Why should someone replace ALL the capacitors on old Tube equipment?

Bingo: That's it except the one we were using was the PCB mounted model, something like the 620PC model: Curtis Instruments is still around. The mercury coulometer product does not appear on their web site, but is mentioned in the company history at:

Thanks much.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Skype: JeffLiebermann     AE6KS    831-336-2558

More:

Mercury coulometer:

Patents galore:

-- Jeff Liebermann snipped-for-privacy@cruzio.com

150 Felker St #D Santa Cruz CA 95060 Skype: JeffLiebermann AE6KS 831-336-2558

Many of the newer radios are starting to use electronic circuits or more likely software fro the filtering now.

Many newer radios do not have much RF circuity in them, mainly microprocessors doing most of the work. This trend started about a dozen years ago and is progressing more and more every year. Instead of being limiated to just 2 or 3 filters (that often cost around $ 100 each) you just turn a knob or move the mouse and set up any type of filtering you want.

You're welcome. I have heard they stopped making them, after some old ones caught on fire and did a lot of damage.

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)

I was involved in the development of the first successful DSP based Telemetry receiver. It was the Microdyne RCB2000, which was around $80K for a completely software configured dual diversity receiving system. It went from RF to a 50 to 90 MHz analog IF, followed by the DSP, and multiple FIR filters for the IF and Video systems. This was back in

2000-2001. The success of that product caused L3com to purchase Microdyne, since their DSP based design never worked.

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)

I don't see what might have burned. They were very low power. According to the data sheet, 4uA at 5V for the model 120PC. My guess(tm) is that the mercury used in the indicator was deemed environmentally incorrect.

It would interesting to resurrect the idea, but using something less hazardous, in order to build a warranty timer. Offering a warranty by hours of use, instead of years after manufacture, would be an attractive sales gimmick.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

It was the AC versions that were reported to have caught fire, just like some of the modular IEC power connector/line filters when the European made film capacitors failed. Certain brands of these modules are replaced in every piece of equipment by some people who collect old test equipment.

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)

The weaknesses are intermodulation due to insufficient RF band-pass filtering, and quantization noise due to insufficient resolution in the A/D converters. RTL2832 has ENOB of around 7... hopeless.

There's no escaping the need for a proper RF front-end for any serious work.

So long as there is nothing 100KHz away from your desired signal, and no two signals spaced 50KHz apart that intermodulate in your RF front end. Imaging is a killer. Double conversion can help, but nothing beats RF selectivity.

Some of the modern receivers are taking advantage of the availability of devices with much better linearity and headroom, which reduces the intermod - and they're using I/Q conversion to defeat imaging - but they cannot achieve the performance of a good communications receiver.

Software hacks love SDR because it makes them feel like RF experts, but they're not.

Clifford Heath

Sorry, but that sentence is not English, and I have no idea what you mean.

So do I. They can be remarkably good, but not "amazing" in any sense.

That's now at least a year old, maybe two. They'd continue to sell what they had in stock, but that was it.

I think I mentioned that some Japanese company was making mechanical filters in the sixties (word is that they had some foam in them that goes bad over the decades), which showed up in Lafayette ham receivers and CB sets, but for some reason, that didn't continue to be a source of mechanical filters.

There wsa an article in CQ magazine in the early sixties where someone described a receiver they built, and they even built the mechanical filter. Not sure if they gave enough information to duplicate the filter at home, or if anything too out of the ordinary was needed.

I think ceramic filters took care of the cheap mechanical filters, leaving COllins for the really good receivers.

Michael

That's why in the past, some receivers went down to a 50KHz IF, if you wanted a selection of filters, it was cheaper using LC circuits down there than a bunch of crystal or mechanical filters at some higher frequency.

It is amazing. Even the low end shortwave portables are using ICs that do a bit of RF handling, and then down to where it can convert to digital. SO you have ICs that offer more than a given receiver provides, the modification now consisting of changing the firmware, or bypassing the internal microprocessor, and controlling it through another computer.

And of course the high end receivers are going the same way, except they use better circuitry. Build the circuit once, and then you can do endless things like changing selectivity or adding different types of demodulators.

Michael

Have you tried Software Defined Radio? Free software and under $10 for the USB based hardware will get you started.

DVB-T-DAB-FM-RTL2832U-R820T-Tuner-Mini-USB-RTL-SDR-ADS-B-Receiver-Stick-DH-/

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)

I have been playing with them for about 2 years. They seem to work very well and depending on the one you actually use, they go from about 25 MHz to 2 GHz. The sensitivity for them is about 1/2 of a microvolt for FM. The things that can be done and free software is amazing to me.

The do all the common modes of ssb, am,fm, cw, and some other things such as decoding pagers and even the transponders on airplanes.

Here is a link to some more info on them.

Look for some software called sd sharp while you are at it.

That is the software that I'm using, and I've had the hardware since

2014. :)

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)

Or for good RF test equipment to design and build it. I replaced my old Boonton 42B and 92B analog meters with their 4200B and 9200A digital meters. I also have a Fluke 8920A digital True RMS meter that works to

20 MHz. This is some of the same type of equipment that I used on the production floor at Microdyne.

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)

Are mixing the $ 10 dongles and real communication receivers that use microprocessors instead of the crystal and mechanical filters ?

I have a ham transceiver that uses the microprocessor instead of fixed filters. I can assure you that it will seperate signals that are within a KHz or less without any problems.

And nobody was dropping from HF to 50KHz, except in the very early days of the superhet. SOme of the receivers were modern enough that they had a "roofing filter" in the HF range or even above it.

There's nothing magic about using phasing to do conversion and getting rid of the image. It was certainly talked about in microwave circles fifty years back. But nobody seemed to apply it to low frequencies, though the RF phasing network probably put some limits on it. But most hobbyists thought in terms of the phasing method for generating SSB, and were unable to make the leap to downconversion.

The Drake R8, did it come out about 2000? used the phasing method to go from an IF around 45MHz, straight down to 50KHz. Yes, the ultimate selectivity wasn't right after the first mixer, but you weren't likely to get an SSB-width filter at 45MHz either, so you'd still need to downcovernt

I'm more interested in a hybrid, the variable selectivity and ability to do different types of demodulation, rather than a magic IC that pretends traditional RF issues are no longer a problem.

Michael

They were good when they were first introduced, but the plastic casings didn't hold up to their long life hype. If you look at a Black Beauty, they soldered the leads to the tubes used to fill the housing with PCB based transformer oil. That sealed the housing but the molded plastic appeared to be incompatible with the oil used. The construction was detailed in some early ads for the Black Beauties.

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)