Absolutely right!
Well, the deviation with a 3.5kHz modulation will be 3.5kHz either side. The 300Hz lower limit is irrelevant.
Ok, I was not aware of the difference on transmit/receive bandwith. Now i understand the transmit is always narrow, thanks. Not changing the practical side but good to understand it anyway.
Archer-181 wrote:
So if one has a .005Mhz frequency or a .000 MHz frequency
Please don’t use the term “frequency” with 8.33 radios. It only serves to confuse matters (which some recent postings in this thread has shown). The proper term is channel. The .005 and .000 channels both use the .000 frequency.
you can use either your new or old radio (with no risk of TX interference).
I theory you can’t because the transmission frequency of a 25 kHz radio may be off sufficiently to cause difficulty for the other party to hear your transmission if you use it on a 8.33 channel — or even cause interference with a neighbouring channel. In practise any modern 25 kHz radio with digital tuning is likely to have sufficiently good frequency stability anyway.
The point cannot possibly be lost on the European CAAs that the 8.33 move will “conveniently” force the discarding of stuff like this
which often only just barely works. Go for a flight on any weekend and you hear plenty of crap radios… I know of a little radio repair shop which is continually repairing this exact type so it looks like the owners want to keep them going for as long as they can. And I can understand it… installing a new 8.33 radio is a good 4 figures, plus most avionics shops are incredibly busy right now.
In practise any modern 25 kHz radio with digital tuning is likely to have sufficiently good frequency stability anyway.
I think anything made since about 1990 will be plenty accurate enough. A search here on “TXCO” digs some old posts. It is the 1970s stuff which is likely to be a problem.
Peter wrote:
… repairing this exact type so it looks like the owners want to keep them going for as long as they can. And I can understand it… installing a new 8.33 radio is a good 4 figures, …
As much as I am in favor of preserving old stuff (and collecting some of it), financially it doesn’t make much sense. If the repairman charges an hourly rate off which he can pay his rent and feed his children, this kind of antique will cost the equivalent in maintenance every two or three years as the installation of a modern unit straight away. And this is not even accounting for ground time/lost flying time and the cost involved of getting stranded somewhere with a defective aircraft.
For that same reason the owner of “my” FTO, who really hates to throw money at his aeroplanes just like any other flying school owner, has had the old panels of all his IFR trainers replaced with Garmin 500 glass panels and Garmin avionics stacks. A big investment as it seems, but zero maintenance for at least one decade to come and no avionics related ground time any more. The financial break even should come after five years or so.
Well, yes, I tend to agree, except that radio repairs here in Europe are a tricky subject because officially you are supposed to get an EASA-1 form for the repair, and nowadays very few shops can do that, especially on something that has not been officially repairable (manufacturer supported with a parts supply) for decades. It’s a bit like this – see especially post #14.
So most of this type of work is done off the books, and consequently is quite cheap 
I’ve always thought the kx175 was a good unit. No how to use manual required.
I certainly know of people who are keeping them. Largely because they are already fitted and it allows them to keep Nav aspect of the unit.
I don’t disagree with what you say what next but some people and schools for that matter simply don’t have the cash to install 8.33
Denmark has just issued AIC A 06/17 clarifying 8.33 status within the FIR. The main exemptions from 8.33 requirement is VFR flight outside Copenhagen TMA below FL195. However, there is a list of ground stations exempted; these seem to include all stations except ACC ! i.e. FIS, A/G, TWR, APP and most OPC frequencies.
It is easy to check whether there is a “Y” in the equipment field in the ATS flight plan – but I am not sure if or how anyone could detect if an aircraft does not actually have the 8.33 capability. Unless you are requested to use the one OPC frequency in use that is 8.33, at EKBI.
The exemption is valid until 1/1/2021, or possibly 1/1/2023 “pending a network impact assessment”.
This is a short video showing the offset carrier (called “climax” in the UK) system, used for area FIS frequencies; these cannot go to 8.33
