24 May 2010

Worse than the H1N1... ceramic filter pandemic

Well, it could be a false alarm (pun intended) but lately I have been getting more and more rigs for repairs, and from diferent manufacturers, with bad Toko black ceramic filters (6 and 9 kHz by now)

I have fixed three rigs in the last few weeks with this problem, two Yaesu FT-897 and one Kenwood TS-2000. Symptoms could range from lower sensitivity, to cracking noises and, usually, you have both. There is also an interesting effect, at least on FT-897s, which is that they receive in DSB instead of SSB when filter fails.

I have opened one filter and it had some greenish looking residue on it, so I guess sealing had failed and moisture did the dirty job.

I would be interested in hearing other people experiences with those small "BLACK NOISIES" (*) (remember you saw it first here, (c) EB5AGV ;-) )

Best regards,

JOSE

(*) the equivalent to "BLACK BEAUTIES" caps in old boatanchors!

24 comments:

Anonymous said...

Thanks for the info, Jose. Recently acquired a Yaesu 7800, and a Kenwood TS-480 SAT. Will now be wary of that happening to my rigs.

73,
Larry, WA9GUU

Anonymous said...

This happened to my FT857D. In that rig, the schematic shows that the diode DC switching voltage is applied to the Toko AM ceramic filter, although the Toko data sheet says that a DC blocking capacitor should be used. The problem is not the filter, it's that the rig design overlooked the need to avoid applying DC voltage to the filter. I simply added 0.01 microF capacitors at the input and output, and that cured the problem without having to replace the filter. From what I've heard, if this is left unchecked then the filter deteriorates and has to be replaced too. The filter is cheap, but replacing it (as you know) may take a lot of labor.
I've posted a file describing that repair to the Yahoo FT857D group.
73
Darrel, aa7fv.

Anonymous said...

Hola José. Mi FT-857D sufre de el mismo defecto. Empezó con muchos estáticos en el receptor, y en el audio del transmisión, y ahora, recibe DSB con muy poca sensibilidad, y en TX parecen haber desapárecido los estáticos!. El CF 1005 parece haberse definitivamente estropeado, así que he encargado el repuesto, y lo cambiaré. Si os interesa posteré mis resultados. Saludos. Leandro.
LU8AOI

Anonymous said...

Finally, The replacement of CF1005 cure the problem in my FT-857D. I've to wait the filter one month to arrive to this latitudes, and change it took me like one our (between remove the board, and reasemble all together). I didn't make the modification that Darrel propose (wich is also recomended in the datasheets of the filter, but only in the output lead), so let's see how much takes to repeat the failure (hopefuly, a very long time).
73s, Leandro LU8AOI

Jose EB5AGV said...

Hello Leandro,

Thanks for letting us know about your experience. I have so far replaced three damaged filters in different rigs and I am afraid lots more are on its way.

73 JOSE EB5AGV

Anonymous said...

Hola José:
Encontré el mismo problema en un TS-2000, los filtros cerámicos CF1, CF2, CF3 y CF4 presentan una baja resistencia a tierra (aprox 90 ohms) Probé a sustituirlos con otros Murata y funciona bien, pero son de diferente tamaño. Pedí ya nuevos filtros a Kenwood y espero los nuevos no den problemas. (En mas de 20 años de reparar radios únicamente he cambiado un filtro cerámico) 73´s Guillermo XE1GFF

Anonymous said...

Good afternoon Jose.
Following your tips replaces all of my ceramic filters FT 857, including CFJ455K14, bought all direct yaesu USA. Solved the problem of USB and LSB reception they were receiving in both DSB. It remained a problem, the FM sensitivity is normal, when moving to any AM or SSB S9 +30 signal before passing the S8 or S9. I am suspicious of D1076, D1078, D1068.
I would love to get your opinion before I venture to replace these diodes SMD.
Thank you!
73 of PY5KC
Alessandro
acscwb@bol.com.br

Anonymous said...

Hi everbody . I would like to thank particularly EA5AGV Jose and AA7FV Darrel and general thank for others OM contibutions.

I've purchased a second hand FT 857D (2007 model), like new because never been powered before me !

Unfortunatly I notice immediatly the crackling noise on my 857D .

I've been convinced in adding the 10 nF smd capacitors , because beeing new this radio shouldn't be bad !

I operate myself my FT857D and with time and its now REPARED !!

It's unbelivable , why didn't Yaesu engeneers put these recommanded capacitor ???!!

At last i've also purchased a TS2000 whithout any problem !o)

73 and Thanks for reading .
F5RAG Iñaki.
Saludos , amitiés .

Hope to Ear you on this air .

Anonymous said...

good day my friend!

i would like to share this about ceramic filters which i found on the net:
http://sv8ym.blogspot.com/2010/07/mysterious-case-of-withering-filters.html

nice website, very informative, keep the good work! i learned a lot from this site! tnx
dw2nah/jonathan
ilocos sur, philippines

Anonymous said...

Hola José
Usted decirme dónde puedo comprar para sustituir los filtros de cerámica en un FT897D que usamos aquí en nuestras actividades con los Scouts?

Anonymous said...

Greetings Jose,

Sad to say, the ceramic filter misuse problem appears in quite a lot of other receiving gear as well. I, too, stared with disbelief when I saw sizable DC voltages being applied to ceramic filters. The result is slow degradation over time, just as you've noted; either the receiver goes deaf, or it develops a case of the crackles. I just replaced three failed ceramic filters in a Realistic STA-90 (ca. 1976) that was deaf to the world -- all three of the filters see 5 vdc or more when the unit is operating.

Thanks for the informative site!

73,
Tom N0GSG

http://n0gsg.no-ip.org

Anonymous said...

These filters are also found in the Vertex Standard series of commercial radios. They are dropping like flies. Especially the VX2200 VHF and the VX354 VHF. The symptom shows up after reprogramming channels to narrow band 12.5 from customers using only wide band. And by then the radios are out of warranty. Talk about mad customers.... And worse, Im scared to put the TOKO filters back in. I'm having a time trying to find replacements by another brand.

A frustrated Vertex Standard dealer...

Anonymous said...

Hola/Hey Jose and folks! Que tal? Tnx for the info. Seems to be that Vertex Standard VX-351, 351PMR and VX-146 have the same problem. 73 de Jukka OH2JIN

Anpu said...

With my FT897D, i can receive on both lsb and usb when other station transmit only in lsb. And even he can hear me on both LSB and USB when i transmit on LSB on 7mhz. What could be the problem. Please help. I tried by transmittig on USB, and the other station can hear me again on both LSB and USB.

Jose EB5AGV said...

Anpu, what happens is that a wide filter, due to leakage, is in the circuit, instead of only the narrower SSB filter. That means that thre is no proper LSB/USB filtering and the result is that the rig works in DSB (double sideband). So you need to replace the three 455kHz IF ceramic filters to fix your unit.

73 JOSE EB5AGV

Anpu said...

Dear jos,
Tnx for your comment. I am still brave to open my ft897 to fix it. but adding cap is advisable? i m from india and worried if i can get those ceramic filters,.... cheers..73s

Anpu said...

Dear jos,
As per your advice, i have replaced cf1005 = alfym455h with a murata equivalant -but not with an exact pin to pin equi- and it solved my problem of DSB! Great job! Now my rig is on road... 73s

Eduardo González said...

I found exactly same problem with ts-2000, ft-897, vx-7, vx-6, vx-8, marine Icom radios, Motorola FRS and others commercial rigs. Just a pandemonium!

Lars Erik Hinrichsen said...

The fault also has arrived at my 3 year old ft857d, and have observed all the problems you describe. My choice in the future is not Yaesu products...

rgds oz1fjb/ou2v

Jose EB5AGV said...

Hello Lars,

Unfortunately even if you don't buy more YAESUs, you could have a similar problem. I have replaced tons of bad filters on other rigs, as Kewnwood TS-2000, TM-D700 series, and so on. It is a mixed fault both from rig manufacturers, who didn't use blocking DC caps but also from the filter manufacturer, who produced badly sealed units.

73 JOSE EB5AGV

Anonymous said...

Hola Jose. se han cambiado los tres filtros y a quedado bien excepto SSB.
Me reciben de igual manera en USB que en LSB, igualmente recibo en LSB que en USB. (double sideband)
Que puedo hacer?

Anonymous said...

The problem seems to be that the filters have had a bad batch that were improperly sealed. To expand on the info that is common on the internet; as usual the whole story isn't t there. During the soldering process, there is a couple of chances that water leaks into the improperly sealed filters - washing and water based flux. It is likely in the majority of the failures, the water was already in there from when the radio was manufactured and was detined to fail. This is why most are replaced without blocking caps without further issue, or radios that lasted without failure. No water, no electromigration. Maybe if no water was already in there, and the radio was exposed to humidity or got wet, etc. - but since the pcb's are flooded during manufacture, this is probably almost never the case.

Pradeep said...

I have FT897D, no out or very less power out put in SSB,AM and CW but in FM mode it works fine, replaced 455khz ceramic filters still the same ,,, any suggestions please send me to vu3edg@gmail.com

George said...

I have repaired a number of FT897's with this issue - so far all the filters I have seen have no sealing at all, and come apart very easily, and are always full of wet green corrision. The replacements sent out by Yaesu are now fully sealed with epoxy resin, that should help prevent any further issues.

George G7GQC