Ts440 uneven am carrier across HF

[KD6VXI]

First,  I do expect some variability from band to band.   That being said....

My TS440 has NO carrier almost on ten meters.   I can,  however,  produce 100 ++ watts pep on ssb,  and almost 150 watts of FM.

I have done the alc adjustment to get decent AM out of her

On 40, I can get 150 watts of carrier.

On 20, she can muster about 25, 15 meters is in the neighborhood of 10 watts.

I've had the radio a long while,  and even in the days of Cb,  it could barely make ten watts of carrier on 11.  I don't think it would be a watt today.

On air reports are great,  drives my amp wonderfully.  

Any of the 440 gurus have an idea or two before I tear into the service manual again?   Bear,  'vw,  Bueller???

Thanks,  in advance.   Was going to try some 15 or 20 am this weekend,  and was like,  wtf....   Haven't used it above 40 since getting it back up.

--Shane
KD6VXI

[flintstone mop]

I have a 440, my first rig, after finally earning a ticket.
Puts out CW power on all bands. AM carrier power seemed to be the same across the entire operating range of the radio.
Do you see a lot of excessive ALC in these lower powered bands? Is there a tuner between your 440 and the amp?? I assume that you're not trying to attempt to operate 25 watts barefoot on the lower bands.
25 watts is more than enough for10M when the band is open.

Fred

[KD6VXI]

I'm out in the shack now.

Yes,  I do run 25 watts at times.   When working local NVIS,  seems to work OK.   I have legal limit for trying to talk to anywhere else.....  Picture is of feeder before rerouting after putting amplifier in line.   25 watts didn't arc that....   :-)

It displays this behavior into the dummy load as well.

I have the auto tuner in the radio,  but only use that when using the amp.   Otherwise I use a kw matchbox for tuner / conversion to balanced line.

I have no alc activity anywhere.   Alc has been adjusted to not cut back am audio.   Radio has no problem going to 200 pct pos peaks on 40 or lower, from 20 Watt carrier, mic jack input.   

--Shane
KD6VXI

[WBear2GCR]

Shane,

Not sure what is the picture you posted??

Anyhow, what your report seems like something I have never seen myself.
You can download the complete service manual. I would. It shows a variety of test procedures to
set up the rig. It might lead you closer to the problem.

Odd that you report 150watts on 40. Afaik the rig should not be able to hit 150watts CW.
This indicates that maybe the problem is in the ALC since you also say you are not seeing ALC indication?

At least this is a place to start.

                      _-_-

[KD6VXI]

The alc has been readjusted to not have any function,  at a flat vswr,  to 200 watts (I had set it at 150, FM / CW on 20, not realizing at the time the radio had a problem across HF with power out).   This gives me the ability for almost 200 watts fm / CW on 40 and below.

The readjustment of the alc is a documented mod,  from. Amfone.net and others,  to prevent alc action on am.   Shouldn't have any bearing on an unequal power out across the bands.

I have the service manual.   I wasn't able,  upon a quick perusal,  to locate any settings amounting to what I'm experiencing,  although I KNOW it exists.

Not wanting to shotgun, so I asked.   I've a feeling I'm not explaining myself correctly.....   Been having a problem with that at work,  too.

--Shane
KD6VXI

[flintstone mop]

I do not want to get critical of your thread but those adjustments for the PA. and ALC and foldback circuits are very sensitive. These aren't diddle controls that are tweeked for the most smoke.

Good luck

[N2DTS]

You risk blowing something up at those powers.

The carrier is generated in the balanced modulator by unbalancing it or something like that, then it gets mixed up to the correct frequency, so maybe a xtal is out to lunch.

The carrier level should not be band dependent at all, but maybe some heterodyne xtal is bad?

[flintstone mop]

You risk blowing something up at those powers.

The carrier is generated in the balanced modulator by unbalancing it or something like that, then it gets mixed up to the correct frequency, so maybe a xtal is out to lunch.

The carrier level should not be band dependent at all, but maybe some heterodyne xtal is bad?

Who knows what else was diddled with in the OPs radio.
My TS440 has been perfect since new. I did some mods on the receive audio circuits for better audio and then the famous TS440 dotsssss across the screen problem. Some strange process used by Kenwood that would trap moisture in some PLL circuits and they would unlock.

Fred

[KD6VXI]

It's sometimes amazing how things get lost in translation,  or how people zero in on one thing,  ignoring the elephant.

This problem has manifested itself since I bought the radio,  say.....   Nearly 20 years ago.   A good 15 plus.

It had a catastrophic negative hundred and ten volt pulse kill the controller boards (vfo / etc.   Two boards sammiched behind the faceplate).   Via the service manual,  I was eventually able to make the radio a great R5000.  Fast forward 5 more years,  learning lots of digital,  etc along the way,  and I was able to.find the switching problem,  and the radio is now completely functional.  

Following the modification info found on this site and the other well known am window,  I brought the alc up so on twenty meters,  I was able to get 150 watts.   This is a documented mod.   I did it on twenty,  because that's what the service manual said to align at.   This was measured with my 500 Watt slug into a B &  W dummy load,  which presents a flat match across the HF spectrum.

To my knowledge,  nothing else has been twisted,  turned or 'diddled'  with.   I cannot verify that,  however,  as I've only owned the radio half its life, I'm the third owner,  and I've lost contact with the friend I purchased it from in CT.

Here is my dilemma:   Power out,  across the hf spectrum,  is uneven.   This is causing over 200 watts to be available at 75 meters,  and under 150 at 10 meters.   This has zero to do with the alc pot being slightly opened up,  it did it before.

Before I started looking at it on the bench,  I thought I'd ask if anyone knew what the problem could be,  could point me to the mixer area that could be causing this problem,  etc.

As I STATED.   I run it at 25 watts of carrier.   My voice causes it to peak at approximately a buck and a quarter.

Appreciate the help.  Picture enclosed to see the actual w2vw mod followed.

--Shane
KD6VXI

[flintstone mop]

OK Shane
I did not know that you are probably third owner.
But why are we trying to get blood out of turnip? 150 watt carrier??? I don't understand why folks try to push solid state devices to their limit. I can imagine what the IMD specs are when that final peaks at those levels.
Older solid state stuff needed a lot of headroom to perform without failure or distortion. Today's magical FETS and whatever are the amazing devices.

Fred

[KD6VXI]

I am not trying to get a hundred and fifty watts of carrier.

Whatever you can get pep,  your u can do with carrier on fm,  or CW.   It's a lot easier to get a meter reading at 100 watts of carrier rather than a voice peak.

I am only asking which transformer(s) are in the TX if.

If worst comes to worst,  I'll scope it after each mixer.

I'm leaning towards the stagger tuning of L19 on the rf board. In the past,  on ten meter stuff,  I've found that the xformer on the output of the mixer,   buffer or driver can cause uneven power output.

If I want to run obscene amounts of power,  I've a 3000, a 5k and a couple other tubes,  a 16 device solid state no tune box,  a Harris legal limit commercial box and an sb220 .  Creating qro is easy.

The only point of the increased power out of the 440 is to keep the alc from acting upon the audio.   I still only use it at 25 watts of carrier,  and drive my amplifiers with it.   Factory you cannot approach anything near 100 pct from the mic jack without the alc distorting the audio peaks.

It's not just the carrier that is uneven,  power output,  pep and CW,  is.   

I know from my yeasu,  as well as other radios I've operated (solid state era) that if I set my carrier at 20 watts on 75,  it should be the same at twenty meters.

That,  my friend,  is the problem.   I just need to get power output even.   Then I can set the alc where it's supposed to be,  and everything will be happy in mudville again.

--Shane
KD6VXI

[N2DTS]

I would think there would be an alignment that needed to be done band per band.
Same as the SDR radios that allow you to adjust the power output on each band, which is done in the PA drive levels.
Maybe frying the logic makes a power alignment needed again.
Maybe it was stored in eprom or something.

My ANAN came with various power outputs on each band, but because its software you can adjust the power out on each band to any value below 15 watts.
It will do 20 watts on some bands, but not all...the band pass filters change things...

[KD6VXI]

That's what I'm wondering,  Brett.   It would appear from   
The block diagram that the only bandpass filtering is after the PA....   Well,  sans the if filters themselves.

Then again,  it could be something with negative feedback.   

Not the guru on this chassis,  though by the time it's all done I might be...   Lol.


Thanks!

--Shane
KD6VXI

[N2DTS]

I had one back when they were new, and an icom 735.
The 440 was a better mobile rig.
I did some minor audio mods but never dug into it past that.

[KA0HCP]

The readjustment of the alc is a documented mod,  from. Amfone.net and others,  to prevent alc action on am.

Say no more! If you found it on the web and AM Forum it must be true!  

1.  I personally believe that ALC serves a legitimate purpose, and am unconvinced that the TS-440 is unusable without ALC disabled.   Did you test and verify that audio was distorted with all settings of ALC before performing the mod?

2. Variable peak out on different bands with ALC disable may not be a surprise.  Again, one function of ALC is to smooth things out and give the rated output on all bands.  When you started disabling and tweaking things out of design, results will be uneven.

3.  What does it matter what the instantaneous peak output is?  You have exceeded design ratings.  There are no specs or performance guarantees with the circuit modified or disabled.

4.  Accurate PEP measurements are heavily dependent on the type of meter.  What are you using? Is it a powered meter known to be accurate?

5.  How are results band to band with Average Power readings?

Good luck, b.

[flintstone mop]

There is a member in this forum who was modifying TS440's for hi-fi AM TX audio. The radio was awesome when he modified a 440 for me that I bought from eBay.
The TS440 I mention owning in earlier replies to this thread was only modified for better AM audio.
The modified 440 came back with a different filter inserted somewhere in the I.F. balanced modulator circuit for the extra audio B/W. There was a separate audio input added for "station' audio.
He warned me that the ALC was disabled to allow for uninhibited pos peaks and to make sure that the radio was always seeing a near perfect RF load, or the finals would be damaged.
The moded radio did not have any problems with a CW carrier or AM carrier on any bands. The modded radio receiver was not as sharp for tuning on SSB as my 'virgin' 440 is. It seemed like it was a wide barn door and sloppy tuning using SSB.
What happened in Shane's radio is a true mystery to me and I will keep tracking this thread. The '440 is still a nice little radio.

[N2DTS]

The problem with many of these type radios is/was that in the AM mode, anything over about 50% modulation triggered the ALC and the carrier would bounce around like a bad controlled carrier rig.
It sounds nasty.
If you are going to make something work on a mode, why not make it work correctly?
(They still do it)
The trick was always to disable the ALC in some way so you could run the radio at 20 watts carrier and get 80 watts (or 100) pep without the carrier jumping around.
I think maybe Yeasu got it right?, and everyone else did not.

In my 440, I used a small reed relay to bypass a filter during TX.
The 440 had a nice noise blanker for mobile work, and some had a built in tuna.
Mobile ssb was easy, AM was still a hash of static when in motion, static buildup...

[flintstone mop]

The word got around with this design of radio of the 80's that there should not be ANY ALC meter action in the AM mode. With the human voice and no quality audio processing inside the radio that was going to be impossible. Plus a typical Ham is just going to try to wing it with improperly matched audio into something that wasn't designed to be hi-fi in the first place.
I was in QSO with a really nice station on 160M, can't remember the call. I think he was in Erie Pa. I'm guessing the Yaesu FT 9000. It was a $9000 200 watt transceiver. It sounded like the greatest SDR AM we hear these days. He said he did not do any mods it just performs. At $9000, he said it BETTER "sound good on the air". That rig was all setup for Hi-fi audio and had it's own EQ and processing for audio built in. Huge audio. I never heard anything like that.
Fred

[N2DTS]

Yes, at $9000.00 it better work quite well!
There was (at one time) a 400 watt radio, that would be 100 watts carrier...

[KD6VXI]

Agreed,  most solid state radios sound horrible when you get in to alc action on am.

The best way I found,  on the 440, was an external limiter,  or use the processor built in,  dial enough mic gain to keep alc off,  no more.   Was so high pitched,  but clean.   Should have been,  did about 40 to 50 pct mod.

My FT857 makes about 60 pct before pulling back.   The fix on this radio,  and others,  was easy.   Inject a small amount of voltage into the alc jack,  to the point the carrier began to be reduced.   Beautiful am.  Ran that way legal limit mobile when I drove truck.

I've always liked the icom radios,  out of the box.   At least the ones I've heard eard did sound OK.   Nothing sdr or broadcast, but.....

Haven't been in the shop,  work calls.   

Wish that Santa guy would bring me a 9k dollar radio.   Or a 90 dollar radio!

--Shane
KD6VXI

[KA2QFX]

Being very familiar with, and a fan of, the TS-440 I naturally read your post.  Having read all the comments about ALC and power levels “obtained” I cringed.   Fred, MOP, was most succint in his caution, I'm less so.  Although I'm reluctant to post this repsonse I am compelled to do so by my academic influence to share what I've learned over the years.
ALC, like BALUNs, are one of those subjects that seem to evoke emotional responses filled with conclusions from mis-ascribed phenomena.  The following broadly addresses the matter of ALC for other readers as well. That being said...  here goes.

The following are some excerpts from an article I wrote some time ago. I've edited it quite a bit to address your specific radio and question, which I address at the end.

To begin, I simply must advise you to NOT reduce your ALC controls.  This radio should under no circumstances be permitted to produce more than 110 watts.  Here's my reasoning, and more.

Fear and Loathing of ALC: Dispelling the myths of ALC detriments.
 
No one likes the idea of being subject to involuntary limitations.  But no one would argue that seat belts or “rev” limiters or even circuit breakers don't have their place.  So too is ALC in modern radio design a useful necessity.  Average reading metering and modulation asymmetry contribute greatly to the preception that the ALC is inflicting WAY more restriction than is acceptable by many operators.  Upon careful scrutiny however with both time and frequency domain analysis this is found not to be the case.

Early ALC systems, ala TS-520, TS830,... used limitation at the audio stages alone, before the balanced modulator. Effectively, these functioned as crude audio compressors depending on their filter characteristics in developing control voltages.  Later, ALC systems that operated at the RF level, farther down the transmitter chain, were utilized to protect the less tolerant solid state finals then becoming popular. These also permitted a quick acting drive limitation for SWR protection, which certainly was a welcome function.

RF versus Audio Distortion:
Under normal circumstances the actual audio distortion produced by ALC limiting is minimal.  When the gain of the transmitter chain is reduced by ALC the SSB envelope of the RF is distorted to a small degree. This is not unlike the distortion of a audio limiting processors in the audio chain except it's occurring after a balanced modulator.   Until about -10dB of reduction, this distortion is almost inaudible for amateur purposes.  

The audible problem does arise, particularly in AM, because the ALC is not reducing the audio driven into the balanced modulator, rather well after it,  So in driving the ALC into high levels the balanced modulator is being driven past the point where there is sufficient carrier level to be AM modulated by the audio.  Being a balanced modulator, it readily unbalances the bridge and gates through whatever RF is required... as a sideband! The result is a SB component produced in the negative modulation peaks where the resultant RF output of the modulator has reversed in phase, and produced an envelope where none should exist. This is commonly referred to as “Going into sideband”.  Sounds awful!

In plate modulated AM this would be negative clipping. Unlike such clipping, such sideband generation does not produce RF “splatter”.   So the problem is not the ALC, it's too much audio.     If you set the ALC higher you can set the carrier higher and have a little more room for negative peaks.  This is not an ALC limitation, it's a balanced modulator problem.  But in lieu of plate (or collector/drain) modulation, we're stuck with this balanced modulator limitation.  BTW: The FT-101s actually do have a nice collector modulated stage for AM.

A 100 watt ALC limit will allow a 25 watt carrier with 100% modulation.  A 20 watt carrier will allow 100% modulation to only 80 watts peak before the negative modulation peaks are distorted.  A 30 watt carrier would allow more negative peaks but the positive peaks would limit the overall modulation to about 90% of potential before ALC engages.  So there is really only one setting for your carrier, 25% of your ALC limit.  

RF distortion, which is unheard by most, is a product of driving these radios beyond their rated limits.  Solid state finals generally have higher orders of non-linear distortion to begin with. Some manufacturers have offered Class A operating modes to ameliorate that. But operating Class AB, as this radio does, does not permit much leeway in driving the finals of these radios beyond their design spec before second and third order products start rising quickly.  Yes, they can handle the wattage, but you're not doing your neighbors any favors and your certainly not gaining enough 'dB' to matter.  

If you want to resolve both issues of audio distortion and ALC limitation, use outboard audio processing to increase your audio density before the balanced modulator and still keep the peak to peak levels within the operating parameters of the radio.  

ALC specifics of the 440:  Not all ALC circuits are the same. In fact, recently, many manufacturers have started using the ALC level control circuitry as part of a closed loop carrier control stabilization.  This introduces all sorts of issues on AM which I'll describe briefly later. In the 440, the RF Carrier level is set solely by the gating of carrier RF to the balanced modulator using a potentiometer setting. Hence, the famous “carrier drift” noticed in these radios. Since the gating is done through a diode, operating near cutoff, it's very temperature sensitive and the carrier rises as the radio warms up.  In my estimation this is a far better problem than the “stable” radios using closed loop feedback.

In the closed loop situation, the RF level is rectified to produce a DC control voltage. That's fine for FM but on AM you need to modulate to twice that level to achieve 100% modulation.  How is this possible?  Low pass (audio frequency) filters are employed in the ALC loop.  As long as your modulating frequencies are high, ~ 1KHz very little carrier reduction is seen during modulation. But since the ALC does need to respond, eventually, a compromise between response time and permissible modulating frequency much be reached. Hence, trying to get low end audio on AM through these “stable” radios is near impossible without severe ALC interaction.  I'll take the carrier drift of the TS440 thank you and touch up the pot now and then.

I also use ALC as a tune up aid for my amplifier in the station.  I run a grid driven tetrode which is sensitive to overdrive. Using carefully metered grid current to develop an ALC signal sent back to my exciter I can be assured of keeping my drive below damaging levels for all but milliseconds.  It's saved a LOT of tubes from my clumsy oversights.  So, don't be so quick to malign your ALC.  You certainly will be tempting fate by crippling the ALC.

VARYING DRIVE ACROSS BANDS:
To address the specifics of varying  drive across the bands one must consider what stages of the radio are sensitive to band change.  In this radio, there is very little circuitry which handles significantly different frequency with band change.  For this radio it begins at T25 the output of VCO1 on the RF board. If this were the problem you would likely hear a reduction on receive as well.
After that, specifically addressing the transmit chain, we move to L18 and L17 on the RF board and proceeds through the transmit mixer and on to the PA.  Most all of this is broadband circuitry with the exception of the filter board which switches low pass networks in to the output for final clean-up.  Both SWR and ALC detection occur on the filter board as well.  

Assuming you are NOT seeing dramatically rising ALC or SWR indications, which are limiting the output, it stands to reason that there is in fact a stage which has very reduced gain or attenuation on the higher bands.  Using a scope, or similar RF detecting device, it needs to be determined which stage suddenly has less output level given the same input level as you change bands.

No need to get real technical here. You're looking for a gross discrepancy between in and out from band to band. Starting at the output of VCO1 and moving toward the output (L18, L17...) I'd just toggle from low to high band until you find the spot where it drops on the higher band.  
  
Best of luck.  Let us know what you find.

Mark
KA2QFX

[flintstone mop]

Very nicely put together Mark

Fred

[KD6VXI]

Mark,

I agree wholeheartedly.   It's NOT my want to see the ls I do.   When I can't see a couple watts on ten meters and see a couple hundred on 160, this is bad.   

The service  manual available on the Internet doesn't cover the circuit to the extent you did,  but the Last couple days I've been reading it after ten and twelve hour days:  And came to the general consensus you stated....   But it sure is nice to have a hand.

Thanks,  I do appreciate it.   I was informed today it's long days until Xmas,  so I may not have time to bench the radio until then,  but I will report back.

I have built a dual op amp negative peak limiter based on QIX pdm input.   Even without it,  I easily hit 125 pct peaks.   

Once I have the power problem solved,  I'll be a happy camper.   Then the alc will be set to reason:

I just reread one of my statements made above.   I did NOT readjust the radio to have no alc action.  Autocorrect on the phone........

Mark,  thanks again.

--Shane
KD6VXI

[KA2QFX]

I know you did not eliminate the ALC, just reduced it.  After the holidays hopefully we can all settle down and heat up a soldering iron and some coffee. I'll eagerly await your findings.
73 and Happy Holidays.

Mark

MOP: Still burning up verticals? Nice to hear from you. I haven't been around in a while. The boys are keeping me very busy these days. But I am building a new antenna to replace the one that got trashed a year ago, just waiting for a blizzard to start erecting it.

[flintstone mop]

MOP: Still burning up verticals? Nice to hear from you. I haven't been around in a while. The boys are keeping me very busy these days. But I am building a new antenna to replace the one that got trashed a year ago, just waiting for a blizzard to start erecting it.
[/quote]

Good one!!! I had a victory over that POS vertical by installing a vac variable at the point where 80M began. What a circus that was

Fred