Recent Posts

21

Buy/Sell/Wanted / Band 1 Stereo FM Link Broadcast Warehouse TX25 Transmitter + Receiver

« Last post by kloss on Today at 04:25:40 pm »

Band 1 Stereo FM Link Broadcast Warehouse TX25 Transmitter + Professionally adapted Stereo Receiver

TX25 is the full bandwidth version capable of any Band 1 broadcast channel

Receiver is XTAL controlled currently on 52.75 MHz some alternatives available from stock if required

Tested working, 1 owner from new these always gave great results

The transmitter and receiver both offer MPX Composite support

A new SBS Stereo Audio Limiter may be included free of charge on request

Any questions - let me know

£1000 Collection or shipping available

22

Buy/Sell/Wanted / FS: ENI 403LA wideband RF amplifier 3 Watts 37dB 150 kHz - 300 MHz

« Last post by kloss on Today at 04:23:43 pm »

ENI 403LA Class A wideband RF amplifier 3 Watts 37dB 150 kHz - 300 MHz

Tested in good working order (photos available)

Power cable fitted with IEC type connector to support variable length cables

£200 Collection or shipping available

23

Beginners / Re: Bulk input caps and impedance

« Last post by Zero999 on Today at 04:22:41 pm »

Now I want to try what an inductor does.

10uH torroid ... not what I expected.
470uH - more what I expected, although it appears to only delay the steep portion of the rise.
4.7mH and it's much better.... longer / smoother / lower gradient.

What's the catch?

What's the ESR of those inductors?

How do they compare to a resistor of the same value?

24

Programming / Re: Linux Dependency Black Hole

« Last post by mag_therm on Today at 04:22:08 pm »

Hi tatel, That is interesting.
Yes I have downloaded the firmware  C files from git  and have been examining them. But I dont have C IDE or debug, (And not used C for 36 years, so a lot to learn)
So thought MCUX and a devel board  would give me everything including debug.

Also I have been thinking today, with the ease of uploading the firmware, and as I only need < 10 frequencies I could just build 10 firmwares each with a fixed dataset for the Si5351.
A little UI and bash to replace firmware on frequency change , and with the latest Gnuradio ( python based)  which allows users to build their own DSP,     could be an easy solution at least initially

25

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by Fungus on Today at 04:21:43 pm »

1) oscilloscope is not properly BW limited, so Sinc filter is unable to reconstruct perfectly, instead of nice sine, it creates AM sine.

140MHz is below Nyquist.

26

Buy/Sell/Wanted / FS: ENI 403L wideband class A linear amplifier 150 kHz ~ 250 MHz low O/P fault

« Last post by kloss on Today at 04:21:14 pm »

ENI 403L wideband class A linear amplifier 150 kHz ~ 250 MHz, designed to give up to 3W output.

Showing low RF output. All discrete component design so should be an easy repair.

£125 Collection or shipping available

27

Programming / Re: Linux Dependency Black Hole

« Last post by tatel on Today at 04:18:26 pm »

Another thing, developing tools, libraries, etc, take a big chunk of hard disk space, so you could find your Pi doesn't have that much space available. You could perhaps add some hardware, or do the development on a regular PC. In that case you would be creating binaries for an architecture in a machine with another, different architecture. To do that, you should look at "cross-compiling"

It basically means you first built a toolchain able to do what you want. That's usually how OpenWRT is built, and I'm pretty sure it will be the same for the Pi.

28

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by Mechatrommer on Today at 04:17:14 pm »

Riddle me this:
Signal theory also says there's only one curve that fits a set of sampled points in a bandwidth limited signal.
The "AM" signal fits perfectly so how can we say it's possible to reconstruct the original sine wave? It contradicts theory.

the possibility is i already mentioned...

1) oscilloscope is not properly BW limited, so Sinc filter is unable to reconstruct perfectly, instead of nice sine, it creates AM sine.
2) the filter probably assumes (algorithm used is for) "uniform sampling distance" where in reality is not.
3) or simply, DHO900 is not using proper Sinc filter? (if shapirus can provide me with CSV data of the sampled 142MHz @ 312.5MSps that produced the AM shape on DSO, i may try to replot it in my VisaDSO with its latest implementation of Sinc (internet open source copy pasted implementation) so we can see if same AM shape is produced)

https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem

maybe we can look the same test made by shapirus on SDS800X if scope can produce the same AM shaped signal very near to (but not reaching) Sr / 2. if SDS800X is properly BW limited and Sinc filter/interpolation is implemented correctly i suspect it will not create such AM shape, it should be nice 142MHz sine (constant amplitude on each cycle) unlike the picture you linked earlier (on Rigol DHO900) if sampled at slightly higher than 284MSps (such as 312.5MSps). ymmv.

29

General Technical Chat / Re: Is LinkedIn worth keeping?

« Last post by mendip_discovery on Today at 04:17:06 pm »

I go in there every now and then to just laugh at the corporate head shots they have. Some of course have cool pictures, as they are way too cool for school, you know picture of them and their midlife crisis.

EDIT: For a laugh, I logged in on a private tab, and within a few scrolls past the adverts, a message/bot popped up asking if I was looking for a job. Feck me it's 9 adverts and maybe an odd post by someone I know. Its really not worth it.

30

Buy/Sell/Wanted / FS: Cranage Plipman EMC Emissions tester 30 kHz ~ 30 MHz

« Last post by kloss on Today at 04:16:53 pm »

Cranage Plipman EMC Emissions tester

30 kHz ~ 30 MHz professional EMC emissions tester, portable in carry case with mains connection cable and charger.

Connect to either mains or RF input to monitor emissions either from the mains or from RF signals.

Photo available showing working, receiving BBC R4 LW from small indoor aerial (not included).

Calibration carried out last year so spot on frequency.

£200 Collection or shipping available