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RAF Common 117.9

Old 27th Nov 2018, 12:05
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RAF Common 117.9

I will kick this off for those that recognise the title.

Do you have numbers that are engraved in your memory? How many can remember the Common frequencies let alone remember the numbers?

When did the RAF first create common RAF and Command? It was when crystalised VHF R/T was the main radio system. There were 3 boxes, one was lower VHF and the third higher. The RN had the one in the middle. I can't remember the ranges but the lower frequency was near 112 MHz and the upper near 140 MHz.

The channels I remember were;

RAF Common 117.9
Flying Training Command Common 115.56
Bomber Common Two 135.95

When flying outside controlled airspace, which was pretty much most of the country, we would monitor at least one Common.

Does anyone remember the other Common freqs?
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Old 27th Nov 2018, 13:20
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319.4; wasn't that Waddo approach?
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Old 27th Nov 2018, 14:30
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362.3 is stuck in my memory. After the change to UHF sets, this was the only frequency we had in UBAS Chipmunks, that could be used to talk to other RAF towers during cross-country flights. I remember one air-trafficer, possibly at Syerston, who was surprised and disbelieving that we couldn't switch to Approach.
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Old 27th Nov 2018, 14:36
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Does anyone remember the other Common freqs?
142.29 comes to mind, though I can't recall its function. Yes, the days of crystal tuning, 90kHz channel spacing, and 10-channel VHF sets.

VHF was superseded by UHF in the early 60s; UHF first met by me at Leeming on the JP, 61-62, but back to VHF for the Vampire at Valley 62-63.
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Old 27th Nov 2018, 15:35
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From elsewhere:

At the end of WWII the military air VHF band was 100-156MHz. Transmit frequencies were derived from crystal oscillators working in the range of 5.560MHz to 8.665MHz which were electronically multiplied by 18 to give the transmitter output freq.

The oscillator crystals were manufactured at 5KHz spacing, which when multiplied by 18 gave an output channel spacing of 90KHz. Thus there were some 622 channels available from 100.08MHz to 155.97MHz at the end of WWII.

When civilian aviation started they were allocated 108-128MHz initially (100KHz channel spacing). 108-118MHz was allocated to navaids and 118-128MHz to R/T. The old RAF common freq of 117.9 was so widely used, that it must have been kept clear of navaid use until the RAF finally gave it up. Many civil aircraft also carried 117.9 (it was only a matter of plugging the appropriate crystal in).
As late as 1973, our ULAS Chipmunks still had ancient 10-ch VHF sets, complete with utterly useless obsolete VHF frequencies. No doubt there was some aged Learning Command edict, which no-one had reviewed, stipulating that 'RAF Common' and 'NATO Common' frequencies were to be carried?

When the RAF woke up to extension of the aeronautical VHF band from 136 to 137 MHz, the only way this could be achieved on some of our VC10K V/UHF radios was by sawing off some internal mechanical part, to enable the VCO to go up that high. But this also had the effect of lowering the bottom available frequencies by 1 MHz... , which would have caused interference to some navaids.

The only RAF aircraft I flew which had the full range VHF band (up to 150-ish MHz, I think) was the Hawk T1. Tootling back along a TACAN route from Scotland back to Chivenor once using UHF, I clicked through the VHF radio's channels to see what was there as the coverage included various 2m frequencies used by taxis and other mobile users - as I soon discovered!
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Old 27th Nov 2018, 15:51
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BEagle's mention of 100 MHz reminds me about the RBS frequency used at EAR West Freugh. I think that was the frequency used by the Vulcan's practising pop up attacks..
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Old 27th Nov 2018, 20:12
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From memory - so therefore probably very wrong:
NATO common Approach: 362.3 122.1
NATO common Tower: 257.8 122.1
NATO common Director: 344.0 123.3
NATO common Talkdown: 285.4 123.3
NATO common Fixer: 317.7 ????
I also remember the 142.29 mentioned above on the very old 10 channel VHF ATC standby boxes; the only time I saw it slated for use was in conjunction with some post-apocalyptic Civil Defence/ROC exercise. Needless to say it didn't do what it said on the tin! I think 117.9 may have also been on those antideluvian VHF boxes too, labelled simply 'Common'.

Last edited by Downwind.Maddl-Land; 27th Nov 2018 at 20:21. Reason: Pressed submit before completion
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Old 27th Nov 2018, 21:02
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As late as 1973, our ULAS Chipmunks still had ancient 10-ch VHF sets, complete with utterly useless obsolete VHF frequencies.
That's interesting. Was VHF kept in order to fit in with the WW civil traffic? The UBAS Chipmunks were converted to UHF in the summer of 1968. This was a retrograde step as far as situational awareness went, since over 90% of the other Shawbury traffic was Marshall's fleet of Vampires and Piston Provosts, which of course, were all VHF!
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Old 27th Nov 2018, 21:37
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Does anyone remember the other Common freqs?
As a VHF/DF operator in the 1950's these spring to mind:
  1. R.A.F. Common: 117.9 MHz
  2. Fighter Command Common: 107.28 MHz
  3. Transport Command Common: 135.9 MHz
  4. Bomber Command Common: 103.86 MHz
  5. Fighter Command Metropolitan Sector: 112.86 MHz, 135.18 and 153.9 MHz

Last edited by Warmtoast; 27th Nov 2018 at 22:04.
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Old 28th Nov 2018, 08:46
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Warmtoast, knew someone would know. Almost the complete set there and also the NATO.

If you flew out of area you needed a specially crystallised box for instance to fly from UK to NATO. I remember the AEO swapping boxes inflight as we flew from UK to Malta. Also swapping the crystals whilst airborne.

The Russians only had 4 channels in their fighters so the V-Force comma jamming just aimed to deny them their fighter common. A cunning plan but I think there was a flaw in it
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Old 28th Nov 2018, 08:56
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Warmtoast, those VHF/DF operators were a boon to baby navs. Wending our war up to Wooler on early radio position line exercises the pilot would call up MsG or Acklington for a QTE. After a pause to allow for the reply we might hear ABC12 this is Silloth, your bearing that time was nnn. Two for the price of one.

There was also a deal with the Scily Island Homer. They would bill the RAF for each bearing. Using them meant they got paid; if they got paid they stayed open
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Old 28th Nov 2018, 09:29
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Do y'all know those crystals were valued at 10.00 each?

As a Corporal at Dishforth c1959, at the start of each shift I had to sign for a whole cupboard full of hundreds of the damn things. This was the ARSF 'Crystal Bank!

Each pre-flight, we had a 'Crystal Fit' that was dependent on where the a/c, Hastings & Beverley's, were going to.

A nightmare it was checking all of the crystals in and out and trying to keep a record of which a/c they were all in, and which wireless mech had left one in his pocket.
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Old 28th Nov 2018, 09:50
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I remember Oakington (Varsity) in 1970/71 doing the planning for an ‘airways trainer’, and having to look up the various crystals we would require, and to tell the flight line engineers which ones we wanted for the trip.

We got airborne and joined airways at (I think) BPK and started along the airway to CLN. After a few mins we were told to contact London on a frequency we didn’t have in the box.

There was a waving of instructor hands and an instruction to acknowledge the frequency change and then to keep quiet.

After about a min. the said instructor calls London, on the original frequency, and says that we had no answer on the new one just given.

The reply from London was a request to tell him the frequencies of the crystals we did carry! All a bit embarrassing.
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Old 28th Nov 2018, 13:57
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In the rear crate of our Canberras there were 8x 10 channel VHFs and these quite often needed "fit" changes according to instructions passed down from high.
Quite a job for our w/t engineers, fortunately, being radar, this job didn't apply to me but I can still remember helping by carrying a bag full of Xtals and passing the appropriate one when asked as my mate tuned them. Happy days.
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Old 28th Nov 2018, 14:53
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Down Start Point way I requested a QTE from Culdrose, the pilot refused saying always use Scily Homer support them the R.A.F. have to pay 2/6d for each bearing. Even better was a running fix for 7/6d, the only trouble was it was a manual homer and often class 3!
Somewhere in the depth's of PPRuNe Military there is a thread on "The Dulcet tones of Silloth".
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Old 28th Nov 2018, 14:54
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Yes, I remember 117.9. From an ATC point of view, I certainly remember the comely young ladies who had to monitor all the common frequencies from a compartment behind the approach room. As an 18 yr old newly minted Plt Off at Little Rissington (c 1961) they were a bit intimidating - eyeing you up and assessing you while doing their knitting or reading, earphones on their heads. Quite put me off learning about integrating high & low level QGHs.
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Old 28th Nov 2018, 15:40
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Pom Pax, TY, confirms my memory and agree on running fix. Our trips were assessed on 'activity point's and 'process points'. The more points accrued the less significant mathematical errors.

We soon learnt to 'discard ' one of the 3 bearings and construct a 2 position line MPP thus gaining both activity and extra process points

Might not have been best navigation but certainly best system.
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Old 28th Nov 2018, 21:59
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Warmtoast, those VHF/DF operators were a boon to baby navs. Wending our war up to Wooler on early radio position line exercises the pilot would call up MsG or Acklington for a QTE. After a pause to allow for the reply we might hear ABC12 this is Silloth, your bearing that time was nnn. Two for the price of one.
I did a piece here on PPRuNe about my days as a VHF/DF Operator that includes a full listing of UK "VHF/DF Fixers" in the early 1950's. See here:
RAF Fighter Command VHF/DF Fixer Net Early 1950's
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Old 29th Nov 2018, 18:13
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Ian 16th - Ah yes, the Crystal Bank! At Dishforth and Abingdon we used to collect a 'Route Pack' of Xtals for the VHFs and the STR18s dependent on which route we were on. Over the years I , somehow, 'collected' a personal stock of the most useful which lived in the Nav bag pencil box (still have the box!) When I eventually left Abingdon for Bangkok, I tried to hand in these 'extras'. NO way!! The chap in charge didn't want to know - the addition of some dozen or so xtals to his aready audited stock would create HUGE problems!!
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Old 30th Nov 2018, 17:59
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Also swapping the crystals whilst airborne.
Yes, well, easy enough in a biggish aircraft, I imagine. Not so easy in a Prentice on route to Sharjah from UK decades ago, with a box of 80 crystals bought for the route. The prehistoric VHF, mounted right behind the pilot seat with a controller on the panel, had 4 channels (A, B, C, D), rarely enough for a complete flight. So "Contact TWR on...." often meant acknowledging, switch radio off, find crystal for TWR frequency, reach behind seat, feel for the crystal in the channel to be changed, pull it out, push in replacement, unplug aerial feeder from set, also by feel, plug in bit of wire with bulb on the end, switch on, use left hand to transmit, right hand to twiddle the aerial tuner for max light, pull out wire with bulb on it, replace aerial feeder, call TWR. By definition, this often took place while on final approach, enough time in a Prentice at approach speed if started 1-2 miles out or before, but the aircraft still had to be flown while all this was going on. ATCOs were sometimes insensitive enough to comment adversely, even rudely about the delay, and occasionally seemed unable to understand and accept the explanation that changing crystals takes time and patience.

I've always thought that simply pushing buttons to select a new frequency is for sissies.
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