Marconi Collectors

[Sinewave]

Originally Posted by Lloyd 1985

They have done it twice now, and I wasn’t the only person showing my disgust!

Regards
Lloyd

They sound like a lovely company to work for.

The company I work for are renewing all of the IT equipment, desktop PCs, servers, even those really nice all in one Lenovo Pc's. The IT guy said "it's going in a a WEEE skip anyway, so take what you want".

[Andrewausfa]

Originally Posted by Sinewave

• TF995
• TF995A/2M
• TF995A/3/S

Are you including the Signal Generator No.18 CT402 as the TF995A/3/S?

I would like to know the differences. Does S mean 'Services', M for 'Marine'? I only ask that as my B/2M (one to add to your list) came from Marconi Marine. The B/2M has a low frequency 'start' of 200kHz.

Andrew

[Sinewave]

Originally Posted by Andrewausfa

Are you including the Signal Generator No.18 CT402 as the TF995A/3/S?

I would like to know the differences. Does S mean 'Services', M for 'Marine'? I only ask that as my B/2M (one to add to your list) came from Marconi Marine. The B/2M has a low frequency 'start' of 200kHz.

Andrew

In my collection I do, as my TF995A/3/S is in a military rack case and has No.18 CT402 and TF995A/3/S written on it.

[G0HZU_JMR]

I've still got a few items of RF test gear made by Marconi although they rarely see any use these days.

2015 sig gen
2019 sig gen
2019A sig gen
2022C sig gen
2024 sig gen
TF2430 frequency counter

Only the 2024 sig gen sees regular use, the rest sulk in a storage room along with the rest of my old (retired) test gear...

[Skywave]

Originally Posted by Lloyd 1985

We still have a load of Marconi test gear in daily use where I work! RF power meters (digital ones), some large early digital signal generators, some sort of network analyzer.. sadly a massive load got skipped last year, and we were not allowed any of it

Could be where the company is exercising its H & S obligations.

Two scenarios:

First: they offer it to you, F.O.C. You take it home (or somewhere not under the company's jurisdiction), power it up - and for one reason or another, someone gets hurt - or worse. The company could be held liable.

Second: as above, but you simply 'help yourself' to it from the skip. Apart from the fact that doing so without the company's permission constitutes theft, the scenario above, where someone (or more) got hurt, will still apply - and the legal consequences will probably be similar.

Yes, I know that when companies do things like this, it can be truly heart-breaking. However, you can always ask - and they might want you to sign some sort of 'disclaimer' to cover their corporate *** just 'in case' . . .

These days, 'litigation, fear of' seems to be an almost knee-jerk reaction to almost anything that just might.

Al.

[mole42uk]

Originally Posted by Sinewave

They sound like a lovely company to work for.

The company I work for <snip>"it's going in a a WEEE skip anyway, so take what you want".

A pal used to work for a national telecoms company, who used to hold regular "yard sales" of redundant equipment where you just went in, picked up the gear you wanted and walked out. Until the day someone got the piece of kit home and cut themselves on it. And then put a in claim to the company for damages. And won the claim.
Now all the redundant equipment gets shredded, always.

[Granitehill]

I've got a TF2503 power meter and a TF2008 signal generator. Both in regular use - the TF2008 is powered up most of the time and has just about every capability I ever use. Only used the sweep facility once, though. Downside - heavy and a bit of a sod to work on. Some of the modules are pretty difficult to get at despite hinged sub-units.

The TF2503 is a lovely piece of kit, and possibly the best of its kind ever (Makes Bird's products look a bit mundane). I don't think many were sold, though, as it cost £493 in 1968 !
It's based on in-house custom designed components - a thin film precision thermocouple, and a conical thin film load resistor immersed in a fluorocarbon coolant. Marconi also sold a much cheaper power meter with similar ranges (o-30W, 0-100W), but the 2503 covers 0-1GHz with a vswr of <1.1:1.

Anybody know what the target market might have been? Setting up low power TV transmitters, perhaps?

[avocollector]

After the avos and heathkit gear I love Marconi stuff but sadly I'm a bit too far away to take advantage of any UK offers. Have 2 of their sig gens - one seemingly from the ark weights 30kg and with really hefty rf output - it 'bit' me one day in a moment's inatention putting my hand too near the output lead!

[Radio Wrangler]

Originally Posted by Granitehill

The TF2503 is a lovely piece of kit, and possibly the best of its kind ever (Makes Bird's products look a bit mundane). I don't think many were sold, though, as it cost £493 in 1968 !
It's based on in-house custom designed components - a thin film precision thermocouple, and a conical thin film load resistor immersed in a fluorocarbon coolant. Marconi also sold a much cheaper power meter with similar ranges (o-30W, 0-100W), but the 2503 covers 0-1GHz with a vswr of <1.1:1.

Anybody know what the target market might have been? Setting up low power TV transmitters, perhaps?

There are several sorts of RF power meter.

The Bird 43 and its ilk are intended to be rugged units, bounced around in the backs of vans and used to set up transmitters in the field Turning the slug backwards reads reverse power so you can check antennae are tuned correctly. The slugs available suit common transmitter power levels and bands.

Then there are precision power meters designed for lab use and standards lab use. If you're designing a transmitter for a critical application where there are legal or contractual requirements to reach a guaranteed power level, then you have to account for the inaccuracies of your power metering. If your power meter is only good to +/-20% then you have to engineer the transmitters to be 20% more powerful so you can be sure your tests that indicate a pass were valid. This puts up the power demand of the transmitter and will likely move you close to failing a power consumption spec. Buy a better power meter and the uncertainty drops and you get some margin in your specifications of your transmitter.

In standards labs you get a posher still level of power meters. RF power is difficult to measure with accuracies any better than a few percent. In this group you'll find the HP 432A which is a precision DC-substitution power meter They date back to the sixties and are still in use today, usually driving a pair of 6-digit DVMs in an automated setup. Some folk from the National Physical Laboratory were visiting our plant to discuss noise source calibration and I gave them a plant tour. They spotted 432As on their production line and made strong appeals to not stop making them! There is a higher precision design, the Type IV power meter by NIST the US standards people, but they're hard to find and rather expensive... they use the same heads as the 432A. These sorts of machines measure only up to 10mW. If you need to measure more, you need an accurately calibrated attenuator

HP did stop the old 432A, though, but they had to do a newer version of the DC substitution head and meter to fit in with their current product line.

These things get used to calibrate precision test equipment.

One thing to beware of is badge engineering. Various companies have taken over each other, others have sold other firms power meters rebadged, so sometimes it can be a bit of a game working out who made whatever is in front of you. There are also less precise heads that aren't DC transfer standards, and even less precise simple thermal ones that gauge power by the temperature rise of a resistor.

HP became Agilent Technologies, and is currently Keysight... don't know what they'll be called next!

David

[Granitehill]

The TF2705 seems to have been the final development of the load/thermal type of instrument as used for higher powers at HF and VHF, but not in the same precision or cost bracket as the HP bolometric devices. The Bird devices I refer to (not the 43 vswr/power meter) were metered high power loads. The earlier Marconi competitors like the TF2512 were cheaper than Bird, but I wonder if the TF2705 was an attempt to compete head-on or out-spec the Bird. (The TF2705 is quoted as 5% accurate all the way to 1 GHz).

I remember the HP432A - used in considerable numbers in BT microwave stations. I liked them - I remember being able to trust them in a way I didn't with the rather drifty HP430 and 431 predecessors. The last I remember was the HP435A - again excellent. BT then started buying Marconi power meters instead (cheaper than HP?), but they were indeed badged - they were made by General Microwave Corp. I guess this was when Marconi were starting to be hit hard by the competition, and pressure was on profit margins.