[ARC5] OT: X-15 Radios
Brian Clarke
brianclarke01 at optusnet.com.au
Sat Dec 1 20:10:17 EST 2018
Is that really the best? For such an expensive system?
When you get equal signals from two antennas, they can be pointing many degrees off alignment because of the insensitivity – the shape of the response curve. You’re effectively looking at the top of a sine curve.
If, on the other hand, you go for the Adcock design where you seek a null, again because of the shape of the response curve, ie, where the sine wave crosses the zero line, you can easily point within less than one degree.
Yes, I know response curves of antennas don’t correspond to sine curves; they’re closer to sine squared. Nonetheless, the resolution principle is the same.
When searching for pirate radio operators, we have found that two sightings, ie, from two different azimuth points, with an Adcock antenna, gets the culprit very quickly. With the other system, even with three sightings, the resolution is never to one point – you get a triangle. This kind of difference is a good learning tool for new ‘fox hunters’.
73 de Brian, VK2GCE
From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On Behalf Of bob at vanirmail.com
Sent: Sunday, 2 December 2018 8:21 AM
To: Michael Bittner; David Stinson; ARC-5
Subject: Re: [ARC5] OT: X-15 Radios
Hi Mike.
If I were designing this DF system for the X-15 I would install small titanium stub antennas on each wing with the fuselage shielding one antenna from the other. No need for the turntable mechanism since you will always want the homing signal to be located at your destination runway. When the signal is equal at both antennas you are pointed toward home. (Or pointing 180 degrees away!)
Bob K7IRK
-------- Original Message --------
Subject: Re: [ARC5] OT: X-15 Radios
From: "Michael Bittner" <mmab at cox.net>
Date: Sat, December 01, 2018 12:24 pm
To: <bob at vanirmail.com>, "David Stinson" <arc5 at ix.netcom.com>, "ARC-5"
<arc5 at mailman.qth.net>
I'm wondering where is an RF transparent place to put this in a titanium X-15. Also, how long would it be needed to glide back to Edwards AFB from the US/Mexico border after the rocket runs out?
Mike, W6MAB
----- Original Message -----
From: bob at vanirmail.com
To: David Stinson <mailto:arc5 at ix.netcom.com> ; ARC-5 <mailto:arc5 at mailman.qth.net>
Sent: Saturday, December 01, 2018 11:43
Subject: Re: [ARC5] OT: X-15 Radios
Here's a pictorial of the system minus a couple of parts.
<http://jproc.ca/rrp/rrp3/argus_ara25.html> http://jproc.ca/rrp/rrp3/argus_ara25.html
Bob K7IRK
-------- Original Message --------
Subject: Re: [ARC5] OT: X-15 Radios
From: <bob at vanirmail.com>
Date: Sat, December 01, 2018 11:04 am
To: "David Stinson" <arc5 at ix.netcom.com>, "ARC-5" <arc5 at mailman.qth.net>
Since it came up:
Back when the crust was still forming, and the political uproar was "Global Cooling", we used a modified version of this UHF ADF antenna on twin-engine Cessnas for tracking high altitude research balloon payloads. The antenna consisted of a turntable about 78 RPM record size with two vertical stub antennas separated by a silver-plated fence so that one antenna couldn't see the other. The magic was done in an ARA-25 box which generated a 100 cycle square wave used to gate ON one antenna, then turn it off and gate ON the other. Servos drove the turntable until the signal level from one antenna matched that from the other. An ID-251 (?) panel meter pointed to the signal source. Simple, effective, and fiendishly sensitive.
How sensitive? We left Denver one morning and a few minutes later were able to track a 2 watt balloon telemetry signal out in West Texas over 400 nautical miles away!
In a prior life, Pete, WA5JCI used this system and helped maintain it. Are you here Pete? Do you remember if the pilot's display meter was an ID-251? Both ADFs went to one meter with two needles.
A truly wonderful system that worked down into the noise.
Bob K7IRK
Tillamook, Oregon
-------- Original Message --------
Subject: [ARC5] OT: X-15 Radios
From: "David Stinson" arc5 at ix.netcom.com
Date: Sat, December 01, 2018 7:51 am
To: "ARC-5" <arc5 at mailman.qth.net>
Since it came up:
According to the North American Aviation
X-15 Flight manual, Section 4-7:
COMMUNICATION AND ASSOCIATED ELECTRONIC
EQUIPMENT.
UHF COMMUNICATION AND ADF SYSTEM.
The UHF communication and ADF system enables the
pilot to transmit and receive voice transmissions
and to obtain visual course reference on the
course indicator.
The system has two modes of operation, normal and
alternate. During normal operation, the
UHFtransmitter and main receiver ("MAIN")are used
with a UHF antenna for communication, and the
auxiliary receiver
("AUX") is used with the ADF antenna for automatic
direction finding to operate the course indicator.
The alternate mode is used in case one of the
receivers fails and it is desired to regain the
function of the inoperative receiver. During this
mode of operation, the UHF transmitter is
connected to the UHF antenna through an automatic
lockout feature. The main receiver is connected to
the ADF antenna for ADF operation.
The auxiliary receiver is connected to the UHF
antenna for communication reception. The
transmitter and main receiver cover the frequency
range of 255.0 to 399.9 megacycles for 1750
channels, spaced at 1OO-kilocycle increments.
NOTE
Frequencies below 265 megacycles should not be
used, because they are reserved for telemetering
channels and the system will not accommodate this
frequency range.
The guard receiver, an integral part of the
system, operates off the UHF antenna and guards
the preset frequency of 279.9 megacycles. The
guard receiver has two functions: it operates the
automatic antenna selector, and it also provides
for reception of voice transmission of the guard
frequency (normal guard operation). The auxiliary
receiver has 20 channels in the frequency range of
265.0 to 284.9 megacycles, with one channel per
megacycle increments. The system has a dual power
supply, which gives the equipment continuous
operation if one of the power sources fails. The
main power source for the system is the
three-phase ac and the 28-volt dc systems, and
protection is afforded by circuit breakers.
Controls for operation of the UHF communication
and ADF system are on the radio control panel
(figure 4-2), on the left console.
UHF Communication and ADF Controls.
F\mction Selector Switch. A rotary-knob type
selector switch, on the radio control panel,
controls the mode of operation, either normal or
alternate, and also selects the antenna of best
reception. The switch is marked "MAIN REC" and
"AUX REC" and has a two-headed arrow across the
full diameter of the rotary knob. On the outer
perimeter of the knob is the position marking
denoting the function of the system. OFF, T/R, and
ADFare the positions for the main receiver; REC,
ADF, and OFF are the positions for the auxiliary
receiver.
The switch is designed so that when the arrow
indicates OFF on the main system, the opposite
arrow is indicating OFF on the auxiliary system.
With the switch in the T/R position on the UHF
receiver-transmitter, the auxiliary receiver is at
the ADF position. This is the normal mode of
operation, and the main receiver is connected to
the UHF antenna for communication. At the same
time, the auxiliary receiver is connected to the
ADFantenna for automatic direction finding. When
the main receiver is at ADF position, the
auxiliary receiver is at REC. In this alternate
mode of operation, the main receiver is connected
to the ADF antenna for automatic direction
finding, and the auxiliary receiver
operates from the UHF antenna for reception of UHF
voice transmission. The functions of the main and
auxiliary receivers are then reversed, provided
the main and auxiliary channel selector knobs are
reset to the channel that corresponds to the
frequency of the desired ADF and UHF signals. In
other words, when the function of the two
receivers is changed, the channel selectors must
be changed to provide the correct operating
frequency for the individual receivers.
NOTE
The main channel selector control sets up the
frequency for the transmitter as well as the
receiver. When the main receiver is used for
automatic direction finding, the transmitter, if
operated, transmits on the ADF frequency, which is
not recommended procedure. For proper
transmission, the main channel must be set to the
proper communication channel before transmitting
and then back to the ADF channel for reception of
ADF signals. Using the main receiver for automatic
direction finding is an emergency procedure only.
Volume Controls. There are two volume controls on
the radio control panel, marked "MAIN" and "AUX."
When either of these rotary volume controls is
rotated in the direction indicated by the arrow
(clockwise), the volume of the respective
equipment to the pilot's headset is increased.
Counterclockwise turning of either volume will
diminish the volume of the equipment being
adjusted.
Channel Selector Knobs. There are two rotary
selector knobs on the radio control panel used in
selecting the desired channel frequency of the
equipment in use. The UHF transmitter and main
receiver channel selector control provides
selection of 20 preset channels within the
frequency range of the UHF receiver-transmitter.
A similar channel control selector enables the
pilot to select one of 20 channels on the
auxiliary receiver.
Channel Indicators. There is a channel indicator
window to the right of each channel selector knob.
The upper window, marked "MAIN," shows the channel
number that has been selected for the UHF
transmitter and main receiver. A similar window,
marked "AUX, " to the right of the auxiliary
receiver channel selector knob, displays the
channel selected for the auxiliary receiver.
Antenna Selector Switch. A two-position switch
(13, figure 1-3), on the left console in the
cockpit, affords the pilot manual selection of
either the upper or the lower antenna for both the
UHF and the radar beacon system. The switch is
marked "AUTO" and "LOWER."
With the switch at AUTO, the antenna operating
with the greatest signal strength will be in use.
When the pilot selects the LOWERposition, the
lower antenna will be in operation. The switch is
powered by the primary dc bus.
Azimuth Indicator. The azimuth indicator (7,
figure 1-2), on the instrument panel, consists of
a movable compass card, an index marker, a
pointer, and an adjustment knob that is used to
rotate the compass card to the desired heading.
The needle provides visual indication of the ADF
station direction from the airplane D T. O.
1X-15-1 Section IV heading, for homingoperation.
The indicator also has a synchronizer knob and an
annunciator used with the inertial flight
reference system. [Refer to "Inertial All-attitude
Flight Data System (Gyro-stabilized Platform)"
in Section I.]
Operation of UHF Communication and ADF System.
Normal Operation. The normal operating procedure
is as follows:
1. Function selector switch - TIR (main system).
2. Main channel selector knob - Select desired
channel.
3. Auxiliary channel selector knob - Select
desired channel.
4. UHF antenna selector switch -AUTO or LOWER as
desired.
5. "MAIN' and "AUX" colume controls - As desired.
Alternate Operation. If the main receiver fails,
the auxiliary receiver is used. To use the
auxiliary receiver, proceed as follows:
1. Function selector switch - ADF (main receiver).
The auxiliary receiver selection will be at REC.
2. Main channel selector knob - Select desired
channel.
3. Auxiliary channel selector knob - Select
desired channel.
4. "MAIN"and "AUX" volume controls -As desired.
NOTE
If the UHF transmitter is operated while the main
receiver is using the ADF antenna, a temporary
lockout feature transfers the UHF transmitter to
the UHF antenna.
GL OM ES 73 DE Dave AB5S
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