The AM Forum

Until I can get my stable of BA AM equipment running, I have been wanting to get on AM and start an AM net up here in Southcentral Alaska (Anchorage and surrounding areas). 

I have a Kenwood TS-440S with only a YK-88C 500Hz filter.  There is a slot for a SSB filter.  Is that where I would put the YK-88A filter if I wanted it for AM?  I did not see any reference to the AM filter in the operating manual or the service manual.  Would it help me on AM on the TS-440S?  And finally, how much power can I safely run?  25 watts is what I read in the op manual.

I just hate to buy a filter until I know where to stick it and if it will help.  Or, is this a poor use of resources?   Will it work?

Any advice would be appreciated.  I haven't been on AM since 1965 and 1966. Just 90%CW and some SSB.  See 1966 shack photo at http://www.al7fs.us/

Thank you.

73, Jim, AL7FS

Jim,
     I've used my TS-440 quite a few times on 75 meter AM and usually people give it ok audio reports. I don't have an AM filter for it, but the rig seems to receive OK. I use a TS-570 sometimes as well and run it through a SB-201 linear. For the 440 I try not to run more than the prescribed 25 watts of carrier. I'd say, just give the 440 a try. There are some mods I've seen for the 440 on AM but I've just used mine stock. Good luck.
     ---Marty, KK4RF, Suffolk, VA---

It should still TX thru the stock 455 KHz ceramic SSB filter, the optional one is for the 8.8 IF.

Carl

I understand the TX would be standard.  It is the RX I am interested in.  None of the documentation mentions the YK-88A filter.  Where do I plug it in is the question.  Surely the YK-88A is for RX.

I appreciate the responses.  Eventually I will get this figured out.

73, Jim, AL7FS
Anchorage, AK

You don't plug it in. It gets soldered in. The larger Kenmore rigs use the plug in boards. Filters are the same thing except for the PN suffix with a board.

After installation there's a jumper to connect to diode switch the filter into operation.

I have one and didn't think it was worth installing. AM receive still goes through the little cube filter @455kcs.

If you do any mods at all start by increasing c-135 on the I.F. board by 10dB. You will have the board up ended anyway. It can be flipped with almost all the harness plugged in.

The 440 can be mistaken for a "real" AM rig with the correct work.

Get it all here!

http://amwindow.org/tech/htm/ts440/ts440mods.htm

<Just saw the new post...QRX...Hmmmm...I am going to have to read that several times.  I had actually found this write-up but I did not grasp the material properly.  I think I am figuring out that the YK-88A is a waste of time although I don't know just what to do yet.  Read...read...read...>  I wonder why so many people buy the YK-88A?  What do they use it for?

Original post as follows <unchanged although I have the new material to chew on>:

Okay on soldering, that's not a problem.  I am supposed to solder in the YK-88A into the SSB filter slot?   Is that right?  My original question read, "There is a slot for a SSB filter.  Is that where I would put the YK-88A filter?"  

Are you saying that one does not install a YK-88A filter because it does one no good?  I understand it does no good on transmit.

I am not clear on increasing c-135 on the I.F. board by 10dB.  Was dB what you meant?

I apologize for being so dense.  I have the rig opened up.  I have the soldering tools and a Hakko 808 if I need it.  

Everyone must be getting this info from somewhere.  I thought I read through the manual and service manual.  Seems I need to go back and read it again although I know there is no reference to the AM filter.  I have done searches on several email lists and with Google to no avail on this topic...which surprised me.  Not even the Kenwood TS-440S Yahoo list had any info.

With ongoing appreciation for the help...

73, Jim, AL7FS
http://www.AL7FS.us

I would not install the YK-88 AM filter.

What I have done is use the rig without an AM xtal filter - the position is bypassed entirely in AM anyhow, but have changed the 455 ceramic filter for another Murata ceramic filter with far better skirts and iirc the one I liked best
has +-9kHz. (-6db iirc) bandpass.

It is a drop in replacement for the stock filter, even though it is physically 2x the dimension in length - Kenwood has the holes in the board already there! Apparently they either intended to use another filter or else were nice about it for people who wanted to drop in another.

The result is imho quite wonderful receive audio. As already noted the xmit still goes through the "SSB" bandwidth... (although I am not sure thinking about it now, if I pulled the stock SSB xtal filter if that would widen it up or not... hmmmm...) but anyhow there is a nice mod from Mark KA2QFX for the xmit audio and notes from Dave W2VW. I also did some experimentation on the audio stage and that can be found on my website with a google search, although I would stick with Mark's xmit advice and the Murata filter swap at this point in time.

Which Murata filter?

I don't have the number handy - I am some distance from the shack these days... but you could figure it out as I did by browsing the Murata site and picking the one that is black, fits in the larger hole pattern, corresponds to the stock hole pattern in part and is +/- 9kHz wide... or maybe Mark will show up and look at the ones I sent him and post the number? :D

                      _-_-bear

Great advice flowing here.  I will not buy the YK-88A filter.  I will hang on for more Murata info as I would like to improve the RX audio.  And I will go look for the article/mod from KA2QFX as well as digesting all the other articles I have found or been pointed to.  I printed out the W2VX document and also the referenced Rich Measures, AG6K, article.

I am not nervous about getting into the rig and unsoldering and soldering and such.  However, I usually need to know what I am trying to do in detail before I do it.  I am not a good technician although I have built many kits including my K2.

So much to learn...so much more to discover.

73, Jim, AL7FS
http://www.AL7FS.us/

If you don't already have the Kenmore filter the money will go much further elsewhere.

Do not bother retrofitting a filter into the 455 khz I.F. unless it has a decent shape factor.


Bear, I've asked you several times exactly what filter it is you suggest using. Is it a govt. secret?

I'm really interested since I spent numerous hours checking mine in the circuit. It would be nice to find out what I'm missing. Thanks.

http://search.murata.co.jp/Ceramy/CatsearchAction.do;jsessionid=6C4AE5FE2B4BD11B7877C03FA0D04CC0

Check how many results / page you want.

You can get all the way up to 15Kc passband on 455Kc plug / solder in filters.

ALSO, if you can find one (flea market, etc), most CB Murata 455Kc filters are a bit wider than the Kenwood ones :)  CHEAP way to get a bit better passband, find a dead unit at a flea market, etc., and you're good to go.  I've used them in a couple conversions, with dead CB gimme units.

Otherwise, using the search engine above, custom tailor the IF passband you want (at 455), and you're all set.

Also, Murata makes many OTHER filters that may or may not pique your interest.

--Shane
KD6VXI

And KIWA has some nice AM filters also, Ive been using them in boatanchors for years to improve skirt selectivity.

http://www.kiwa.com/kiwa455.html

Where the hell you been hiding Shane?

Wow, I think I may be in over my head.  I read both the referenced articles as posted by K4HX and at a high level I think I got it but at a technician level...not so good.  All I can do is keep reading and learning for now.  It might be easier for me to get my B&W 5100A, Johnson Ranger I, Hammarlund HQ-180 and HQ-170, and the National NC-300 going. 

I am not giving up on this as it is fun and interesting.  Please don't kill the thread too soon.  :-)

This OOTCer has lots to learn.

73, Jim Larsen, AL7FS
http://www.AL7FS.us/

Simplification:

Don't spend any time or money installing a filter unless it has superior shape factor to what's already there.

Most of the TS-440 blurbs on the internet are no longer the best or even cheapest way out for receive. That includes mine. Plumbing to a cheaprock at the first I.F. would be the best way.

Transmit is another matter.

Thank you for the advice. I think I have come around to the point of backing off on this project.  Using the TS-440S for my ARES go-kit might just make more sense. 

73, Jim, AL7FS

Dave,

It's not a secret at all... I am no where near my shack these days, and they are on a shelf... the replacement has decent shape factor and sounds fabulous imho, it works just right to listen nicely to a signal on 3880 and not get clobbered by guys up or down from there... to me it sounds great.

Maybe QFX will read this - I sent him two to try (don't think he has done it yet) some time ago, but maybe he has them in arms reach and can read off the numbers and post them up.

I was intending to be in the shack this weekend, but we got snow big time dumped on us up here, and I did not make it. Maybe monday, and then I have to remember this, when there is so much other stuff whirling around now... :(

The one I picked had the right pinout to fit the Kenwoof footprint, and has the longer case, with the better shape factor than the stock, and it was +/- 4.5kHz spec, which iirc is 6dB down?? Could have been the just wider one, +/- 6.0kHz @ 6dB down. Dunno, I got a range and tried them all, this one sounded great and worked fine, did not let too much "creep" in from the side and was not too restricted. You can probably figure it out from the Murata website as that's all I did to arrive at the unit.

If I can REMEMBER to look on Monday, I'll post it. Yeah, right that's simple...
all I have to do is to REMEMBER... uh, what was that we were talking about??

                        _-_-bear

Probably it was from here:

http://www.murata.com/products/catalog/pdf/p05e.pdf

From the CFLWA group... although I may have picked  from the CFLWB group or the CFLWA-Y group. I recall spending some time looking at the curves supplied and deciding. Any of these perform much better than the stock unit that is in there. Way way better.

I was considering making up a board with a buffer or gain stage and cascading two, but I thought, "try it first" and I did, and decided it was darn good. Left it at that.

                   _-_-bear

                           

I have to chuckle at myself.  I am technically intimidated enough to be afraid to comment.  I got lost several messages ago.  That's not a bad thing as each time I read this stuff I retain a bit more.

Thank you for your help.

73, Jim, AL7FS

I think the 440 is similar to the 430? I am extremely pleased with the optional 6KC AM filter in my TS430-S. Before that, it used the stock SSB filter and that was too narrow for SWL and for amateur AM. I also installed the narrow CW filter and the FM unit when I installed the AM filter. There is still a deficiency compared to receivers that have several selectivity positions (sx-28, R390A..) but the addition was well worth it.

Jim,

On the IF board of the 440S there is a small black plastic 3/8" square (on the top) and 1/2" high box. That is the 455 kc IF filter - not counting the "fancy Dan" filters you can put in. The kicker is that everything goes FIRST through that little black filter, then to the optional filters.

This works because the optional filters are all tighter than it. However it is very broad in terms of its skirts. Skirts being the slope of the attenuation OUT of the number of kHz that you want to keep (listen to). (To be complete, it is also the depth of the skirt, or in other words how much maximum attenuation out of the passband it gives - in dB down) In other words, it's a crap filter. Plus it is really too tight in the passband to receive AM so that it will it sound nice, even so the wide skirts let all sorts of garbage in from the sides. (can sound like "splatter")

[In the stock configuration this ceramic filter is intended to make the skirts of the SSB and CW filter "better" by attenuating stuff way way out to the sides a bit more - which is what it does, and by so doing improves the IM specs for the IF section (by just getting rid of  (attenuating) signals off to the sides).]

The solution for listening to AM on the 440s is a nominally wider 1st 455kc IF filter with much steeper skirts, so that you can hear what you want (it is wide enough), but so that the unwanted stuff off to the side goes away.

The filter I mentioned is a "drop in" replacement for the stock filter. Which makes it very nice.

You desolder the old one, solder the new one in, done. Works like a champ! :D

              _-_-bear

The 440 is not all that similar to a 430. 440 has an extra I.F. And does a lot with it.

IIRC there aren't any 455KC filters in a 430 because there's no 455 IF.
The selectivity happens at the 8.3XX meg filters.

weeks later I finally get to the box that has the filters. I write it down. Some time after that I find the paper with the number on it. Then shortly after that - now - I get to post it.

The filter I preferred (of the ones I had to try) was this one:

Murata CFWLA455KFFA-B0  

which is a +/-6.0khz filter.

In practice it is possible with this filter to hear a QSO on 3880 and tune just south of 3880 by a hair and not hear a QSO on 3885 (for example). And the fidelity is quite nice imo.

                    _-_-WBear2GCR

PS. if anyone tries it I'd love to hear your impressions, good or bad...

So all I have to do is buy the Murata CFWLA455KFFA-B0 filter, use my Hakko 808 and lift out the little black filter on the rig and drop this one in.  And then Shazam...it works better?  I could do that.

Jim

Yes.

You have to put in in the right direction and the right place of course.

It's on the top board when you open the top of the rig (iirc) and it is the square top black thingie in the upper right quadrant (if you imagine that you drew a + through the board) and toward the center a bit. There are holes already there for the longer "new" filter. So I suspect that the Kenwood designers either intended to use the "better" filter or just left the provision in case the cheaper one became hard to source... but for whatever reason the holes are there! :D

                      _-_-bear

This is a receive ONLY mod...

That 455 KC filter is used on both xmit and receive.

Hmmm... interesting Dave... 

I got no change in signal fidelity received reported when I did the mod... now I am confusered totally. Ok... fog lifts, the nominal bandwidth is the same then, just my skirts got way better. That must be it.

              _-_-bear

If you are only using the rig for transmit on AM and not rx you can just yank the ceramic filter and put in a wire and do all your bandwidth limiting in the audio like any other AM rig.

Yes, the filter can be bypassed with use of another receiver but there are better ways...
One is to duplicate the diode switched filters with an additional set of components and a 1K resistor in place of the filter. The internal AMT (am transmit) logic bus gets removed from itsk present location and hooked tot he switching diodes of the new section.layout will be critical here to minimise filter blowby.

Well this still is not making much sense... unless there is a LP in the speech amp section (is there??) at least on my 440 the xmit audio did not appear to be any 6kc wide... I was under the (false?) impression that the 440 tries to run the xmit audio through the default Xtal filter - IF it is present? In my rig it is present. So maybe without the default filter (I have another secondary SSB filter in it too...) one gets full width??

I know QFX came up with a way to add a few components so one gets wide xmit audio in AM only. I don't recall if it switched the filter back in for receive. But that would be ideal, I guess.

This replacement ceramic filter does a bang up job on receive, I'd hate to give it up.

                           _-_-bear

There was a time when the design assumption in engineering plastic SSB transceivers was that everyone would be using a hand mic and would want space shuttle audio (I guess now that the Space Shuttle is no more we have to call it something else, maybe subway PA audio) so the mic preamps built into the rigs often had passive compoenents that would roll off the lows and highs in the audio.   So it helps a lot if you work out a way to feed the balanced modulator (which is unbalanced for AM of course) directly with a cap in series.  You have to find the right pin on the bal. mod. chip and tack a cap lead on it and connect the other end to a coaxial audio cable to a RCA jack on the back panel with the shield grounded to the PC board ground (and/or the cabinet--I can't remember which way solves the pin 1 problem).  the cap can be something like .01 uF poly 25 v. for s.s. rigs.  you may have to do some experimenting.  It helps to have the service manual for the rig.   The caveat is that if you go this route you have to be set up to monitor what the rig is doing, i.e. you have to hear the tx audio off air, see it with something like a SB610 and/or scope, limit the peaks, and roll off the high end sharply at 4.5 or 5 kc by about 40 dB, and watch the ALC, because the rig isn't going to do anything for you but take everything you give it and send it out.   Its response should be very flat though and in my opinion, controlling response at baseband is better anyway.

Probably time to study the block diagram.

Several people have good mods for this rig. Some on this board were running them and sounding good almost 25 years ago.

The 8.83 crystal mhz I.F. filters do nothing on transmit in this radio. They are used on transmit in other Kenwood models.

If one takes the time to sweep the speech stages one will figure out exactly what parts need to be changed. Hint: SPICE GIGO. Estimates and numbers pulled out of outer space don't tell us anything.

I'll be writing a white paper someday.

 " space shuttle audio "

Burger king audio??

dave, thanks for the kick... not necessary is it?

the SPICE simulation I did many years ago used the original parts values, and was intended as an exercise and experiment, not as some sort of definitive work fwiw.

I don't mind being 'wrong' - or being corrected, it's an opportunity to learn something.

                      _-_-bear             

Call me when you have some real time, energy and expense developing mods for these.

Ok, I am totally confused. No idea what ur thinking. Please PM or email me if you've got something to say that is personal and/or does not add to the understanding of the topic in the thread.

Let me add, I don't claim any special expertise in ham radio. Not offering a commercial kit or modification. I'm just another ham. Talking about ideas. Sometimes I get it right, sometimes I don't. Plenty of folks on here know a whole lot more than I do. Perhaps you have a superior understanding, if you don't share it and are unwilling to explain or be specific, then what's the point?

If this isn't going to be fun or enjoyable, then what's the point anyhow?

So how about it Dave?

         
                              _-_-bear

I had cause to take a look at the webpage I had put up 5-6 years ago on this filter. That page was more or less a "blog" of what I was doing with it at the time... Seems like I preferred and am running the nominal +/-4.5 filter over the +/-6.0 filter. That's what's in the rig today. With the skirts being better than the stock and not as good as a high quality mechanical filter or similar, it does sound wide enough to me.  Fyi, and fwiw, etc.

                          _-_-bear