Digital clock

[Radio Fixer]

Wow! those Metcal soldering irons / stations are a lot of money. Not really needed for valve radio restoration IMHO. But maybe they come into there own for PCB work.

For radios I use a 60W Weller and prefer the mains ones to the low voltage transformer type. When I do PCBs, not often these days, I have a Maplin Xformer type that has variable temperature control and takes a very fine pencil bit.

In store are lot of other irons of different wattage and sometimes really useful is a 200W Weller with a big spade bit. Cant be beat for unsoldering / soldering braids from tuning gangs.

Gary

[Skywave]

Wow! those Metcal soldering irons / stations are a lot of money. Not really needed for valve radio restoration IMHO.

. . . sometimes really useful is a 200W Weller with a big spade bit. Can't be beat for unsoldering / soldering braids from tuning gangs.

I find that my Metcal - when fitted with a ¼" chisel bit - is quite adequate for that job.

Al.

[Nick]

I find that my Metcal - when fitted with a ¼" chisel bit - is quite adequate for that job.

Ditto. Love them. Not found an electrical/electronic task that they can handle with ease.

However, without a doubt they come into their own for fine work - their control is phenomenal and they are extremely light as they use RF to heat and control the pen.

I bought mine from a lab closure in the US - then converted them for UK usage. (just changing a few links inside).

The MX-500s are the later version of the STSS-series. The MX-500s (40W max) have in turn been superseded by the MX-5200s (80W max). Just to confuse the issue, OK International (who own Metcal) have re-introduced a new range also called MX-500 which are essentially the old ones with micro-processor rather than analogue control. Even though the wattages may seem on the low side, the energy is delivered with such accuracy over a very controlled area that I've never felt that the pens are under-powered.

As a system for soldering, desoldering and re-work, especially for very fine work - I do mainly SMD stuff down to 0402 (1mm x 0.5mm component size) and chips with pins less then 0.5mm apart - Metcal is the industry standard.

[Radio Fixer]

"unsoldering / soldering braids from tuning gangs." Not properly worded by me, it should say : braids from the chassis from tuning gangs. Find it hard to imagine that a 40W iron can do it from a large metal chassis. A 60W Weller wont do it. But if you say so.

Well I have only ever soldered one SMD and did it with the Maplin and fine tipped bit. Not ideal, I agree.

cheers Gary

[Nick]

You are correct in that its a slow-ish process for heavy stuff but it does work - I often pre-heat larger lumps to speed things up...

Currently I'm designing a board around a micro-processor in a 48VQFN package - 48 pins on a 7mm x 7mm chip (including leads) - pin centres are 0.5mm apart and each pin 0.25mm wide, so pin separation is 0.25mm.

You easily do this sort of stuff with Metcal kit, but in this case I'll also be using a laser-cut mylar solder stencil and paste...

A 200W gas iron might be a little severe...

[Skywave]

Indeed, there are the rare occasions when I resort to using my 200-watt iron. But compared to a Metcal with a wide bit, the following differences encountered during such a soldering operation are:

1. The 200-watt iron is much heavier than the Metcal; the 200-watt iron is much bulkier than the Metcal. Hence, the Metcal is far easier to use for a given 'heavyweight' soldering operation and more precise control is possible to determine just where the heat flows.
2. By definition, a 40-watt Metcal will use less electricity than a 200-watt iron. (Agreed, this is a debatably minor issue).
3. A 200-watt iron can easily cause nasty accidents, including burns to your fingers, etc., and various non-human parts. With a 40-watt iron that uses any technology, those risks are substantially reduced.
4. A conventionally-heated 200-watt iron with its huge copper bit will occasionally require that bit to be filed to ensure an even flow of heat. This re-forming of the bit is not applicable to a Metcal.
5. There is a huge range of bits of different types & shapes for a Metcal. (More than any other iron that I know of). That provides maximum versatility in any iron, from precise soldering to heavyweight tasks.

However, the downside to owning a Metcal are:
1. Initial cost of acquisition. (Mind you, Weller TCP 'soldering stations' aren't particularly cheap, either!)
2. Cost of replacement elements. (And Weller TCP parts are not cheap either).
3. The control unit for a Metcal is complex; there is no control unit for a conventional iron. Therefore, one would expect the long-term reliability of a conventional iron to be greater. But I have owned my Metcal control unit for several years now without any failures within it. (For the same period, I have had to make several repairs to my two Weller TCP irons).
3. A Metcal uses R.F heating: mine puts out several strong signal in VHF Band 2. Fortunately, those 'signals' do not clash with stations I listen to. But I do not know the other freqs. it generates - and radiates. However, that unwanted radiation from my Metcal does not cause me any problems: it's a trivial issue.

The main difference between any conventional iron (including irons like the Weller TCP) and a Metcal is that the Metcal uses R.F heating. That approach - together with its control unit - ensures that the rate of flow of heat is not determined solely by the heat capacity of the bit. If the workpiece demands more heat, the Metcal iron controller simply says "O.K.: I've got that request: here it comes!" A conventional 'open-loop control' iron can't do that. And R.F heating is much more efficient at supplying that demand than by conventional methodology. And even a temperature-controlled iron like the Weller doesn't cope very well with heavyweight soldering, in comparison.

My conclusions.
Simply have several soldering irons available - including a Metcal. Then you can choose the appropriate iron (plus bit) for any given task - based on personal experience. For me, my Metcal is my 'everyday' iron - but that is simply a reflection of the type of soldering that I generally do.

Al.

[Mark Hennessy]

Metcal uses do seem to be rather evangelical

For the sake of balance...

I use Weller TCP. In the past, I have worked in places that used Metcal and Weller TCP. At the time, I thought that both were nice - both were good at big and small stuff with the right tips, both had good temperature regulation, and the results I could achieve with either were equally good. Now, this was 20 years ago, with better eyes than today, and surface-mount stuff wasn't as small as today, but I today I don't do anything on a smaller scale, so the comparison is perfectly valid for my needs.

A brand new Weller TCP iron and PSU comes in at around £150. Of course, they go second-hand for a fraction of that. You can DIY the PSU as it's just a transformer, of course. A new element is about £30. The switches in the older irons could be unreliable, but I can't remember the last time I changed one - they are a little over £30 when needed.

I'm no expert on the Metcal range, but the MFR-1110 - which seems to be the entry level - starts at £240. And that's a re-branded Oki, by all accounts. The MX500 range seems to start at £575. And a quick search of Farnell didn't show up any spare parts for these models. Hmm...

I have only had one TCP fail in nearly 30 years of using them. This was about 15 years back, and I dread to think how old the iron was at that point. As it was so old, I just brought a new iron - I remember it cost £45 at that time. However, since that experience - it's horrible to be without - I have bought a few more second-hand. They are so cheap that it's no extravagance to have them standing by with a range of different tips fitted, ready for different jobs. No need to swap the tips (easy enough, of course) - just plug in the required iron and in 30 seconds get going...

At work today, as well as the TCP units, we have some of the electronically controlled units (an earlier version of the WSD series, IIRC). These are also very nice - around £250. But in use, I get perfect results with TCP, and don't feel the need to change. The TCP idea has proven to be elegant, simple, reliable and cheap. No semiconductors or software involved. What's not to like?

Of course, that's not to say that I wouldn't be delighted to have a WSD or an MX500 if someone offered it at the right price. But the TCP is not the compromise that a lot of Metcal users would suggest. Just go searching some of the other electronics forums to see examples of "rabid fanboys" in action

Now, with all that said, I assume that the mains-powered 200W Weller mentioned earlier is not temperature controlled? Sadly, non-controlled irons are definitely a mixed bag - ever tried strapping a thermocouple to one? They have their occasional uses, but it's true that a ~50 watt temperature controlled iron can do the work of a ~200W non-controlled iron. For day-to-day work, a controlled iron is much better tool in just about every regard. By "controlled", I mean with sensing and feedback, not a variac or light-dimmer (which is what the cheap "controlled" irons use). I use my TCP for delicate PCB work and restoring Hacker Mayflowers, and would highly recommend it to those who have standard non-controlled irons - you won't look back. Just don't be put off my those who tell you that you need to stretch to a Metcal - in terms of performance, it's a bit like deciding between Audi and BMW when your current car is a Lada

[Nick]

Metcal uses do seem to be rather evangelical

They're just very very good - the market speaks volumes

I also have a Weller and an Antex for rough-n-tumble jobs, but once you've done fine work with a Metcal pen... sigh....

Being fair, the original MX-500s (the ones I use) use ordinary PTH components and the annotated schematics are readily available - none of the components are "exotic" - they're all off-the-shelf - the one repair I've had to do (one of the base stations stopped doing "auto turnoff") took all of about 10 minutes.

When setting these beasts up, you are supposed to use an in-line RF meter (my bases came with one) to make sure the RF power management is properly aligned - they are also inherently static-safe. I haven't had to re-align my units (I have two) for at least 5 years now.

Yup - they are expensive, but there are good reasons for that

[Mark Hennessy]

Here we go

As I said, I have used Weller TCP and Metcal for fine work (and "big" stuff). I got first-grade results with both. Neither stood out as being obviously "better" in use. When you factor in price and support, it's a no-brainer.

If I was spending Metcal-money today, I'd want something with adjustable temperature, which rules out Metcal as far as I can tell. In addition to Weller, I'd consider Pace and JBC. But before moving from Weller, I'd need to be convinced of the support, and I'd want to see prices for all spare parts.

Fundamentally, I'm all for persuading people of the benefits of a properly controlled iron, and a Weller TCP is a good bet - a simple, well-proven, well-supported product for a fair price new, and a safe bet second-hand. There is a quantum-leap in performance between one of these and a basic non-controlled Antex or whatever. But performance differences between a TCP and a Metcal are small-to-negligible for most users, most of the time.

The trouble with these sorts of debates is that people who might be half-interested in stepping up from a basic non-controlled iron become trapped into believing that only a £600 Metcal will do, and therefore will be put off from making the step to a TCP or similar.

[Nick]

Here we go

Heh

I only use Metcal because I'm doing most very fine SMT work (as I mentioned above). For almost every single amateur (and a lot of professionals too), Metcals are not necessary - businesses will amortise the cost over three years anyway, so aren't bothered.

BTW., they do have temperature control - its built into the RF characteristics of the tip - the tips are preset for different temperatures - you buy tips based on both their temperature and shape - the temperature is generally set to whatever solder mix you are using, normally a SAC alloy at about 220C - this is 37C higher than the old 63/37 SnPb eutectic mix (183C), so the move to RoHS meant that all commercial shops had to renew their bits.... not to mention everyone having to have higher-temperature-resistant components so that they survive flow and IR soldering...

I have a couple of 100 tips - bought a job lot about 10 years ago for peanuts when a lot of labs were closing - I fully agree that to buy new, they're not cheap. Annoyingly, they are all pre-RoHS, so I've had to buy some new ones to re-work modern SAC-soldered boards.

Metcal also have a full service center in the UK - spares are available on eBay and elsewhere as well.

Nuff of all this! Each to their own