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G8MNY  > TECHNI   21.11.21 09:50l 157 Lines 7334 Bytes #999 (0) @ WW
BID : 53671_GB7CIP
Read: GUEST
Subj: RTT Comms Test Set Use
Path: PI8DRE<PI8CDR<DB0RES<ON0AR<OZ5BBS<CX2SA<ZL2BAU<EI2GYB<GB7CIP
Sent: 211121/0831Z @:GB7CIP.#32.GBR.EURO #:53671 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

By G8MNY                             (Update Mar 21)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

My now all fully working properly, extensively modified & calibrated, the
"Radio Telephony Test Systems" test set was made in Feltham UK in 1987-9, &
although old it can do quite a lot...
       ___________________________________________________________
      /                                                          /|
     /                                                          / |
  /  |
  /__________________________________________________________/  |
 ޳Ŀ  |
 ޳ĿĿĿĿĿ  |
 ޳ \ AF   \SINAD5 3 99 9 9 9 0 0  \MOD   \POWER  |
 ޳__\______\_________________________\______\ ___  |
o   _         _   Oven    _   _       Lock         _  Rx  |
_   (_)_______(_)         () (_)    o    ! ! !   (_)   _ |
AFo  _ ________    _          _      _     _        .-.     |
in@ (_)  o  o  (_)  (_) ! !   =(_)   =(_)   (_)   o  ( o ) RF /
  CTCSS Lis Vol MOD    _    SIG GEN FREQ    _  _   _'-'_ in/
  1234   LS   12    ()   1 2 34 5 6 7   () () ()=() /
  ٳ/
   ~~޲~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~޲~~

SPECIFICATION
RF Input          N socket 50 20dB Load atten. 1kW peak, 50W continuous
Power Meter       1-300W, 6 ranges (RF detection for Counter & Rx mode)
Frequency Counter 9 digit 1Hz-540MHz in 3 gate times & 10s averaging to 1Hz
Freq Reference    Accuracy < 1/10^7/month, internal Xtal Oven & warming LED
Signal Generator  PLL 100Hz steps from 10 - 539.9999MHz, O/P -13dBm (50mV)
Sig Gen Harmonics >-20dBc, Typically >-30dBc
Gen Attenuator    10x1dB & 8x10dB for 1.7uV-50mV, 40dB lower via Load
Pilot tone(CTCSS) PLL 20-999.9Hz in 0.1Hz steps, Mod Level & Rx Counter readout
AF Modulation     AF Osc 100Hz-15.9kHz or ext, Level adjustable
Ext Mod/AF out    Needs >1V in, or gives 0-4V RMS AF out, 600 BNC
Xtal/IF           455kHz & 10.7MHz in built & ext Xtal socket & osc O/P BNC
AF Meter          Bal/floating 3mV-10V & dBs 8 ranges, 11Hz-27kHz -3dB
SINAD meter       Auto level, 1kHz Notch, 0 to -20dB/100-0% Noise & Distortion
Automatic Rx      Scans 2MHz->1GHz, 100mW-300W Load input, up to 60dB S/N
RF & IF O/Ps      Rear BNCs for RF & 450-470kHz IF
Rx AF Filters     Comms -3dB 300Hz-3kHz, or HiFi -3dB 50Hz-15kHz
Modulation meter  Auto Rx. +/- peak, AM 50/100%, FM 5/100kHz, PM 2/5 Rad
Monitor Amp & LS  Vol & 1W for Listening to: AF in, SINAD, AF Osc, & Rx
Power             AC IEC Mains input 230V/115 @ 60W, or XLR for 12V DC @ 5A
Weight            24kg in flight case

Tx MEASUREMENTS
===============
1/ Tx connected to N socket of the 300W Load atten input you can measure...

Ŀ Ŀ  Ŀ  a) Tx power 0.1-300W with 6 power scales.
PSUĴTx>Ĵ Test set
     b) Frequency 1Hz - 540MHz to 1Hz res (1 or 10s gate).
      Mic
                         c) FM Dev 0-5kHz, 0-100kHz (AM Mod 0-50%, 0-100%).

                         d) CTCSS frequency, & Dev @-20dB (e.g. max +/-250Hz?)

                         e) Hear the AM/FM modulation on Test set's LS.


2/ Tx connected to N socket of the 300W Load atten input you can measure...

Ŀ Ŀ  Ŀ            a) With external spectrum analyser after
PSUĴTx>Ĵ Test set               the 20dB high power atten & 20dB splitter
                  (40dB less), but the power meter's diode
      Mic  BNCĿ    load increases some of the harmonics!
          LinkSpectrum Analyser
        @-40dB  b) Other Tx spuri can also be safely seen.
                or a Scope on HF

3/ Tx connected to N socket of the 300W Load atten input you can measure...

Ŀ Ŀ  Ŀ            a) With a scope connected to IF output
PSUĴTx>Ĵ Test set>ĿRx          & 2nd Beam or Trigger from Rx AM Mod
     AM          then AM modulation lineararity, or
      Mic   IF Ŀ mod         any AM Hum can be seen.
           out>Scope 
                

4/ With Rx AF mod BNC patched to AF input banana sockets on test set.

Ŀ Ŀ  Ŀ  a) AM/FM Tx Signal Noise to <70dB can be measured
PSUĴTx>Ĵ Test set     via the Comms or Hifi filters.
   
      Mic       >   b) Hear the AM/FM Tx noise on Test set's LS.
                Rx   AF


5/ Mod AF Osc BNC output patched to Mic with a suitable atten/pot.

Ŀ Ŀ  Ŀ  a) AM/FM Tx Distortion can be measured on SINAD meter
PSUĴTx>Ĵ Test set     & hear the notched distortion on Test set's LS.
   
    Mic<  >   b) AM/FM modulation frequency response 100Hz-15.9kHz.
          AFMod  Rx  AF     Read on AF meter's dB scale. (e.g. -40dB @ 4kHz??)
          1kHz              SSB response only done to the power meter.

                         c) Single Sideband actual Tx freq measured.

Rx MEASUREMENTS
===============
6/ Rx patched to load N, or BNC after stepped atten. for 40dB more (50mW max).

Ŀ Ŀ  Ŀ  a) AM/FM Rx can tested for freq error & selectivity
PSUĴRx<Ĵ Test set     with siggen set to correct or off +/- frequency.
   
            Mod on/off   b) Rx CTCSS recognition, dev & sensitivity checks,
                            with & without comms mod present.

                         c) Rx S meter calibration checks. (S9+20dB HAHA!)


7/ Rx patched to load N, & Rx LS to AF input banana sockets on test set.

Ŀ Ŀ  Ŀ  a) AM/FM Rx Frequency response seen on dB scale.
PSUĴRx<Ĵ Test set
     b) AM/FM Rx Distortion @ 1kHz on SINAD meter.
     LS>AF  1kH or
             .1-15.9kHz  c) AM/FM sensitivity in uV/dBm, siggen set & 1kHz
                            modulation for 12dB S/N.

                         d) AM/FM max S/Noise (hum etc).

Sinad meter is used for best Rx S/N sensitivity & FM discriminator adjustments.
For that, 5 turns of the LS lead on a ferrite ring, stops it being an added
aerial on weak test signals! RF & DC leads may need the same treatment!


CONCLUSION
==========
All of the above 20 tests, also permit rig adjustments to improve things.

With SSB kit AM mode has to be used to the Rx only. But SSB Tx 2 tone tests can
be done using CTCSS & beating AF osc (e.g. 0.8 & 1kHz) from mon LS to the mic &
scoping the Tx RF envolope (200Hz) beat note on a seperate dummy load.

So a useful lab or /P test set. A one stop shop for all rigs, when taken to my
local club's regular test & fixit evenings.



See my tech Buls on "RTT Comms Test Set", Analyser Takeda Riken TR4122B", "AF
Waveform Generator (RS)", "RTT Mod Meter (100)", "FeelTeck Dual DDS Osc FY6600
-60M", "Marconi Distortion Meter TF2337","Marconi 2019A Sig Gen"," Systron
Donner 1702 Sig Gen" "Marconi Counter Type 2432A", "198kHz Off Air Standard",
"Comparing Off Air Freq Standards", "Off Air Lock for Ref Osc", & "Scope RF
Trick".


Why don't U send an interesting bul?

73 de John, G8MNY @ GB7CIP


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