Ontario Surplus, Inc.



AB-577/GRC Mast


The AB-577 mast is an all-aluminum tower designed to be field deployed by one or more people. It does not require a prepared surface or foundation of any kind. The kit consists of a launcher, eight tube sections, guy wires and all hardware and tools to assemble a 50 foot mast (see complete parts list below). A total height of 75 feet is possible with the addition of the MK-806 extension kit. Useful for any application requiring a temporary or permanent tower such as lighting, surveillance, emergency communications or RF survey work. The quick erection time also makes the mast very useful for antenna experimentation and use in neighborhoods where a permanently installed tower is not allowed.


Tower and guy locations are laid out using the supplied radius rope. The tube carrier is removed from the launcher and the locking pins for the brake, the elevator and the winch reel are removed. The top adapter is attached to a mast section and the mast section is installed and locked with the brake in the top of the launcher. The top guy ring is installed over the top adapter section and the longest guy wires are connected to the guy ring. The antenna may be attached to the top adapter at this time or after the launcher has been guyed. Anchors are installed and the base of the launcher is pinned to the ground. The first set of guy wires is connected to the top of the launcher and adjusted using the built in level to hold the launcher in a vertical position. The elevator mechanism is lowered to the bottom of its travel. A tube is inserted and clamped to the already installed top section. The brake is released and the winch is used to raise the elevator platform and tube to its uppermost position. The mast is locked in place and the elevator is lowered back to the bottom. Another tube is installed and the process is repeated. During the installation of the fifth tube the middle guy ring and associated guy wires are attached to the mast. When all mast sections have been installed, the guy wires are secured to the anchors and tensioned. Under windy conditions or when erecting to 75 feet, the guy wires should be tended by additional people to maintain the tower in a perfectly vertical position. The entire mast sits on a bearing assembly and may be rotated from the base using the supplied wrench. This allows for antenna positioning from the ground without the use of a rotor. For additional information we recommend purchasing a copy of the technical manual (see below).

Click here for detailed guying diagrams

Parts List for AB-577/GRC

Description Qty
Mast base (launcher) 1
Carrier assembly (for mast sections) 1
Mast section (5 inch diameter) 8
Bag, roll type (for anchor components and tools) 1
Anchor, guy (36" screw type) 3
Stake, guy GP-112 (rock and ice stake) 3
Stake, GP-2 4
Bag, BG-102 (for guys and accessories) 1
Guy assembly, blue (36 or 39 feet) 3
Guy assembly, white (44 or 47 feet) 3
Guy assembly, red (62 or 65 feet) 3
Guy attaching ring, top 1
Guy attaching ring, middle 1
Adapter, antenna (top section 2.35" dia. x 7" H) 1
Clamp, rim clenching (joins sections) 8
Halyard (radius rope) 1
Winch assembly (gearbox and handle) 1
Wrench, spanner (for rotating mast from base) 1
Technical manual 1
Hammer, 6 or 8 lb 1
Digging bar 1

Parts List for MK-806/GRC

Description Qty
Case, mast extension 1
Mast section (5 inch diameter) 5
Anchor, guy (36" screw type) 3
Stake, guy GP-112 (rock and ice stake) 3
Bag, BG-102A (for guys and accessories) 1
Guy assembly, green (78 feet) 3
Guy assembly, orange (98 feet) 3
Guy attaching ring, middle 1
Clamp, rim clenching (joins sections) 5

Shipping Information

The AB-577 mast ships in three pieces with a total weight of approximately 310 lbs plus packaging materials. The launcher assembly is the largest piece (96 x 13.5 x 23 inches) and weighs 190 lbs. Due to the size and weight, the kit must ship by truck. See the FAQ page for more information on shipping by truck.


We now have complete masts in stock for around $1500.   Also, if you have one or more to sell, we are always buying.  Spare parts are also available as shown below. 

To keep costs to a minimum, optional items are broken out as much as possible.  A basic 50' AB-577/GRC mast kit consists of the following:

The basic kit includes everything special needed to put up a 50' mast.  Also required will be a hammer to pound in the stakes.

Not included but may be available:

Spare Parts List for AB-577/GRC

Description Unused Used Notes
Mast sections NA NA  
Mast clamps $10 $7 set of 8 for $65 or $50
Adapter, antenna $90 $60  
Guy ring, top $90 $60 set of top adapter and guy ring $150/$100
Guy ring, middle $90 $60  
Guy cable, blue 36' NA NA substitute 44' guy
Guy adjuster with cable, white 44' $35 NA bare stainless
Guy cable. red 62' NA NA bare stainless
Guy cable, red 62', coated $40 NA black jacket
Winch assembly $130 $90 gearbox and handle
Spanner wrench $35 $20  
Technical manual $12 NA includes postage
Winch cable for launcher $50 NA  
GP-2 Stakes $12 $8  

Call or email for other repair part needs, we have almost everything to repair the AB-577 mast.