Old ADF
 

Wondering if I can get some help here!
A Cessna aircraft I'm now flying has a very old ADF (1969) - it's one with a big dial in the middle. I've seen one in a PA-28 too.

Being used to a "normal" ADF with a digital output I'm a little perplexed by this device and wondering if anyone knows how to translate frequencies in the chart onto the ADF? It seems to have various subscales and a selector for decimal point position.

Twiddle them till you figure it out?

A picture might help, but generally speaking - the old ones I have flown have a single knob per digit (hence 3 knobs below each digit). When you turn them you should see one of the 3 digits change, and hence get your frequency dialled in.

Sorry if this is a little vague!

These old ADFs are very easy to use.

1. Cover it up with a suitable sized piece of card saying "INOP" in large friendly letters.
2. Use something invented since WW2 for navigation - an iPad works very well.

hahaha best thing I've read in a while!!!

Not sure about what you described. Is it an analog tuner? If so, from memory:

Controls/switches:

* Just like a digitally tuned ADF, it will have a selector, or a couple of selectors, for OFF, ANT, ADF, and BFO.
* It will also have a band/frequency range selector. Use it to tune what frequency range on the analogue scale you wish to tune.
* Frequency scale
* A signal strength meter.
* A tuning knob

To tune a station:

1. Determine the frequency you wish to receive
2. Select the frequency range selector to cover the particular frequency you wish to receive
3. Switch to ANT
4. Select ADF audio 'on' on the aircraft's audio panel
5. Rotate the tuning knob until the needle on the frequency scale is close to the frequency you want.
6. Slowly turn the tuning knob so that the needle continues to move towards the desired frequency.
7. Watch the signal strength meter until it peaks. You may have to slowly rotate the tuning knob back & forth to be satisfied you have the best signal.
8. Listen to the morse ident to confirm the correct station. If it's not correct then you've tuned the wrong station. Check each of the steps above. If you can't hear anything, and are tuning a French NDB, select BFO to add sound to the signal.
9. Select 'ADF' to activate the DF function.

OK Tinny, now see if anyone knows what the BFO function means and/or does.

CC

I miss the one I used to use. It came with a massive aerial running from the tip of the fin to above the cockpit, and made me feel like I was in a DC3. Plus it had excellent gain - it dated from when ADFs were new and exciting.

The digital one may be half the size and a tenth of the weight but somehow it's a bit anodyne.

PS if in doubt, post a photo and we can probably help!

Is it an old Bendix T12?

http://www.hasselbusch-esbeck.de/df2...e/bendix_a.jpg

They are very easy to use.

I used to use one of those in an old Piper twin on the night mail run - it was absolutely fantastic!


For listening to Atlantic 252 :ok:

They don't make em like this anymore.

1. Select the frequency band you need on the right
2. turn the middle knob until you have the approximate frequency shown on the dial
3. fine tune for maximum strength on the left hand meter
4. listen and identify the morsecode.

BFO- Beat frequency oscillator. Not required in the UK but I am told it was required to ident NDB's in France.

Am I correct?

Correct..............

CC

The big plus with these tuneable receivers is that if you're getting interference, you can very slightly de-tune to improve reception - the signal strength meter might be picking up interference. Harks back to the days of trying to tune in Radio Luxemburg - '208, your station of the stars!' Maybe you'll be able to get the Light Programme, or if you're a serious wireless listener, the Home Service. We still get that, locally, on 756 kHz, very handy for practice holds.
If you have such an ADF and it still works, then I'd hang on to it, for as long as there are NDBs about, of course, which might be quite some time.

TOO

BFO is required to hear any A1 signal as it has no modulation and therefore no tone, unless it has something to beat against.
There is no ADF in the World with a digital output! It may have a numeric display, but so does the tuneable one where 300 = 300 and 11 = 1100. Don't people learn to use rulers any more?

Jay Sata - Yes it is!!

Tinny - thanks for the guide. I'm trying to understand how the three scales shown on the dial actually relate to the frequencies displayed on a map - would you have any idea?

That's as maybe but some of use grew up after slide rules and analogue radios and consequently have no idea how on earth these old bits of kit work!

Next to the red 'test' button, is that the volume control knob?

And where is the BFO selector? Is it the CW position?

I have used one of these, I think it was in an Aztec in about 1978.

The one in Jay's picture is tuned to 258kHz. The selector switch on the right selects which range of frequencies is tuned and you rotate the dial referring to the appropriate scale to a position that equates to the frequency you want. All NDBs are low frequency around the bottom of the medium wave broadcast band so their frequencies are in a few hundreds of kHz.
Just to make it a bit more fun, the scale might be inaccurate by a few kHz, which is why you need the Morse identifier to confirm you are tuned to the right beacon.

Most NDBs are amplitude modulated with a tone so you don't need a bfo. Bfo would be needed to hear the tone (so you can read the Morse) if it is carrier wave only (A1 modulation: that means the Morse is sent by turning the signal itself, or 'carrier wave' on and off.

1940's technology but good stuff nonetheless.

I agree with you Heston. I was based near the Bristol Channel decades ago and could navigate direct back from France using the 75 killowatt BBC Wales transmitter at Washford. I could pick it up on the ground at Schipol.

They were wonderfull bits of kit in Australia where a MW radio station could be used as a homing beacon and provide in cockpit entertainment.

n5296s
 

Spoken like a true child of the magenta line.........

Shall I get my Astro compass ?

:-) I'm amazed how long it took someone to say this.

I love vintage things as much as anyone. I have a fantastic example of a 1950s electromechanical calculator sitting on my desk, but I don't use it to do my taxes. I use 1950s era valve amplifiers to listen to music, but my avionics are all firmly solid state. I'm a huge fan of the vintage computer work going on at the National Computer Museum, but I use a Macbook to do actual computing.

I can and have navigated with everything available, yes even including ADF/NDB - even flew an NDB approach to perfection on my IR checkride. But that doesn't mean it's a good idea.

The ONLY role of ADF/NDB in the 2010s is to get through checkrides etc that demand it. It has no more role in practical (and safe) navigation than the four-way range or the large arrows formed on the ground across the western USA. The FAA has (finally) dropped them from its written tests (so I'm told - they were still there for mine). Just as well, because there are very few NDBs left here.

The CAA seems to operate on the basis that it is still 1949. That's just something you have to live with if you want to fly in the UK, but it doesn't make it a good recipe for practical flying skills.

Agreed.

Morse and signal squares are relics of a bygone era.

Airfield NDB's with morse idents were just an additional pilot workload.

The USA used weather and airfield info on the NDB instead of morse code.

The old ADF system was useful in its time.
https://en.wikipedia.org/wiki/Non-directional_beacon

Sure, I totally agree. But how do I fly an ILS approach at say Cambridge, where I need an NDB...if I don't have one? Do I use SkyDemon (which in all truth is probably more accurate, but would technically be illegal)?

Have a play with it...you'll have fun.

You have an ADF installed in the plane, just in case you get ramp-checked. Then what you actually fly is using your installed, approved GPS. I'm sure you're not seriously suggesting that someone would be flying for-real IFR in 2017 without a GPS in the aircraft.

For a start it isn't my plane, unfortunately.

I am. It's not a legal requirement and, as much as I agree with you it is necessary I don't think it will happen. I will campaign with the owner but I doubt he has £10k to spend...

Fair enough. In that case you buy an iPad and run some appropriate nav software on it (Foreflight in the US but not sure that exists in the UK), and a nice yoke mount. It's not approved but it has a much smaller chance of flying you into the nearest thunderstorm.

If you're a student then my comment about for-real IFR doesn't really apply. You probably should figure out how to tune the thing, even though it belongs to the era of Buddy Holly and cars with tailfins. Make sure you have a supply of replacement valves for it too. Those ECC88s hate being shaken about.

Yeah, that's what I was thinking but I don't think we have a Foreflight equivalent over here - the closet would be SkyDemon but that is VFR only.

I'm not but I was taught on steam gauges, however this rotating dial thing is a little too old even for me!

I agree, as long as you don't confuse it with something you'd use for navigation. I was quite sorry when mine died and I had it removed. It was great for keeping track of how many times you'd been round the pattern. You could listen to AM radio (not that I ever did). And since there's a 100MW or so* AM station very close to my home field, I could see the direction to home from cruise altitude anywhere in California. Reassuring though not enormously useful.

*<pedant_alert>Really 50KW</pedant_alert>

Even if it's VFR only, if it will give you a magenta line to the navaid in question it will do the job. IT doesn't know you're on an IFR flight plan.

Yeah, I think I'm rather resigned to using SkyDemon given my options. It does have a rather good airways mode to be honest...!

Plenty of them still around.

I've been around long enough that I immediately figured out the controls in Jay's picture, except for the unmarked knob next to the test button. Is that for fine-tuning?

MW AM radio - that takes me back. Who says nostalgia ain't what it used to be!

Radio Luxemburg 208
Radio Caroline 199
Radio London 266

I remembered the first two but had to look up Radio London's wavelength.

When I started flying it was this sort of ADF along with a ribbon DI
http://thumbs.ebaystatic.com/images/...roP/s-l225.jpg

Nowadays you can visualise where the needle should be on the DI, with the ribbon DI you really had to work it out in your head.
Even worse was doing the RN Observers course in the Sea Prince, in that you were often working off marine beacons - these only transmitted for a set period, IIRC something like 2 minutes every 10 minutes, it was a "coffee grinder" ADF setup operated by the pilot where you set the frequency, idented the beacon then actually rotated the aerial to get the bearing! This was then called down to the nav students in the back of the aircraft!

The red test button confirmed if the ADF needle was live, i.e. not stuck.. The black knob to the right was for volume (audio output).

One would have to consult the Bendix Operator's Manual, but CW could also mean Continuous Wave: i.e. Morse Code transmission.

A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency; a sine wave. In mathematical analysis, it is considered to be of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a sinusoidal carrier wave is switched on and off. Information is carried in the varying duration of the on and off periods of the signal, for example by Morse code in early radio. In early wireless telegraphy radio transmission, CW waves were also known as "undamped waves", to distinguish this method from damped wave transmission as effected by early spark gap style transmitters.

I am boggled by the inability of anyone flying without an Ipad.

What is wrong with a map, a line and a bit of basic nav?

Doesn't work very well in IMC when you're trying to line up with a runway.

Well, me (waving hand). Though it was 2015. But there I was, having to fly what amounted to a for real IFR approach, in what was generously agree were special VFR conditions. The 182 I was flying is equipped with a KX165 (ILS & Glideslope) and a KR87 ADF. It also is equipped with a Garmin GTN750 GPS Comm, Garmin G500 glass cockpit, and a full set of "steam gauge" instruments. And, a complete set of approach plates for the airport.

I'm confident that the GTN750 coupled to the G500 is ultimately capable of presenting everything a pilot could want to fly an awesome GPS approach. But, the KX165 and KR87 provided what I needed. I flew the approach as best I could relative to the approach plate, with the tower's concurrence, and did just fine. I ignored the GPS so as to prevent task saturation, and everything worked out just fine - just as it always did when I would fly several actual ILS approaches in the Aztec each week in the early '80's - before GPS was known.

I do accept that ADF and ILS will be decommissioned, and some of us dinosaur pilots will have to learn new techniques. But, in the mean time, the equipment is there, it is reliable, and happily easy to understand.

I have flown long night winter legs over unpopulated areas with an ADF being the only means of navigation, and it worked just fine. My friend and I flew the length of Africa in a Twin Otter, in which though there was a VOR/ILS, the two ADF's turned out to be the better means of long range navigation at Twin Otter altitudes. Again, before GPS (though my friend had some kind of pre GPS sat nav unit (about the size of a typewriter), which consumed a lot of his interest, with him merely popping up from time to time to tell me I was on course.

To my amusement, and his frustration, I found a trick. This aircraft had dual RMI's, with no directional gyro (so the compass cards behine the ADF pointers would show the magnetic heading based on a remote wing mounted compass head). The RMI's would fail from time to time while we flew. They would drop a flag, and the card would no longer turn. No longer useful as a heading indicator - or were they?

He confirmed with his sat nav, over disappointingly long intervals that I was keeping my heading really well, considering that the most I had to use was the wet compass. How was I doing it? I would not tell. At the end of the trip, I had to answer up, so he did not explode with curiosity. I noticed that if the RMI card failed and stuck on the desired heading, I could use the RMI slaving meter as a quasi VOR indicator. If I turned even a degree off course, the slaving meter would try to slave the RMI face back, but could not, so it would show "unslaved". I could reslave by returning the aircraft to the required heading by reference to the slaving meter indication. It worked a treat, and very precise. But the downside was that it required an RMI to fail on the desired heading.

The very long distance [away] NDB's supplemented this crude navigation means, because the ADF could receive those signals. .

Works well until the ADF decides that a Cb is more attractive than the NDB you are trying to use!

Did it yesterday and will probably do it again next week - not a problem.