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FT102 RESTORATION This WEB Site is Devoted to Maintaining Hybrid ( Transistor/Valve
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Sunday 9th March 08
| SAFETY IS FIRST Please read the Safety information before attempting any repair or restoration. First thing always is Safety. Check the power cable condition & fuse. The Mains fuse should be a 3Amp 3AG slow blow in the FT102 when using on 240 volts. Powering it up I found the receiver to be quite lively on the 80 & 160M bands, & down on bands above 17M. The 40M band also seemed down but 20 & 30M were fine. The problem was the same whether the preamp was turned on or off. The first thing I did was to use a calibrated signal generator & test all bands & found that some bands were down including the 40M band that was some 10dB down compared to 20M. I decided to go through the RF filter alignment first to make sure that the filters were aligned correctly just incase they had been fiddled. After aligning the filters the problem remained, so I decided to break the RF board into various sections & try & find the problem. I fed a RF signal generator into the mixer directly & checked the radio on all bands. The Radio seemed fine, but it was only after comparing it to another FT102 that I found the mixer gain seemed low. I then tested the Local oscillator input & it seemed fine at around 0dBm on each band & dropping a couple dB on the 10M band. It was only then that I decided that the mixer was the problem & decided to change the 2SK125 FET's. On turning the Radio back on all was fixed, & one of the FET's was found to be faulty. This is apparently a common problem in the RF preamplifier of the FT102, but the mixer FET's had not been mentioned as a possible cause to receiver gain problems. The first thing that we do with any Radio Restoration after we have checked that the Radio is safe, is to give the outside cabinets & front panel a basic clean to get some of the grime off of it. A more thorough clean can be done if required by removing the knobs & using a foam glass cleaner, ( CRC Glass Cleaner ) & lint free tissues to clean without damage to the paint. This type of cleaner tends to put the dirt out & will not damage the paint. Be extremely careful with the paint on the front panel of the FT102 as it appears to chip very easily. Remove the covers & clean any dust from inside with a paint brush & Vacuume Cleaner. Be very careful with front panels, pots, switches, knobs etc as there does no appear to be any spare parts available from Yaesu if you damage or break them. These things are becoming collectors items so it is best to try & keep it as close to original as possible. Factory modifications are fine as these fixed minor problems, but try not to change the operation of the Radio from original. Don't overdo restoration as over painting things doesn't look original or old. A large number of faults or intermittent's can be traced to dirt in pots & switches. Use a suitable contact cleaner lubricant ( Electrolube EML ) & spray inside all the pots, trim pots, & switches. It is also suggested that you remove any covers over relays & try & clean the contacts. Make sure that you use a lubricating cleaner specifically designed for the job else you risk permanently damaging pots. Check the VFO for tightness & any lumpy ness as this could be a sign that the VFO bearing need cleaning & lubricating. I have taken a number of Yaesu VFO apart & found the bearing holder with score marks in side. This causes the lumpiness & can be improved by cleaning & re greasing the bearing holder. It is best when reassembling the VFO to just finger tighten the front bearing adjustment until the VFO is very smooth& rotates easily. Use a tamper locking seal when you are happy with the adjustment to lock the nut so it won't come loose with use. I have found many Radios with this adjustment over tight. While you have the VFO out replace any of the light globes that maybe blown.
PLL LOCAL COIL ALIGNMENT I did this by using a Spectrum Analyzer attached to the test points which made the alignment easy.
PLL VCV I just followed the alignment in the manual & used a digital multimeter to set the VCO voltages. There is a mistake in the manual, L4006 should be set to 2V at 7.5MHz not 6V. They are a bit difficult to get exact as the coils use a square section rubber band to hold the cores in place with vibration, so adjustment is quite course on the higher bands & impossible to make exactly as per the manual.
SECOND & THIRD LOCAL OSCILLATOR ALIGNMENT I did as per the manual but used the Spectrum Analyzer to peak the coils.
1.875MHz TRAP ALIGNMENT This was a difficult alignment as initially I just could not hear any difference when adjusting TC4004. I then found that the adjustment was quite critical with the trimmer cap, & eventually null ed the carrier on 1875kHz to a lower level. I was however never able to null it completely.
RF UNIT ALIGNMENT This is quite a difficult alignment & requires a large amount of time to confirm that the alignment is correct. I used the Mini-Kits DDS SWEEP generator Kit along with a Spectrum Analyzer to do the alignment. I set the RF output from the SWEEP Generator to -30dBm & fed it into J1001. The RF out RCA socket on the rear of the Radio was then fed to the Spectrum Analyzer.I was not able to align the 10.0-10.5MHz filter correctly & have to revisit it. The coils would only peak the output not flatten the response. PRESELECTOR ALIGNMENT The alignment of this is straight forward as per the manual. The only issue I could find is that both trimmer capacitors TC1001 & 1002 seemed to be in full mesh after the alignment. I may have to revisit this to confirm on another Radio to see if this is normal. FIRST MIXER ALIGNMENT This alignment is straight forward as per the manual. 8.215MHz IF TRAP ALIGNMENT This alignment is straight forward as per the manual. IF UNIT ALIGNMENT This alignment is straight forward as per the manual, although it is near impossible to get to T2018. I would not worry about it as its probable that no one else has touched it anyway. NOISE BLANKER ALIGNMENT This alignment is straight forward as per the manual. S METER ALIGNMENT The meter in most old Radios are not all that accurate. The meter when aligned to S9 is quite close on most bands within 0.5 S units. I usually set the S meter trim pots, the zero adjustment at S3 & the S9 setting at +20dB/S9 to get a better reading over the range. I was not able to get good results with the FT102 & decided to set the Zero setting trimpot ( VR2002 for S3 ) & S9 setting trimpot ( VR2003 for S9 ). This gave good results between S1 & S9 but a +20dB increase over S9 measured +35dB/S9 on the meter. Both trimpots interact so you will have to go over the settings many times to get good results. Set your RF signal generator for -73dBm for the S9 setting & use a 20dB attenuator inline for -93dBm for the S3 setting. The Marker should read around +20dB/S9 on most bands except 10M which I got around S9. The marker level will of course depend on the S meter alignment. ALC METER ALIGNMENT TO BE UPDATED SOON RF PROCESSOR W TOUCHUP PAINT I
WANTED ITEMS None at this time. REPLACEMENT PARTS Please email me for prices on the Parts listed below Relay Catalogue Download
Section15
Includes Relays for Yaesu FT102 PA0PGA's
FT-102-Survival Guide (Rev.3).pdf (12.3MB)
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