Recent Posts

1

RF, Microwave, Ham Radio / Re: Poor performance of DIY SMA-M Precision Load

« Last post by Randy222 on Today at 10:20:43 pm »

Just a side question.
With the level of  wanted "precision" in this DIY config, I wonder if some form of DIY laser diode spot welder, or resistance welding, would help?

2

Thermal Imaging / Re: Using Xtherm/Infiray smartphone cameras as Webcam

« Last post by michaelnyden on Today at 10:18:41 pm »

Thanks for trying guys but nothing I can find on github appears to work, at least not with the T2 pro.

3

Microcontrollers / Re: STM 32F4: any way to make it self program its FLASH from an external SPI FLASH?

« Last post by peter-h on Today at 10:17:26 pm »

Yes; I forgot. This came up in that "breaking RDP2" thread, where the VCC pulsing method was used to execute the memory read command in the boot loader.

4

Test Equipment / Re: (Old) Hioki 7010 DC Signal Source - Any information? Schematics?

« Last post by kblue on Today at 10:16:01 pm »

Hello again!

No luck after changing the caps. Most of them also measured completely fine. Guess without schematics or something similar, this will be on hold for a long time. (possible eternity)

Best wishes!

5

Test Equipment / HP 3721A Correlator exposed

« Last post by dazz1 on Today at 10:15:05 pm »

Hi
I opened up the HP 3721A today to do a visual check and clean as required.  No sign of any repairs or charred parts.
It only had a thin layer of dust, so used, but not excessively.

All of the PCBs are gold plated.  None of that crappy solder mask or conformal coating stuff.

All the knobs and lamps work. 
I have not yet applied any signals so I don't yet know if it is functional.
The CRT is better than seen in the photos.  It is razor sharp.
The vertical on the trace is unsteady and vertical varies with intensity, so probably a developing power supply fault there to fix (a new repair thread). 

The 50 pin digital I/O port preceded GPIB and was designed to connect to the early HP computers.  All comms is controlled via hard wired logic in the HP 3721A. 

6

RF, Microwave, Ham Radio / Re: Poor performance of DIY SMA-M Precision Load

« Last post by Randy222 on Today at 10:10:16 pm »

The most beautiful SMD resistors I ever soldered were Vishay Sfernice CH series flip-chip 0603 resistors that my customer had specified by mistake, not realizing they weren’t in the signal path and thus didn’t need to be high-performance ones like those. They’re beautiful little white cubes that cost about $6 each. But they’re good to 50GHz, which is something an ordinary 0603 resistor can’t claim!

0603, rated 400mW. Wow, it's a tiny package for 400mW (68 x 33 thou.in.), I wonder how hot it gets at 400mW in open air.

7

General Technical Chat / Re: Invention of the day: The USBottle

« Last post by SiliconWizard on Today at 10:08:48 pm »

Probably.

8

Repair / Re: PLD getting hot

« Last post by fzabkar on Today at 10:06:32 pm »

VR1, VR2, VR3, VR4, VR5 are 5 linear power supplies (+/- 5V, +/-8V, +3.3V).

9

RF, Microwave, Ham Radio / Re: CB and Ham Radio Techs Love Their Bird Wattmeters

« Last post by metrologist on Today at 10:06:02 pm »

...  If it does have a PC interface, hopefully it can update faster than 1Hz.

I'm a little lazy now to look into the details. The brochure posted later indicates a measurement time of 180 ms, in the golden 2W deadkey, 20W swing range into your heater.

I'm not sure how you would spec bar graph speed, but the NRT2 bar graph is very, very fast compared to anything else I've seen.

Fast as fast might not be fast enough. I would expect it to be faster than the measurement time.

From a previous post, showing update rate of a Coaxial Dynamics vs early version of my homemade meter.

joeqsmith for President....of wattmeter product design and marketing. 

10

Test Equipment / Re: HP 8566B Debug/Rebuild

« Last post by MarshallPlexi on Today at 10:04:25 pm »

Great stuff Kean! I watched all of this and will tear into the attenuators tonight and see if I can find anything obvious.