#14 Icom IC-735 PLL and VCO repair and alignment with back ground information

Repair and alignment of PLL and VCO circuit and basic information on PLL and VCO function.

[@grantfullen9559]

These are the best radio repair videos. You explain things very well. I learn allot of things . Keep up the GREAT work.

[@TRXLab]

Thanks for your feed-back :-)

[@waynecarlson3736]

This is VERY informative you explain everything before and after you do anything. THANK YOU PETER

[@TRXLab]

Glad that you like it although especially in the early videos my English is even much more worth than it is still today.. 73

[@emylrmm]

@@TRXLab your English is quite good enough and easily understood

[@cwqrp]

TNX sharing detailed PLL repair, I will go for it, later this year, Just bought an IC-735, fine transceiver, and PLL on 40m, VCO1, is not OK, too much phase noise, and not always stable. Of course, I will replace all capacitors. Have to wait for a good free time period, and for the parts, so will happen in December 2020. WIll include light repair and battery repair, so it will start as new again. 73 PE1FJN

[@blpblp-tj7ux]

How is the progress?

[@cwqrp]

@@blpblp-tj7ux it went perfect, radio is now like new😃👍

[@RagnarEE]

This I will definitively check on my 735. Thanks Peter. Superb video again :D

[@TRXLab]

Thanks for watching. All the best 73

[@jpmiller8098]

I worked on a PLL circuit one time that mixed two PLLs together. Both PLLs used the same reference oscillator. As it turned out if the reference oscillator drifted the two PLLs would drift in opposite directions such that the resulting frequency did not change much.

[@emylrmm]

0.001Hz in 100MHz converts to a stability of 0.01 ppb, and so I think your Racal Dana frequency counter has a Rubidium Vapor oscillator for its external time base. Impressive!

[@bobclarie]

Thanks for your video, we appreciate your efforts. I have an IC-735. The receive audio on 40 meters becomes distorted/garbled after it warms up for about 30+ minutes. According to my research, it looks like I need to replace C37, C45, C52, C59 & C138. These are ceramic trimmer caps: two 12pf VCO (white), two 6pf VCO (red), and one 6pf ref osc (red). two questions: where can I acquire these caps, and, what equipment would be required to realign after replacing? Thanks '73 Bob

[@TRXLab]

+bobclarie Hi Bob, thanks for watching! Well you nee a good DMM and a precise frequency counter to adjust the radio after repair. Sorry I don't know where you can by this parts in the US. If needed I can give you a supplier in Europe. 73

[@budleyca1]

Good video..I found that when you put the pa deck back on, the frequency will shift. If you have a good ear you can adjust c138 so that it is either a little hi or low and then put the pa deck back on and check for zero beat, just takes a little bit of trial and error but you can get it to zero beat and be stable.

[@TRXLab]

Yes you are right that could be one way to handle it. Thanks for you feed back!

[@Yavor54]

My IC-735 has the strangest PLL unlock issue: Between 15 and 22mhz, the RX is dead. Cold, it will work and then it finally unlocks 10 minutes later. 14 and 7 mhz bands are stable, but 28 mhz also gets unstable occasionally. Has anyone seen this with the 735 before? All alignment specs are perfect when it is locking up.

[@cwqrp]

One question, do you have an address where to find the ceramic trimming tool?,, I have plastic ones, not good for capacitors.. TNX for tip.

[@emylrmm]

fascinating. thanks for this video

[@shelbyroberston2882]

I have a Icom 735 needs repair? do you have a recommendation ? I live in Niagara Falls, NY USA

[@blpblp-tj7ux]

this video has been so helpful...at about 25:00 you're taking a millivolt reading from pin 5 of IC17 with the URV 35...what is the probe impedance in this case?

[@TRXLab]

That is the original R&S probe which has as far as I remember right about 100KOhm

[@Okruszek81]

I have same problem with my 735, how much roughly cost repair? Deaf around every 100khz and bad modulation.

[@ChrisWilson5006]

I look forward to your videos, they are very helpful. In the manual for setting the new trimmers it states mode should be AM, but you were in SSB mode, will that make much difference? Please keep the videos coming! All the best.

[@TRXLab]

As far as I remember I did the adjustments in AM. But anyway, it will not be a Big differnce as the Tuning voltige should bei the same on Am and SSB. The PLL should lock on both. Tranks Fr. You Feed back.

[@richklestinez1906]

When you adjust the oscillator cans what tuning tool do you use. Great videos, keep them going.

[@TRXLab]

Hi Rich, it is a ceramic screwdriver. Thanks for watching 73

[@alessandrozax]

Very Good, what kind of "white fixative" has been used at 18:38 !? ...seems candle wax..or not .

[@TRXLab]

Hi Alessandro, that is paraffin. Thanks for watching 73

[@bmn_nc]

Very good! I hope you make the parts and board available to friends in US with IC-735. TNX, Buddy N.

[@TRXLab]

Hi Buddy, I'm sorry I'm not selling parts and pcb's. Thanks for watching 73

[@G0NMY]

Thank you for sharing this video it was very informative, however, I noticed on the last two VCO trimmer capacitor adjustments the radio was in USB mode and not AM mode. Will that not make the carrier frequency higher than it should be? I assume you checked it and corrected it off video hi hi. Many thanks for the video I really enjoyed it. 73 Mark

[@TRXLab]

Hi Mark, yes you are right I noted it during editing and corrected it off camera. Thanks for watching 73

[@gatocesk]

Very Good....thanks

[@Manja3012]

Hallo, erstmal ein super Video mit viel Informationen. Leider habe ich das Problem, dass schon beim ersten Punkt "Tuner Voltage" statt 1,2 Volt 12,9mV bei 7,9999 Mhz AM nur vorhanden sind und bei 8,0000 AM nur 1,736 Volt statt 2,5 Volt anliegen. Im Manual steht was von L47 nachstellen, aber wie ich das sehe ist es ja die Spule in der kleinen Kisten "subpll", da kann man ja nicht nachstellen oder befinde ich mich auf dem falschen weg?

[@TRXLab]

+Manja Schuster Hi Manja, vielen Dank fürs vorbeischauen. Soweit ich mich erinnere wird die Spule im Sub PLL auseinandergezogen bzw. zusammengedrückt um die Spanunng zu verändern. Hoffe die Antwort hilft. viele Grüße und 73

[@Manja3012]

+TRXBench Vielen Dank, sowas ähnliches hatte ich mir schon gedacht. Dachte das ich auf dem falschen Weg wäre, weil es ja alles ein bisschen vergossen ist. Nur neben bei als Info, mein Fehler ist das auf allen Bänder immer die letzen ca. 100Hz tot sind, z.B. 28.086,6-28.098,4 und das zieht sich so weiter vom 160m bis 10m. Bin ich da auf der richtigen Spur oder ist das nur ein Symptom eines anderen Fehlers?

[@TRXLab]

+Manja Schuster ja du bist höchstwahrscheinlich auf dem richtigen Weg. 73

[@karisyrjanen1354]

Where to get those 6pf ceramic trimmers?? Kari OH5YW

[@TRXLab]

Kari Syrjänen Hi Kari, you can get it here: www.box73.de/index.php?cPath=82_107_170

[@13AT218]

Hallo, ich bin gerade auf dieses alte Video gestossen weil ich auch so einen TRX mit genau dem Problem auf dem Tisch habe. Laut Service Manual sind es 6pF und 10pF Trimmer. Leider kann ich die 6pF nirgends finden. Kannst du mir eine Quelle hier in Deutschland nennen? oder kann man einfach für alle Kondensatoren den gleichen Wert nehmen? Sie werden ja sowieso eingestellt... Danke und Gruß!

[@TRXLab]

www.box73.de/index.php?cPath=82_107_178 Schau Mal hier

[@13AT218]

@@TRXLab Vielen Dank! An die habe ich garnicht gedacht! Schon bestellt! ;-) 73 und weiter so!

[@stargazer7644]

This was my first HF radio. I hated it. Terrible radio. Sold it and bought a used Kenwood TS440. Much happier.

[@jamesdoyle6839]

just did a pll repair on a ic-3200a dual band mobile, no pll...turned out to be conductive wax ! never seen that before..ts-440 yes.. never wax.

[@TRXLab]

Conductive wax wow that is interesting....Thanks for the hint and thanks for watching 73

[@khaledsalah1986]

What if the voltage does not change? Where is the problem then?

[@josesantana8951]

Greetings my friend. Where can i buy those capacitors and parts numbers. Thank you.

[@TRXLab]

you'll get those caps from any electronic dealer in your neighbourhood or of course from ICOM..

[@baghdadiabdellatif1581]

Thank you

[@pekkalahdensalo9294]

Pse info ceramic trimmers. 10pf? Where ,I can buu iy?

[@TRXLab]

Pekka Lahdensalo Hi Pekka, you have an e-mail... 73's

[@smaug00000]

TRXBench I have the same question. Where can I find suitable replacements?

[@hl5bno]

thanks. good.

[@TRXLab]

+daeyoung kim Hi, Thank you for watching and comment

[@emylrmm]

if the local oscillator drifts by say 30Hz up or down as the transceiver warms and cools, I doubt it would be noticed by either operator during a QSO. This was probably the mindset of the engineers at ICOM. Why put in an expensive OCXO if one isn't justified in the product application.

[@PeterWalkerHP16c]

I would not have guessed that trimmers degrade that much.

[@TRXLab]

+Peter Walker Yes really bad degrade and producing odd behaviour..

[@wakkowarner7391]

Can they stop an oscillator working completey?

[@cqdx1677]

Why radio producers use cheap plastic trimmer capacitors instead of ceramic ones? They save how many dollars per radio:(((

[@TRXLab]

yeah, it is all about money...

[@jacknifedbl]

humm i made have to upgrade to t tem compensate crystal...

[@stevenA44]

OMG!! STOP saying UH UH UH!! It's annoying as hell! LEARN what you are going to say before making a video!!

[@michaelw7053]

Cut the man some slack! I doubt English is a primary language for him. As annoying as you believe it to be, how annoying would it be in Dutch or German! Relax and be glad the man took the time to go into the detail that you hate but at the same time desperately need.

[@stevenA44]

@@michaelw7053 I WASN'T "talking" to you dumbass! Just STFU and mind your OWN GD business!! And I DON'T desperately need this, nor do I NEED it at all!!