AMATEURTELE.COM
...if your desired language isn't available, the alternative language will be shown...
Nederlands
informatie pagina voor experimenteel radio-onderzoekers
- -
 algemeen
  + for sale
  + adressen
  + fail-gallery
  + press information
  + weblog/news

 apparatuur foto's
  + HP 331A distortion analyser
  + Philips PM2524 multimeter
  + Rigol DS-1054Z
  + Sayrosa 261 frequency counter
  + Schlumberger FS30 / FSM500

 applicaties (pc)
  + UI-View (APRS)

 banden
  + 27Mc
  + FRS
  + LPD
  + PMR

 componenten
  + (E)EPROM
  + crystals
  + resistor coding

 beurzen
  + RF Technology Days 2016

 connectoren
  + 12VDC connector
  + coax connectors
  + TNC connector

 Racal Cougar
  + 0. Racal Cougar
  + 1. introduction
  + 2. compnents
  + 3. assemblies
  + 4. technical
  + 5. modifications
  + 6. data protocol
  + 7. service

 documentatie
  + books
  + FUP1DZ manual
  + jargon
  + Morse code
  + NATO alphabet
  + Q-codes
  + radio notebook

 elektronenbuizen
  + 6H2N-EB / ECC83 / 12AX7
  + algemene informatie
  + ATP4 elektronenbuis
  + elektronenbuis codering
  + elektronenbuizen
  + gloeistroom/-spanning
  + reactiveren/reformeren
  + stabilisatiebuizen

 filters/combiners
  + 23 cm duplex filter
  + Aerial Facilities BPD-410/420-3N
  + Celwave P522 UHF duplexer
  + Hoxin DX-720 diplexer
  + JWX triplexer broadcast/VHF/UHF
  + Kenwood LF-30A LPF
  + Motorola UHF cavity combiner
  + Radiosystem RS460 cavity BPF
  + stub filter [EN]
  + basics: diplexer or duplexer

 legerzenders
  + AM-65/GRC
  + LV-80 RF PA
  + RT-70/GRC
  + SEM antennetuner (AGAT)
  + SEM25 gloeispanning
  + SEM25 transceiver
  + SEM35

 mechanica
  + krimplak
  + schroefdraad
  + verspanen

 meetapparatuur
  + 10/20/30 dB RF attenuator
  + Agilent 8591C
  + BG7TBL noise source
  + Daiwa CN-101L
  + Daiwa CN-801
  + HP P382A verzwapper
  + impedance converter 50/75 Ohm
  + x-tal tester (DIY project)
  + Krohn-Hite 4100 signal generator
  + Marconi 2955A
  + Radiosystem AB dummy load
  + Rigol DSA815-TG
  + Rohde & Schwarz CMT54
  + Rohde & Schwarz CMU200
  + Rohde&Schwarz SMT 02
  + Spinner BN 52-77-66
  + Zetagi DL50 dummyload

 tijdstandaard/GPSDO/oscillator
  + 10 MHz distribution amplifier
  + 10 MHz low pass filter
  + BG7TBL GPSDO
  + Frequency Electronics FE-5680A
  + HP 10811 OCVCXO
  + RS920 10MHz oscillator
  + RS920 OCXO timestandard
  + timestandard (general)
  + tijdstandaard; VE2ZAZ
  + time standard; W5OJM
  + Trimble 34310-T OCVCXO
  + Yaesu FT-8x7 (TC)XO

 meetapparatuur (info)
  + (poor mans) spectrum analyser
  + dummyload
  + frequentieteller
  + functiegenerator
  + meetverzwakker
  + octopus component tester
  + oscillator adjustment
  + staandegolfmeter
  + test- en meetapparatuur

 modificaties
  + Counter 1 MHz input mod.
  + Yaesu FT-897/FT-897D
  + Yaesu MH-48 lock mod

 naslagwerk
  + (coax) kabels coderen
  + APRS
  + AWG wire table
  + coax kabels testen
  + checking, cleaning and overhauling
  + Yaesu FT-8x7 CAT port
  + paneelbouw

 projecten
  + (remote) coax switch
  + afregelen FT-8x7(D)
  + APRS basispost
  + APRS tracker
  + coax switch 1-8
  + condensator microfoon
  + counter prescaler
  + CTCSS module
  + FT-2000 headset
  + FT-2000 remote
  + FUP1DZS meetzender
  + Geloso G.1/1040-A
  + Geroh AKAC019 liermast
  + go-kit
  + go-kit FT-7800
  + headset (Avcomm)
  + hoofdtelefoon versterker PL500
  + Icom IC-25E
  + Kerona AR-301 rotor
  + KLV 400 RF PA ombouw
  + Lineair 400W (Frinear)
  + MFJ-948 antenna tuner
  + parallelle poort controller
  + Pixie CW TX
  + programmeren FT-8x7
  + Samlex SEC 1223 voeding
  + TH-D7E tracker
  + Tinytrak 4
  + uTracer 3+
  + voedingsconnector FT-897
  + VSWR SA meetbrug
  + Yaesu FT-857/897 meter
  + zwaai Alinco DR-135E MkII

 publicaties
  + elektromigratie in filters

 radioapparatuur
  + Ameritron ATR-20 tuner
  + Baofeng UV-5R
  + Diamond X-30N antenna
  + Icom IC-2e
  + Icom IC-7300
  + Kenwood TH-D7E
  + Kenwood TS-830M
  + MFJ-901b antennetuner
  + MFJ-948 antennetuner
  + MFJ-971 antenna tuner
  + QYT KT-8900
  + Triple-P TXU-1256 repeater
  + Wouxun KG-UVD1P
  + Wouxun speakermike
  + Yaesu FT-101E
  + Yaesu FT-1500M
  + Yaesu FT-2000
  + Yaesu FT-7800
  + Yaesu FT-817
  + Yaesu FT-857(D)
  + Yaesu FT-897(D)
  + Yaesu FT-8x7 serie
  + Yaesu FT-991

 reparaties
  + capacitors
  + Geloso 3227 versterker
  + Kenwood TS-830M
  + Lorenz SEM25
  + Yaesu FT-897D

 Rigol DSA815-TG
  + meting: omroepband
  + test: overspraak TG
  + test: TG signaal

 schakelingen
  + elektret microphone
  + Time Domain Reflectometer

 surplus apparatuur
  + Motorola GM950 (70 MHz)
  + Rohill R-2050
  + Teletron/Condor

 telefonie surplus
  + Ericsson F-955
  + Ericsson F-955 modifcations 2017
  + Ericsson RS203/RS2062
  + Nokia NCM30
  + Nokia NNF30
  + Nokia RD72
  + Radiosystem monitoring unit
  + Radiosystem RS922
  + Radiosystem RS923
  + Radiosystem RS950
  + Radiosystem RS951
  + Radiosystems RS963
  + Radiosystems RS9694
  + Rohde & Schwarz CMD53
  + RS925 service box

 theorie
  + aarding
  + antenna rotor
  + antennetuner
  + circulator/isolator
  + snubber diode

 gereedschap
  + Minipro TL866 programmer
  + Velleman VTSSC50N soldering station
  + Yihua 852D+ soldeering station
  + ZD-409 desoldering tweezer
  + ZD-915 desoldering station

 werkplek
  + soldering
  + workshop tips

 EMC/EMI
  + decoupling capacitors

 veiligheid
  + Beryllium oxide
  + EM veldsterkte
  + radioactiviteit
  + harardous radiation?

 overig
  + SV500 radiation meter


Radiosystem AB dummy load

permalink: http://www.amateurtele.com/index.php?artikel=216&id=#936
A long time ago I bought a Radio System AB (Ericsson) 50 Ohms dummy load with N-connector for testing purposes. It’s a dummy load from the former NMT450 mobile phone network. It’s likely these dummy load were fitted to the front of the RS460 cavity band pass filter. The footprint, paint color and structure and four holes of the dummy load match perfectly to the unpainted square on the front of the RS460 filter boxes. Possibly the dummy load were used to dissipate sideband energy…
The nice thing about these dummy loads it equipped with a BNC test point. The internal chip resistor has a test point which is connected to the BNC socket. This is for example convenient for frequency measurements. The RF power is dissipated into the chip resistor and a relative low power test signal can be used to feed a frequency counter. I guess the chip resistor can handle at least 100 Watts of RF power when fitted to a heatsink.

image is loading...


The dummy load is used for seven years now. And since I bought a Rigol DSA815-TG spectrum analyzer recently, this is a nice opportunity to determine the power reduction at the test point. I normalized the test setup and measured the loss. I would expect the signal reduction is linear, but I was wrong. The signal reduction of the test point is logarithmic. The lower the frequency, the more the signal reduction at the test point and vice versa. Luckily I updated the firmware of the Rigol DSA815-TG spectrum analyzer and has now the option to show the frequency scale logarithmic instead of linear. Therefore the bent signal reduction line on the screen appears quite linear! Using the CSV export function I exported the trace information to Microsoft Excel. After fiddling with the graph function I added a “trend” line that fits very nice onto the trace of the measurement. There’s a convenient option to show the formula of the trend line. Since the trend line fits very well it’s safe to say that the formula fits therefore also the signal reduction. The determined formula is this: [dB] = (7,527 × f [MHz])-72,44. If a frequency in MHz is multiplied with 7,527 and the result is reduced with 72,44, the answer is the signal reduction in dB relative to the input.

image is loading...

image is loading...


For convenience I calculated the signal reduction for the regular ham bands. The results are shown below. The dummy load is used for approximately 460 MHz and should work fine up to 3 GHz. I cannot verify this since my equipment can measure “only” op to 1,5 GHz. Assuming the formula fits until 10 GHz, the numbers should fit. But it’s possible the dummy load will behave different at “extreme” frequencies (above 3 GHz). So beware not to blow up the input of your measurement devices. Normally a spectrum analyzer is very sensitive for overload at the input. Be sure to calculate/verify the test point signal strength at certain frequencies and input power. For example the Rigol DSA815-TG can handle +20dBm at max. If a HF transmitter (1,8…28 MHz) is tested, the least signal reduction at the test point is -47,4 dB. The maximum signal at the input port if the dummy load is +67,4 dBm. The maximum input power is therefore 5.495 Watts. Since the dummy load can handle approximately 100 Watts, it’s safe to say that your DSA815 won’t be damaged testing an 100 Watts HF transmitter. At 435 MHz the signal reduction is 26,7 dB. The maximum input is +20 dBm, therefore the maximum power input is +20 dBm + 26,7 dB = +46,7 dBm = 46,8 W! There are several 70 cm transceivers and amplifiers delivering more than 50 Watts, so beware that this could (or will?!) damage the DSA815 applying more than 46,8 Watts to the dummy load input.

1,8 MHz = -68,0 dB
3,5 MHz = -63,0 dB
5,3 MHz = -59,9 dB
7 MHz = -57,8 dB
10 MHz = -55,1 dB
14 MHz = -53,6 dB
18 MHz = -50,7 dB
21 MHz = -49,5 dB
25 MHz = -48,2 dB
28 MHz = -47,4 dB
50 MHz = -43,0 dB
145 MHz = -35,0 dB
435 MHz = -26,7 dB
1,3 GHz = -18,47
2,3 GHz = -14,2 dB*
3,4 GHz = -11,2 dB *
5,8 GHz = -7,2 dB *
10,0 GHz = -3,1 dB *

* These numbers are based on the formula and not verified in a real world measurement.

open de afdrukbare pagina door hier te klikken


AmateurTele.com - © 1984...2017 - Build: 20170615c