outside. The 60 kHz receiver board (5V) I bought is from an outfit once called "Universal Solder" but now called "Canaduino". They'll sell it with a 77 kHz crystal, too. It's reasonably easy to hook up the receiver board to a small Arduino board and decode the PWM BCD data into time for a 7-segment LED display; quite a bit smaller overall than the Old School but Very Cool Z80 solution. There are also older CPU-less solutions which clock in and buffer the BCD coded time directly to the display. Big boards, beautiful fascinating things, lots of shift registers. The Canaduino board does quite well here, even in the Faraday Cave, but I'm only 60 miles from WWVB. They better not move the transmitter! They did threaten to shut it down a few years ago. That's an impressive rod you've got there. :^) Great result! Loved it.

Have one range 250 meters

Please dont update it you can no longer revert!

i think your marco pierre white becaue you sound like him

Great video subbed

What an excellent video. Thanks for making it!

Gretas Job Mr. Ptronix . Please Keep Future More Video . Do you Are The Best.

Really thank you for this subject. i'm trying to make an oscillator/bandpass-filter for LCR meter.

I purchased, a Kenwood TS 2000X, from one of the U.K. emporiums second hand, about 2 years ago. It was originally purchased, as a backup for my Icom 9700 for 23cm fm / ssb. It’s probably worth mentioning, like many others, I came back into amateur radio after a very long break, but rekindled the interest during Covid, around 2020. I also checked / adjusted the tcxo / frequency, and yes it was very finicky and fiddly, but once done, was pretty accurate (allowing a couple of hours switch on before carrying out the adjustment(s) of course). The TS 2000X tends to get used a lot more than the 9700. Why? Because it is an absolute pleasure to use. Sensitivity doesn’t appear to be an issue, it hears as well as any other 2m / 70cm / 23cm radio I have in the shack. Also, the TS 2000X doesn’t need any additional frequency stabilisation, unlike the Icom 9700. The 9700 required the addition of a Leo Bodnar, gps signal injection mod to make it anywhere near usable on 23cm ssb. Not great for a radio that only needs to concentrate on just three bands, and the right side of £2000, an issue that Icom have never really fully addressed. Sadly, Kenwood have never made the modern replacement, of the TS 2000 that many of the main emporiums suggest they might (I don’t believe they know anyway). Equally as sad, the TS 2000 in all its guises, are becoming rarer to find as time passes by.

Loved this, Nick, thank you, have always been fascinated by these. Heard the theme to Mission:Impossible while watching!

Ok Nick, it's much much greener there, much more traffic than I expected. Hilly here too but it comes in steep waves rather than one long hill - brutal on the mountain bike. One good thing is that it's almost all downhill on the way back home. No cows. Occasional horse. Funny, but they weren't that steep when we moved here. Gravity has increased a bit, too.

You need to use a calculator to work out simple powers of two? Good grief. Did you not go to junior school and learn your times tables?

hi, can you please indicate where to find the article describing the oscillator? Thank you.

Do a barrel roll!!!!

Absolutely effing brilliant, Nick! Must be a low pass filter of a sort on the sensor electronics to cope with noise etc, plus the manufacturer made a reasonable bet that you won't go much faster than 60mph on that bike!

Hello, since you say that they are brand new in the box but have mould on the dust cap I reckon that there is corrosion on the coil. I've seen it before where moisture has built up a layer of 'salt' on the voice coil.

Thanks! The 640a v.2 is rated at 75W per channel but the original is rated at 65W so this one looks to be be in spec.

I''ve watched so many Quensheng videos recently it's hard to keep track of who said what.... re transmitting on bands outside of designed range - known to put out crap amount of watts where you want them & leak the rest in harmonics & spurious emissions. re programming 27mHZ via Chirp - also known not to record any frequency below 50 (but will still record other details)... so you could put all your channels in, name them - yup, they'll all be 50mHZ, but then you can manually edit them to the correct frequency. The Chirp bit will take you 5 minutes, but prolly about 1/2 hour to manually re-edit the frequencies to what they should be. So, unless you really want the Quensheng for listening to CB (which is sadly where I find myself), prolly not worth worrying about.

I bout to make it.can you share the schematic of the amplifier circuit?

Audio is quite clear with the Sonicake (great name!), treble end sharp but not too sharp. That's great that the lamp assembly has power regulation in it. Thought that was a neat job especially in a box so crowded with wires. Extra points for the mention of Glasslinger and the fact that absolutely nothing caught fire. Always a good result!

To get a scope to show a stable AM display, use the sync out on the audio sig gen (if it has one) to trigger the scope. Or adjusting "hold off" on the scope will also give a stable display.

That's an expensive bike Nick. I looked it up. Don't give up on pedaling around, it's still the most cost effective. Couple rides here in Spring, not much since because of temps. Curious: The failed display looks like traditional Grey LCD. What is the Blue display method? LCD displays don't tolerate extreme heat or cold well (personal experience)