19khz Pilot filter options?

[radiowavesokc]

Hi.  I have a station that still utilizes an old Orban 8100XT/2 processor.  I'd like to utilize a MicroRDS unit for this station if possible.  Here's the challenge:  How can I extract the 19khz pilot so the MicroRDS can lock onto it?  Is there a simple filter for this, or is filtering fairly difficult?

Thanks,

PR

[Jan]

If pilot is not accessible anywhere (MPX only), you have 3 options:

• Use PIRA32
• Leave it unsynchronized (suitability depends on application)
• Use the pilot filter below

Pilot filter

Input MPX level at least 1.2 Vpp. Recovered pilot is available at PLT. Signal /SNC goes low if pilot is detected.

Part list:
IC4 – LM567
IC5 – TLC272 or any opamp
L2 – 09P-152J (1.5 mH)

R17 – 2k
R19, R26 – 10k
R15, R18 – 15k
R16, R20, R21 – 33k
R28 – trimmer 5k

C6, C12, C24 – 100n (C)
C8 – 10u (E)
C9 – 100u (E)
C25 – 4n7 (P)
C21 – 3n3 (P)
C22 – 220n (P)
C23, C29 – 1n (C)
C27 – 47n (5%, P)
C28 – 330p (C)

Adjustment:
With no input signal connected, adjust 19 kHz (+/- 100 Hz) on PLT using trimmer R28. Alternatively connect the MPX to input and adjust the R28 to the position where /SNC goes low.

[Ross]

Hi Jan,

I was going to make up a couple of these 19Khz Pilot Filters and looking at the Circuit I noticed in your parts list

C29 & C23 are listed as " in (C) " ie No Capacitor Value given.

Any thoughts what these caps should be ?

Thanks,

Ross 

[Jan]

1 nF ceramic type