Back to Home   Technical Information, Construction Information and Modifications for Bird Electronic Test Equipment
Compiled by Mike Morris WA6ILQ
Maintained by Robert Meister WA1MIK

Click here to go to the Bird Electronic Corporation web site. There is also a "Bird Component Products, Inc." and a "Bird Technologies Group."

If anyone has photos of Bird coaxial resistors, coaxial attenuators, or other non 43-series equipment we'd appreciate it, and we'd be happy to give photo credit.

A brief rundown of Bird model numbers that I've run across (note this is not intended to be a comprehensive product list, just a list of what I've used and seen):

43   General Purpose wattmeter
81B   80 watt dummy load, female N connector, no metering.
694   1Kw 2-30 MHz oil-filled continuous duty Termaline - uses standard QC connectors - with a flip-up steel protective cover over a meter calibrated to 1000 Watts.
4041   Relative Field Strength Meter.
4275-020   adjustable (-60 dB) signal sampler for 20 MHz to 1 GHz, 1kw, BNC output. Uses standard QC Connectors for the main RF line.
4304A   Fixed 25-1000 MHz, 5-500W, Portable, see note below.
4305A   Portable, High-Power.
4308   Cellular Specialist, Portable.
4300-400   Conversion Kit for Model 43 Wattmeter to accurately read peak power in AM and SSB.
4314B   PEP, Single element, Portable.
4360 / 4362 "Ham-mate" thruline for HF (1.8-30 MHz, model 4360) and VHF (140-180 MHz, model 4362).
4410A   Multiple ranges with the same (special) slug, 5% Reading Accuracy, Portable.
4431   A variation on the 43 that adds a variable RF Tap, see the note below.
4520   The 45 Series are rack panel mounted wattmeters.
6734-030   2-35 MHz oil-filled 500 watt continuous duty Termaline with a removable meter calibrated in 3 ranges (25 Watt, 100 Watt, 500 Watt) plus "Off".
8135   A later version of the 81B, 150w, uses the quick-change connectors, DC to 1 GHz at 1.1 max SWR, 1 to 2.5 GHz at 1.2 max, 2.5 to 4 GHz at 1.3 max.

The most popular Bird product is the model 43 "Thruline", which has a list price in the US$700 range. The name comes because it is designed such that the RF power has to go through the meter. It was originally designed for the military, and gained wide acceptance in the LMR industry. It uses a plug in element to adjust the frequency and power level. Some folks call the plug-in element the "coupler", or "plug", but the word "slug" is the term I've heard used the most. The frequency range is 450 kHz-2700 MHz depending on the slug used. The power handling range is 100 mW-10 KW, again depending on the slug.

The "Termaline" models are dummy loads with a wattmeter built into the housing.

The 4304 series has a front panel five position selector switch (5 Watts, 15 Watts, 50 Watts, 150 Watts and 500 Watts) and uses an element unique to this model series. It also uses a 20uA meter, not 30uA like in the 43 and 45 series meters.

The 4360 and 4362 were designed specifically for the amateur radio market and use internal fixed couplers. The 4360 covers the HF region from 1.8-30 MHz in two ranges of 200 and 2000 watts. The 4362 is designed for the VHF region from 140-180 MHz with two ranges of 25 and 250 watts. It will work at 220 MHz and UHF but the higher frequency results in overcoupling and the meter will read high (the spec calls for under 5% in the specified frequency range).

The 4410 series has a front panel seven position selector switch with the following markings (multipliers): Off, 0.1, 0.3, 1, 3, 10, 30, 100, BAT (to read battery voltage). It also has an internal 9v battery. The meter itself is unique to this series of meter.

The 4412 series is a 4410 with an internal power supply. The AC cord uses a standard IEC connector (like on the back of your computer) plus there is a 120/240 volt switch. Obviously it is designed to be used as a bench instrument, not a portable meter.

The 4314 has an internal peak-reading option. It is made up of a small circuit board that mounts on the back of the microammeter itself, an on-off switch, two 9v batteries (in series for 18vDC) and a switch that is labeled "CW" or "Peak". There is an external power jack on the left side (18vDC). If you want to modify your own meter you can buy an add-on kit from NM3E.

The Bird 45 series are basically a rack-mount version of the model 43. The 4521 has a single line section (i.e. use a single slug), the 4522 can measure both forward and reverse power with two line sections (using two slugs). It has a single meter and a toggle switch to select between the two slugs. The 4527 has dual line sections, dual meters and a sampler output.

The Bird 4430 and 4431 series are 43 variants that adds a built-in variable signal sampler unit connected to a BNC connector (on the right side of the meter) for monitoring the transmitter output on a spectrum analyzer, frequency counter, oscilloscope, etc. It uses standard Bird 43 family elements. The coupling of the sampler port can be varied (with the power on) from approximately -15 dB to -70 dB. The adjustment is just above the slug socket and is uncalibrated, the obvious assumption is that you start with minimal coupling and dial it up until you have enough to satisfy the external equipment. The sampler is limited to 5kw on frequencies from 2 to 30 MHz, and to 1kw on signals from 30 MHz to 1 GHz.

A Bird 43/45 Series Slug Reference Table

Power Range 2 - 30 25 - 60 50 - 125 100 - 250 200 - 500 400 - 1000
5W - 5A 5B 5C 5D 5E
10W - 10A 10B 10C 10D 10E
25W - 25A 25B 25C 25D 25E
50W 50H 50A 50B 50C 50D 50E
100W 100H 100A 100B 100C 100D 100E
250W 250H 250A 250B 250C 250D 250E
500W 500H 500A 500B 500C 500D 500E
1000W 1000H 1000A 1000B 1000C 1000D 1000E
2500W 2500H - - - - -
5000W 5000H - - - - -
"K" range slugs have been seen at 1.1 to 1.8 GHz, "L" range slugs have been seen at 1.7 to 2.2 GHz.
While it's not shown as a standard part number I've seen a model number 1500E used as the reverse power slug on a Channel 30 TV transmitter.

Special ordered slugs I've seen:

430-263   100 mw 800-1000 MHz
430-265   500 mw 800-1000 MHz
800-2   2.5 watt 800-950 MHz
801-2   2.5 watt 800-1000 MHz
800-1   1 watt 800-950 MHz
801-1   1 watt 800-1000 MHz


Bird's web site has good manuals for most of their current and discontinued products. Click on the link at the top of the page to go to the Bird web site.

Here are three versions of the Bird 43 wattmeter manual (there may be other manual versions that aren't here). The Bird Model 43 is a product that has been manufactured continuously for over 50 years and relatively unchanged in that time period. Very few manufacturers can make that claim.
Bird 43 Wattmeter Manual  2.8 MB PDF courtesy of K4XL and BAMA. Note that this is the oldest of the three manuals we have and is undated.
Bird 43, 4305, 4431, 4521-27, and 43P Wattmeter Manual   903 kB PDF. This is Instruction Book Part Number 920-43 Rev. D, dated 1998, 2001
Bird 43, 4431, 43P, Series 4300 and 4520 Wattmeter Manual   831 kB PDF courtesy of K4XL and BAMA. This is Instruction Book Part Number 920-43 Rev. E, dated 2004.
Bird 4020-series RF Directional Thruline Power Sensor Instruction Manual  209 kB PDF
4021, 4022, 4024, 4025.
Bird 4021 RF Directional Thruline Power Sensor Instruction Manual  260 kB PDF (used with 4421)
Bird 4022 RF Directional Thruline Power Sensor Instruction Manual  261 kB PDF (used with 4421)
Bird 4304A RF Directional Thruline Wattmeter Instruction Manual  387 kB PDF
Bird 4360 and 4362 "Ham-mate" Wattmeter Manual   1.5 MB PDF. This is the manual for the Bird 4360 HF and 4362 VHF RF Directional Wattmeters (thruline style) that were manufactured for the ham radio market under the name "Ham-Mate". The 4360 is rated at 200w (low range) or 2000 watts, and from 1.8 to 30 MHz. The 4362 is rated at 25w (low) or 250w (high) and from 140 to 180 MHz.
Bird 4380-series RF Power Analyst Instruction Manual  3 MB PDF
The 4381-83-85-87 are 100mW-10kW and the 4382-84-86-88 are 250mW-250kW digital thruline wattmeters. The 4381, 82, 83 and 84 are regular units; the 4385, 87 and 88 are rack mount units.
Bird 4391A Multi-purpose Thruline Wattmeter RF Power Analyst Operating Instructions  214 kB PDF
Bird 4410 Series Wattmeter Manual   We have two scans here: The first is a small file of 258 KB, the second has much better detail but is 2 MB.
This is the model with the range switch option that provides power multiplier factors of 0.1, 0.3, 1, 3, 10, 30 and 100 allowing a single one kilowatt element to provide full scale readings of 0.1 W to 1 KW. Unfortunately this wide measurement range requires the use of specific 4410-series elements. Note that the 4410 series uses a 9V alkaline battery and kills it pretty quickly - approximate battery life is 24 hours of continuous usage. DO NOT LET THE BATTERY LEAK INSIDE THE METER. I know two different folks that have modified the unit for an external batery holder and they remove the battery between uses.
The 4412 uses an internal NiMH rechargeable battery. It may be possible to field upgrade a 4410 to a 4412.
Bird 4421 Thruline RF Power Meter and 4020, 4027A, 4027F, and 4028 series RF Power Sensors Instruction Manual  900 kB PDF
Also includes RS-232 and GPIB interface information.
Bird 6104, 6154, 6156 Termaline Wattmeter Instruction Manual  170 kB PDF
Bird Series 8000 Termaline Coaxial Load Resistor Instruction Manual  547 kB PDF
Bird 8135 Termaline Coaxial Load Resistor Instruction Manual  431 kB PDF
Bird 8141 Termaline Coaxial Load Resistor Instruction Manual  110 kB PDF
Bird 8201 Termaline Coaxial Load Resistor Instruction Manual  175 kB PDF
Bird 8251, 8252, 8255 Termaline Coaxial Load Resistor Operating Manual  520 kB PDF
Bird 8320-series Tenuline Coaxial Attenuator Instruction Manual  495 kB PDF
Bird 8325 Tenuline Coaxial Attenuator Instruction Manual  490 kB PDF
Bird 8327-300 Termaline Coaxial Load Resistor Operating Manual  620 kB PDF
Bird 8400-series Termaline Coaxial Load Resistor Instruction Manual  423 kB PDF
Bird 8833 Termaline Coaxial Load Resistor Instruction Manual  253 kB PDF
Bird 82A Termaline Coaxial Load Resistor Instruction Manual  1 MB PDF
Bird 800 Antenna Tester Operation Manual  1 MB PDF
Bird APM-16 RF Directional Thruline Wattmeter Instruction Manual  550 kB PDF
Bird Termaline Absorption Wattmeters Spec Sheet  280 kB PDF
Power ratings of 2W to 2500W, power scales of 25mW to 2500W, at various frequency ranges.

Construction and Modification Articles and Products

Build an Isolated Tee Sampler for a Bird 43 Wattmeter   Build an IsoTee Sampler for the Bird from a blank slug!   By Kevin Custer W3KKC
A Photo Tour of a Bird Wattmeter Element   By Robert Meister WA1MIK
Ever wonder what's inside one of those elements? Bob took a bad one apart in an attempt to fix it, and took a bunch of photos along the way. And yes, he fixed it!

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This page initially created 30-March-2009 by collecting all of the Bird information away from the Other Manufacturers page and from other pages at this web site, including the Tech Index page.

This web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.