Hi Dave,
I've just edited that post to clarify the benefit of clicking the notify button as per the following.
To add to the above advice, that the key benefit to clicking the "Notify" button is that you can delete the tab any time thereafter and de-clutter the web browser. I usually wait a day or three to see how many times the attached images have been viewed before doing that, even longer if I think I may have more to add. If the viewed count rate drops right off after a week or three and I'm still planning on adding another post, I really aught to add it to my bookmarks folder and close the tab but I'm not that organised so just tend to leave the tab open.
As for the venerable FY6600, that proved to be a surprisingly excellent performer once you'd voided its warranty with several relatively trivial modifications to fix its seemingly beancounteritus inspired penny pinching induced shortcomings. Sure, the penny pinching did save a few cents on the dollar in production costs but I think the motivation to even risk such a ludicrously foolish penny pinching strategy was more to do with reducing their costs on handling warranty returns down to a nice fat zero by taunting their target market demographic into turning this Sow's Ear into a silken purse at the expense of a voided warranty.
I think Feeltech knew their target demographic far better than it knew itself and were maximising the PRC's government subsidies on export shipping costs to make any warranty return attempts a high risk exercise if the AWG had been 'fiddled with' in any way since the return shipping charges would be an upfront cost to the customer, only refunded if Feeltech deemed the warranty hadn't been voided.
When I'd offered this hypothesis to the group two or three years ago, it was discounted as just another "conspiracy theory" but the fact that their latest 6900 version has an unpopulated fan cooler aperture moulded into its back panel only lends further credence to this hypothesis imho.
The original motivation for such nonsensical penny pinching may well have been simply that of reducing production costs which, after monitoring this topic thread, would have revealed the warranty voiding efforts of its target demographic soon enough that it seems they'd decided to pretend ignorance of the more egregious defects, electing to apply a cack handed half live mains leakage fix in the 6800 (
and the 6900!) models and leave the remaining defects unaddressed to ensure a minimum of valid warranty returns where they would not only have had to deal with the expense of any repair (in reality more likely just take another unit from their stock of spares set aside for such warranty replacements) but also that of the customer's warranty return shipping costs.
Looking at the way FeelTech have failed to respond to their customers' requests to fix blatant shortcomings, looks very much like a strategy to cut overheads by taking advantage of their customers' propensity to void their warranties (deemed worthless by most anyway) by having a go at fixing the issues for themselves, and thereby reduce the number of warranty returns they would otherwise be obliged to deal with.
However, despite what I think of the situation, I'd still be inclined to replace the 6600 with a 6900 should it ever develop an irreparable fault. After all, for the money, it still represents an excellent bargain in AWG technology for what most of us would consider "chump change".
It's certainly cheap enough to risk improving to a higher standard with an OCXO lockable to an external 10MHz reference and an upgrade of the 85 ohm attenuator to a real 50 ohm 20 dB resistor network plus replacing the earthing wire link to the PE pin of the C14 socket with a 4.7K resistor to eliminate random dc offsets and noise coming in from the mains earth wiring and, of course, fitting a fan into the case for a modicum of active cooling.
Incidentally, the abysmal lack of passive convective cooling airflow proved inspirational in the ventilation arrangements I'd used in my rubidium frequency standard. I needed the cooling fan to be the sole arbiter over the LPRO's base plate temperature so any natural convective flow would have been counterproductive, so it's hats off to FeelTech for a real tour de force lesson on how to achieve virtually zero convective cooling.