Hello guys i have a 142gtl board is a PC-385AG i have sams alignment procedure and im stuck at getting a frequency reading @tp 3 thanks.
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142 Gtl Aligment Issues
- Thread starter kaos513
- Start date
Yeah tried that alignment as well get stuck at tp3 i have my grabber on r101 as well, counter doesnt read it and makes humming noise for some reason .
TP3 is the main 7.8MHz stuff for the AN612 and conversion - so if it failed - at TP3 no signal - suspect TR22 1675 and associated Diodes and support hardware - or else the MODE selector especially if AM is dead - all modes dead - in any case - means you lost your 2nd Conversion signal.
IT uses that jumpered coax thingy - that routes around FT3.
IF you Need a schematic - it's not the best but you can CLICK HERE as you need. It's a JPG so it's easily viewed by most browsers.
:+> Andy <+:
IT uses that jumpered coax thingy - that routes around FT3.
IF you Need a schematic - it's not the best but you can CLICK HERE as you need. It's a JPG so it's easily viewed by most browsers.
:+> Andy <+:
the signal here is just too weak for your counter to read.
very common problem in this chassis.
you can get one of those wideband RF amplifiers to put in line, or you can use the 1K tone method where you tune the VCO coils very accurately, then inject a very accurate 1000hz tone into the mic while in SSB mode with the counter coupled to the antenna jack of the radio. (i usually just disconnect TP7 and TP8 and then connect the counter directly to the antenna jack)
then, transmit the tone on USB channel 20 and tune the USB IF adjustment for 27.206000 mhz.
switch to LSB and tune that can for 27.204000 mhz.
AM is easy and just tuned with a deadkey for 27.205000mhz.
now your IF cans are all aligned!
just be careful not to key the radio into the freq counter with TP7 and TP8 connected!
LC
very common problem in this chassis.
you can get one of those wideband RF amplifiers to put in line, or you can use the 1K tone method where you tune the VCO coils very accurately, then inject a very accurate 1000hz tone into the mic while in SSB mode with the counter coupled to the antenna jack of the radio. (i usually just disconnect TP7 and TP8 and then connect the counter directly to the antenna jack)
then, transmit the tone on USB channel 20 and tune the USB IF adjustment for 27.206000 mhz.
switch to LSB and tune that can for 27.204000 mhz.
AM is easy and just tuned with a deadkey for 27.205000mhz.
now your IF cans are all aligned!
just be careful not to key the radio into the freq counter with TP7 and TP8 connected!
LC
i was thinking the same i saw one of mikes radio repair where he talks about the amplifer for low frequency.
Great what im going to do is make aligator clips or grabbers one end and bnc connector onbthe other then connect it to my signal gen then to a speaker see if that helps.
If the preamp has a 50-ohm input you may have problems connecting its input jack direcly to high-impedance test points in the radio. It's like taking a 50-ohm resistor and soldering it from the test point to ground. Most of those points in the radio will be disrupted by putting too low a resistance in parallel with it.
If you can get a 10-to-one 'scope-type probe, this will reduce the circuit loading that disrupts the radio when you touch a probe to it.
Just one problem. This reduces the sensitivity of the counter farther still. Might work with a 10-to-1 probe feeding into the preamp.
73
If you can get a 10-to-one 'scope-type probe, this will reduce the circuit loading that disrupts the radio when you touch a probe to it.
Just one problem. This reduces the sensitivity of the counter farther still. Might work with a 10-to-1 probe feeding into the preamp.
73