The AM Forum

The Green SR rectifier died on the champ. Lucky for me, it was on the bench being worked on when this happend.  It was a Two contact unit.  I ripped it out and put a 1000V  1amp diode in its place.  Fast recovery.. Thats all I had on hand.

The Champ now keys again but every once in a while, The Relays Chatter before latching on now..   

1. Should I try a different type of diode?

2.  Should I change the single electrolytics value?  Its a new low voltage unit.

Attached is the schematic.   Its SR4  above the 5U4 on the Schematic.  The Cap, C65 is a new 47UF 25 volt unit. The old one was a 50MF 25 volt paper.  Resistor is a 47k ohms half watt.  Its on the 6.3 Fil line. 

Thanks in advance.

Clark

Hi


Looking at Globe 300 schematic,maybe it's not Relay 2 that is chattering ,because it's a DC relay(use Dc voltage/current to make it work/DC coil),and a DC relays has only two states on or of.(in this case using half wave rectified 6.3 V ac to activate  this relay))

But this relay (RL2)  activated/act as a AC switch  for  Relay3 (bigger relay)that is AC activated relay in this case 110VAC(AC coil) .I think maybe this Relay (RL3)that's chattering, It sometimes happen.when using AC relays.
Sometimes because the AC voltage is lower than 110 v,or some defect/some dirt in this relay.


Gito

A DC relay will do that if there is sufficient ripple on the voltage. Also remember that a DC relay is an AC relay with a twist.

Ive also had several 24VDC relays used on the tower for antenna stack switching fail yet now work just fine on AC. Must have been the RF affecting the magnetism.

Carl
KM1H

Clark,

If the old rectifier was a selenium unit then you have a little less forward voltage drop with the silicon replacement.  You may have enough voltage that the relay is closing too forcefully and the contacts are bouncing.  Check you voltage across the relay coil and add a series resistor as necessary to put it into spec.  If the voltage level is too high you could also burn out the relay coil during an old buzzard style transmission.

Rodger WQ9E

Hi

Carl wrote that if there's enough ripple in the DC power supply than the Relay will chatter it,s true.
but I think not in this case,because Clark is restoring His globe like the "original" circuit ,and I  think the Globe is design so that the Relay won't Chatter  with this circuit.

And if it is caused by the ripple in the DC power supply than the chattering of this relay never stops as long as it's on ,unlles the Relay is defect or not the original Relay.
Speaking of DC relay used in AC circuit,yes of course it can be done if the AC voltage has the right Voltage,I think the AC voltage needed has a "critical" point.that is, if We used it with a lower voltage than needed it will chatter.To much voltage it may burn the Relay's coil.
So my conclusion AC relay is more prone to Chattering if the voltage is lower than it needs.
And I think if A DC relay has not enough DC voltage it won.t work.


Gito

Thanks for the replies.  I dont know which relay is chattering.  I did not get that far.. All I know is that I used it in PTT for 2 years. No issue.   Then the SR just up and failed.  I put a 1 amp diode across and now it chatters some times.

I think it might be the bounce.. It sure CLACKS loud now.  Before it was a nice click.   When I get back from my Holliday Trip, I will check the voltage across the relay.  If its to high, No problem.  I have boxes of resistors.

So in short...  this was a ONE part swap.. SR to diode.  Nothing else changed. 

Thanks for taking the time to help me.. I will let you all know what I find.

Clark

 I hope everyone had a Great holliday.  Me and Toby the dog made a Car Trip to Nevada so I could be with my family.  Had a great time talking with my 92 year old Grandpa about radio.

I am home now and got a chance to take some Volt meter readings of the champ.

6.43 volts AC on the Filiment supply.
8.30 volts DC after the diode, cap and resistor to the relay.
7.49 volts DC under load keyed.  Still Chattering once every other key down.

So it looks like Rodger might be correct on this one!   Can you suggest a course of action?

The cap is 47 UF, The Resistor to ground is 47K ohms.   The diode is 1kv at 1 amp Fast recovery.

I dont see much if any ripple.  When switched to AC on the relay line, my Digital Fluke rolls around the last few digits. So the ripple is 1MV or less.  Its a steady and solid 8.30 on the DC side.

THanks alot guys!  I hope to get this going today!

Sorry for the ignorance. I am still learning.
Clark

Clark,

As a quick test whether the extra voltage is the culprit I would use a couple of additional rectifier diodes in series to further drop the voltage.  Silicon rectifiers drop about .7 volts per unit regardless of current draw so a pair would reduce this by 1.4 volts.   Add the new diodes in series with the one you replaced observing the same orientation.

 

Rodger WQ9E

Tried that. The FR107 diodes I have are labeled LOW VOLTAGE DROP on the package. I tested this and found .12 volts per diode. I would need a hell of alot of them.

I just sat down and dead bugged a FULL wave rectifier with 4 diodes and a cap.  I clip leaded it off the fill line and tested it. This got me zero ripple and 7.6 volts DC.  So the ARRL book seems correct about half wave being +.45 and Full wave being .9.  Still.. Its to high.  I put a 10 meg resistor on the input side. That further lowered it. But its still 7.3 volts or so.  I guess all that work got me a volt.  I just dont have a 50Meg Resistor and that seems to be about what I need to Drop it down. 

What alot of work for a failed SR.   I guess I am learning though! The relays are labeled 6.0 volts DC.   

Any other ideas?

C

Clark,

What is the DC resistance of the relay coil?  You could measure this with an ohm meter; if you do this remove the connection to one side of the coil just to make sure you are not measuring anything in parallel with the coil. 

Otherwise, remove whatever additional resistors you added and measure the current flow through the relay coil.  Either of these will provide the information you need to choose the correct series dropping resistor.

The needed resistor is only going to be a few ohms and if this is around an 18 ohm coil (my guess) then the needed series resistance is going to be 4 to 5 ohms.

Rodger WQ9E

I will try that.. I measured it at 1.8 ohms but the coil is hooked up. I will have to unsolder it. 

I have tried a Full wave.. I made one and clip leaded it in. Still chatters.

I removed the D104.  Clip leaded it straight. Still chatters.

Replaced the chattering relay with a new one. Still chatters.

Put in old style top hat diode with more volt Drop. Still chatters.

Tried two diodes. Still chatters.

Changed cap to 100 UF. Now 0 Ripple.   Still chatters.

Really odd.  I guess I am missing something here.  I will do Ohms law with the Current of the Relay coil and try a resistor.  Thanks for the help man

Clark

Voltage Drop resistor did not fix it. Still chatters with lower volts. 

Cleaned and adjusted the intermediat PTT relay.  This provides 120 volts to the plate relay.  No dice. Still chatters.  I am out of ideas on this one.

C

Clark,

Can you visually verify which relay is chattering?  This will expedite narrowing down the problem. 

I had managed to forget what a poor job WRL did on some of their schematics and parts lists; it doesn't make the job of troubleshooting as pleasant as it could be.

Larger relays with the spring loaded contacts will often chatter and bounce if they cannot move freely at the pivot point so check that they are clean and operating freely.  Also check/clean the contacts.

The may be one of the truly rare coincidences where the replaced part and the immediate new symptom are not related but it will be surprising.  So check the contacts on RL-3 to see if they are part of the problem.

Good luck!
Rodger WQ9E

The realy is the one handling the plate.  I replaced it last year with a PB plastic covered unit.  Plug in.  Worked great until now. Lucky for me, I soldered and mounted the new socket. I replaced it with a brand new PB unit. Same chatter.

I have since cleaned and adjusted the 6 volt to 120 volt relay.  They ran it this way so you would have low voltage DC on the mic.  That relay is 100%.  We are all at a loss as to why this chatters with PTT but it does NOT if you throw the transmit switch.  I measured AC and DC on the relay.  Its a clearn 7.4 volts at the relay.  Solid 122 volts on the plate relay.

I guess I will put a valiant inline until I figure this out.  It really has all of us Stumped.

Clark

Clark,

The only difference between throwing the switch and using PTT is that relay OR the microphone PTT switch.  Try another microphone to rule that out and if isn't at fault then the root cause of the chatter is the 6 volt relay. 

Are you measuring 7.4 at the relay with PTT closed or is this open circuit?  If it is 7.4 with the PTT engaged then that is 25% over and too much.  If the voltage is close to 6 volts closed then the problem will be found in the contact controlling the plate relay.

Rodger WQ9E

I bypassed the mic jack.  I put a clip lead on the wire on the back of the plug, then Grounded it. This rules out the mic. 

That is 7.4 volts under load.  Do you really think that is to much for a 6 volt relay? 

I put a 10 ohm inline on the DC side.  That did nothing. 

C

Clark,

Although 1.4 volts high doesn't sound like much that is about 25% higher than rated and it may be aggravating a spring that has weakened with age in the relay-thus it doesn't take as much force to close the relay as it did 50 years ago.

Since you have a 10 ohm resistor in series, carefully measure the voltage drop across this resistor and that will tell you how much current the relay coil draws.  Then you can calculate the needed resistor to drop the loaded voltage down to desired.  That is obviously a pretty sensitive relay in the Champ with a fairly high resistance coil.

Rodger WQ9E

Maybe the relay is fine, but the problem is with the PTT switch??

Jim
WD5JKO

I dont know what you mean by PTT switch.    There is a Transmit switch on the panel. This works fine. No relay chatter. 

The PTT switch is in the D104.  I bypassed that and clip leaded the line to ground.  Got the chatter.

C

Clark, did you have the chatter before the Selenium Rectifier opened?

No. Ran it two years.. D104 on lap.  Keyin away..   Took it down to stabilize the VFO.   PTT stopped working in one shot..  Replaced SR with Diode.  Now chatter.

C

Bear with me here..LOL

According to the text books :"For example, if you half wave rectified 120v AC RMS, you would get 85vDC, and if you full wave rectified it you would get 170vDC"

Then why do I get:

6.43 input AC
Output 8.3 volts DC

With a HALF wave rectifier?

According to the text books.. my DC output should be LESS then the AC input.. THis must be my Champs problem.

C

Link to above text

http://wiki.4hv.org/index.php/Diode


Sorry..  I am trying to learn and you guys are really helping  me.

C

HI

Clark have You tried to switch in/test the RL2 alone ,independent than the others relay?Does it chatter ,I don't think so
Looking at the schematic RL2 is the one which "Supply" all the AC relay in this circuit.

Can it be the Switch 1(ON/OFF switch) is "damaged" so there's a "little" resistance or the component around it(RFC7,8).
Logically AC relays chatter when the AC voltage is under the needed voltage.

When the PTT switch  is on, RL 2 is on activating all the AC relays that activated all  the B+ of this transmitter ,meaning there's a 300 maybe 400 watt is loaded to the AC line via Switch 1 ,can it be the ac voltage drops after SW 1.
That makes the AC relays chatter,because the AC input is not high enough

Another option  the AC relay is RL1,RL3 and RL4 ,it can be one of this relay that's chattering.


Gito

SR4 is tied to the 6.3 Volt winding on the transformer.  Are you sure of your work when you put the diode in place of the Selenium?  Go back and double check the polarity of the diode and cap.  You are correct, if you put in 6.3 volts you should get about 85% of that out.  The only relay that winding works is RL 3 so there must be a misplaced wire or something.

The only other possibility that crosses my mind is a bad relay (RL 3).  If the coil is fowled up or the cap is low in value, then you could have the same problem.  Do you have a cap checker?  Now are you hearing a chatter than continues or is it contact bounce?  When you hit PTT the relay keeps chattering or does it bounce a couple of times and locks in?

All relays good.. If I key the transmit switch the transmitter keys fine.  This ensures all AC relays are working perfect.

If I PTT the rig via the mic, I get chatter.

This means that the Relay that is switching the AC to the relays might be at fault. I replaced it after adjusting and cleaning. No change. Still chatter.

So.. :

No relays are damaged. All are working.
If switched AC transmitter keys fine.
If I use the 6.3 volt AC to Half wave I get 8.3  volts DC clean.
This makes the DC relay click nice with no arc.
AC relays then Chatter before closing.. About 1 second of BUZZ before it latches solid.

I dont see any voltage Drop. No AC ripple.

Question:

1. If I put 6.43 volts AC input to a FULL functional HALF WAVE rectifier, What DC voltage is expected?

Tomorrow, I plan on unhooking DC relay lines and checking coil resistance, This way, I can do Ohms law and get the resistor value I need to Drop 8.3 to 6.0.  I have inserted a 10ohm 2 watt with no luck.  So my guess value must not be correct.

Gito. Thanks alot for your input.  AC switch is fine.. If I throw AC switch, Transmitter works 100%.   This is fine. I can do that.. However, I like to sit back in the chair with a D104 and rag chew..  Whats broken needs to be fixed :)

I can only guess (with all of your help) that the 8.3 is just to much for the DC relay.  The forward Drop of the SR was high. The forward Drop of the silicone diode is LOW.


Clark

Clark,

The DC voltage from a half wave rectifier will drop more quickly under load than a full wave circuit given similar filter capacitance but both will charge the capacitor to the peak voltage (less voltage drop across the rectifier itself).  So under light load the DC output voltage from the half wave rectifier will be greater than the RMS AC input.

Back to the basic problem:  Applying the principle of Occam's razor if the relay system worked normally before the selenium rectifier was replaced and that was all that was done and now you have relay chatter then it must be directly related to the replacement.  It may well be your relay, RL-3, that is the "driver" of the chattering relay is the true fault.  Perhaps your selenium has been slowly dying and the coil voltage to RL-3 has for years been below the nominal value and once you approach the name plate rating coil voltage rating then you have trouble.  To test my theory, put a variable pot in series with the relay coil and adjust the pot to the point where RL-3 just pulls in reliably when the PTT is activated and see if the chatter goes away.  If this is the case, it is likely for years you have been applying less than 6 volts to the relay coil which has masked the problem.  Use your pot to increase the voltage so that there is 6 volts across the coil and see if the chatter returns.  If this is the case then you need to replace or repair RL-3.

Rodger WQ9E

Great Rodger.. Thanks alot for helping me man.

Tomorrow.. I will use my Variable DC supply to kick that relay in.  I will unhook the wires, use clip leads and a switch to safely kick in that relay with 5, 6 and 7 volts ect..    If I get to a lower voltage and it works, Its a simple Resistance measurement to get me to the correct relay.  

Again.. Thanks to all for helping..  There are just some areas where I know when to say when.. This is one of them.  I need help.

Clark

Clark,

Glad to be of help.  Think of this as a learning experience that will make it easy when you hit a similar issue in the future. 

I should have been clearer in my previous response about the DC voltage from a half wave rectifier. 6.3 volts AC is the RMS value from the transformer secondary  but at the peak of the sine wave the voltage is going to be about 1.41 times the RMS value (square root of 2 times RMS to be exact) and it will charge the filter capacitor to this on peaks.  So with no load (PTT not keyed) you should have a DC value of (6.3 - rectifier voltage drop) * 1.41 or around 9 volts but this will drop rapidly under load. 

Rodger WQ9E

Ok.. Thanks again.. The ARRL book is confusing.  The wikki article is even more.. They are saying a lower voltage.. That caused me to believe my Half wave was constructed wrong.  I am 100% is correct now.  I dont understand what the 47K ohms purpose is other then a bleeder.. But why place a bleeder here?  Maybe it provides some load? 

Thanks again for the help.. I am really enjoying the bands right now.. Lots of AM going on.. I put the old Valiant in line and she is running strong..

C

Clark,

I imagine the Wiki article is assuming no filter capacitor so the lower voltage would be correct.  There was a company that used to sell light bulb life extenders that were a half wave rectifier in a button package that you put  into the socket before the bulb was screwed in.  This provided the lower voltage to the bulb extending the life and a similar device was sold for extending the life of the old series string Christmas light bulbs.

But once you add a filter capacitor then you are going to end up with a greater than RMS DC voltage under light loading.  The resistor across the filter cap provides for less change between the no load and full load voltage and will discharge the filter cap when the power is removed.

I will have the Desk KW and Viking 500 on 75 and probably 40 tomorrow night for Heavy Metal.  I have been dealing with a series of phone calls on a consulting project tonight so I have to be tied to the phone and computer instead of the rig.  So much for the holidays :(  but consulting is where I get my "mad money" to feed my vintage gear habit.

Rodger WQ9E

Hi

Clark ,why don't You try to jumper Rl 2 connection ,the relay connection for Relay 3/meaning by pass RL2/not using RL2,if the chatter still exist,than it must be RL3 ,Since relay 3 is an substitute for Switch 2 and switch 3a and 3b in the schematic diagram When using PTT switch ,If I'm not wrong

Gito  

If C 65 is 47 uf. then it is too small.  That cap should be 500 or 600 uf.  I overlooked that value in your original post.

Good catch Jim!

I thought only the rectifier had been replaced and didn't realize the cap had also been changed.  The parts list calls for using a 500 uf @ 6 volts but I would definitely bump up the voltage rating to a safer value.

Clark, the best tool for measuring ripple is your scope set for AC coupling.  A meter set for AC will work I guess but the scope trace really shows the story.  To measure the ripple you have to have the PTT engaged so that the supply is loaded by the relay.

Rodger WQ9E

H Clark,

   Boy both Rodger and Jim have both given you excellent advice. I know this must be frustrating for you. Similar things happen to all of us. Some days I cannot make a wire work!

   Here are a few tidbits to toss up in the air:

* A DC relay will not chatter if the coil excitation is pure DC (when PTT is closed, and relay coil pulls current)
* Measuring the AC ripple with either a DVM (AC mode) or scope is best done when loaded. That means measuring when the relay is energized. With DVM, % ripple is (AC measured/DC measured) * 100. Keep in mind that many DVM's lie when measuring AC with a large DC component. A Scope is better.
* When replacing the SR with a silicon diode, it is an easy mistake to get the diode stripe on the wrong side. The Chump schematic shows it right however. When you diode test with DVM, the cathode (stripe) uses the negative
lead (black) on DVM, but in a rectifier circuit like the Chump, the striped side is plus.
* You said you were going to use a variable DC supply to control the relay. That is an excellent idea Clark. A rough guide might be for a 6 vdc relay coil, to pull in at 4-5 volts, and to drop out at 2-3 volts. You can play with the contact gap (N.O.) and spring tension to change those two points.
 * Relay coils like to be pulsed. For example, for a 6v DC relay the initial turn on could be at 12 volts for 100ms, and then decay to 5-6v thereafter to hold the relay down. This pulsing closes the relay quick, an important thing if you run CW with relay(s) switching various things at a CW rate (NA to your Chump). This would require circuit mods to the Chump.

Jim, W5JO is correct that the capacitor filter should be much higher in value than 47uf (> 10X that value at 10vdc is still a very small and inexpensive cap these days.).

Also measure the DC resistance of the coil. Maybe the relay has a normal value already stamped on the coil. There could be a shorted turn, and maybe the relay failed first..taking out the SR..

* After you get this going again, look up diode commutation to suppress the back EMF spike released when the coil current is interrupted (releasing PTT switch).

Good Luck Clark,
Jim
WD5JKO

Clark with a 1/2 wave rectifier you will get about .45 of the RMS voltage  and normally these circuits are only used in low current applications like you are seeing.  The ripple will be very high and requires a LOT of capacitance to filter.  If you have a 470 uf 16 volt or 25 volt cap, parallel it across the one you have there.  This is the reason I mentioned earlier to check your work after you finish.  It is a mistake I have made in the past and, for us, it was easy to read past the problem. 

   Did you say you put a Silicon diode across the dead Selenium Rectifier ? If so, the SR may be leaky with voltage applied and passing a litle AC along .
  Disregard if this is not the case, I didn't read all of the digression regarding AC/DC relay theory so I may have missed a part where you changed the wiring.

Hi

Yes Roger and Jim using a higher value of like 470 uF,makes the ripple small,but after looking at the part list of Globe 300, it wrote that C65 is a 50uf -25 V Cap,can it be wrong.but there is no problem before (no chattering)

And as I wrote before,if it is caused by the ripple ,than the chattering will not stop ,as long as PTT switch is on.
But Clark wrote the AC relay chatter before closing.about 1 second of buzz before it latches solid.,That means the Chattering had stop,after 1 second

I think something is changing in  the HV power supply of this  Globe,like using  higher Capacity (uF) for the original one .Or the filter choke had shorted.Making a capacitor input power supply.

I have the feeling that  the AC voltage ( 110 V) drops for a part of a second when the PTT switch is pressed ,because the surge current/inrush current  present when filling the Capacitors of the  HV power supply.

At that split second ,the voltage is lower than 110 volt,so the AC relays chatter,
After the HV capacitor is filled / the inrush current stop,the voltage get's to it's  normal voltage,It happens only a part of a second.
Of course I can be wrong ,Just an Idea.


Gito

I am going to put a 1000UF 16 volt cap across the output of the rectifier and give it a go.  All of this has made me go back over my Globe King 500 Restoration documents.  It seems I went down this path with the king also.  In my notes it stated I used a 500UF cap across the output. Someone here, I cant remember who, Told me to put the cap in. That solved the kings chatter. 

I just cant believe I forgot about that mod on the king.  I can remember anything you ever want to know about one subject, But simple things I have done before, I cant recall. 

Gito.  I have 128 volts at the line and it is not sagging much at all.  I normaly run the rig on a 22 amp variac set at 115 volts  At 115, I get exactly 6.3 volts filiment.

C

Really getting Frusterated here.  Today, I cleaned the terminals, wrapped on a new 1000 UF 16 volt cap.  Put a new 1 amp diode. Band towards the cap and DC line.  Still chatters. Its better. But not fixed.  About 30 % of the time, When you key it, The AC relay chatters and buzzes until latching.

If I use the Front panel Switch marked Transmit, The realy never chatters. I can key it over and over.  Key the D104 and it chatters.  I am at a complete loss now.

Clark

Clark,

Try the experiment you proposed earlier with the outboard DC supply for the relay.

With the new higher value capacitor, your loaded voltage across the coil will be even higher than it was so check that also.  Those little DC coils won't stand a lot of over voltage without burning out.

Rodger WQ9E

Hi

Clark when You used the transmit Key,than You by pass Relay 3, (Switch 2 and 3A,3B).
Relay  3 is not energize.So there' no Chatter.

Yes the AC line may looks Constant ,but imagine if there's a 1 ohm resistance in this line,and the transmitter needs  400 /500 watt power input when operating,than it needs about 4 A current,that means there's about 4 A flowing in Your line voltage and a drop of 4 Volt.and I believed when You used the PTT switch the inrush current is much higher say 10 A for a fraction of a second ,than there's 10V drop in the line for a fraction of a second.

This also happen  when We switch an electric Drill,or switching on an "old" TV set,Our light bulb will flicker at that time,meaning there's a dropping voltage in our AC line,since the power needed at switching On time is Higher than in running condition.

And I believed there are resistance in AC line in our house,maybe small,maybe a little high ,because the connection of the AC plug ,the length of the cables .

My point is when We put a temporary high load(PTT ing Your Transmitter),the AC voltage at Our transmitter drops for a part of a second because there's an "R" in Our AC line

So at that time the AC relays will chatter.And when the Load is normal again the AC voltage is normal again and all the AC relay  is operating at the right voltage.
Than the chattering is gone.
My conclusion is based at

1.If our friends wrote ,the chatter is caused by  ripple ,than Relay 2 will always chattering  when the PTT switch is on.But it ceased after a while,so I believed that's not the case.

2.And there's nothing wrong with the AC relay.it works normally,after chattering for a while.

So why AC Relays chatter? because a"low" voltage that supply it


Gito

The AC relay does click when the Transmit switch is thrown. No chatter.  This realy ONLy chatters when I use the Push to talk DC relay.  Makes no sense to me. 

I have measured Voltage. Very minimal Drop. I cant see more then a volt but I am using a Digital meter.

C

Clark, you really don't need over 5-600 uf.  A lot more than that will be a problem like as Rodger has pointed out.  Put a 470 uf in parallel with the 47 you have there.  Provided you have wired everything correctly and do not have a bad wire somewhere then it should work.  When you use the transmit switch you are bypassing the relay so there won't be any chatter because it is not being used.  Try using the switch then key the PTT and see if you hear the chatter.  If you do hear chatter when you key the mic with the transmit switch in the on position, then the keying relay is bad, or you have significant resistance in the keying line somewhere.  The problem may very well be in the microphone.

Sorry about the continuous sentences but this site won't let me put in very many lines before it acts up.

Hi

Clark ,yes the AC relay Clicks ,but which one ,there are 3 AC relay RL1,RL3 and RL4.
If I'm not wrong looking at the schematic,the relay that's clicking is R L! and RL4.
RL3 is not on ,because it's only on when PTT is on(RL2 is Of).
The point contact's is bypassed by Switch 2 (not RL2),Switch3a ,3b (not RL3)'
RL1 and RL4 is feed directly from the AC input via closing SW1,SW2,SW3a,SW3b.

The chattering is present when RL3 is energize via the point contact on RL2,This point  contact  is a switch  for 110 VAC supply  feeding RL3.
As I wrote before in PTT of condition ,to test RL3 ,(not in transmit condition /but must used the PTT switch to transmit )jumper this point contact so RL 3 is energize,without putting RL2 in "action"
Make this jumper as an AC switch,meaning You can switch on and of with this jumper,and see what happens?


Gito

Dirty contacts on the D-104 relay?

D104 is fine. I put a test clip on the back of the mic socket and then shorted it to the chasiss. Still chatters. 

I dont have a 500 UF cap.  I will have to order one.

I used a 500 on the king. It works fine.

If I Throw the transmit switch there is no chatter.  If I then Key the Mic up I get a nice smooth CLICK of the DC relay as normal. This relay is closing nicely.  There is no arc and its nice and clean. 

The AC relay with the multi contacts is the one that chatters. I can see the arc inside it. Its a clear cover Potter Brumfield. It Arcs of a moment then latches.  If I key this with the transmit switch, It simply Closes with NO arc or chatter.

I measured the resistance of the WIRE that runs from this relay up.. It would not make my Fluke beep.  I looked over at the meter and its reading .900.  I need 1.0 to get the  beep.  Maybe I need to Run a new wire here?  I will try to jump it.

c

Clark,

I assume that the .9 on your meter is in ohms which is fine, you don't need a different wire jumper.

With your description of the problem, either relay RL-3 is creating contact bounce due to a coil issue or it has a contact or other mechanical issue.  Since everything works normally when you throw SW-3 that pretty much excludes problems with the other relays since SW-3 is in parallel with the RL-3 contacts and substitutes for it when using manual transmit control.  Since it allows the transmitter to operate normally, then you know the problem has to be in the RL-3 circuit.

To avoid running in circles either connect a known good 6 volt DC supply to the coil of RL-3 and use this to key the relay or you can use a battery holder with 4 AA cells or similar to provide the source.  If you still have problems using this voltage source then you have a problem with the relay (RL-3) itself.  It could be bad contacts or mechanical wear.  But by using a known good source of DC to key the relay coil you can exclude the rectifier/filter capacitor from the equation.  If it works fine with a good 6 volt DC source then you need to add series resistance to make up for the lowered forward resistance of a silicon versus selenium rectifier.

   Clark,

    I don't know what kind of Fluke mater you have, but some only beep when in "continuity mode" when the resistance between the probes is less than 100 ohms. I'm not sure, but maybe the .900 you measured was volts, like what you see on the diode scale. Then again maybe Roger is right and the 0.900 means 0.9 ohms, and this is nothing to worry about.


Join the crowd Clark. My friends marvel at my memory, yet I am quickly realizing that pieces of my memory disappear with no recall. If I go through the attic looking through boxes of radio parts, each part had a story of why I wanted it, and how I obtained it. Then I look at the part 20 years later, and wow, many of the stories are lost ... NO RECALL! Pretty scary  :(


Jim
WD5JKO

Hmm.. On my meter it is one spot for Resistance. Beep is an optional button.  It autoscales.  I just noticed that its not enough to make it beep. 

Tomorrow, I will jumper the wire just for fun.  If it fixes it, Hey, I got wire..

If not, I am going to Set the bench supply to 6.3 volts DC.  Hook it up with jumpers.  Then fire the rig up and send the 6.3 to the DC relay. If it keys solid.  I have more work to do. 

I think that is the next test that makes sense.  Thanks for ALL the help guys.  A simple problem has turned into a long repair.  The good news is the king is working great. 

C

HI

In transmit mode the B+ from 5U4 and HV voltage from 866 is always on,so RL2 and RL3 is not used.

in PTT switch the ground connection of the B+ is off(LV voltage) ,only grounded when relay 3 closes ,also the high voltage transformer is off and switch on by RL3.
So when Relay 3 is activated ,the L.V and HV voltage is on.
That means the LV and HV voltage is switch on and off by the PTT switch ,that activated RL2 ,RL 2 activated RL3 than LV and HV voltage is on.

There's a big difference ,
On Transmit mode the inrush current only happen when the transmit switch  is activated,and stay so/all the time even when We keyed the transmitter since all the RL3 contact point is bypassed  with the transmit Switch.Even it clicks when the PTT switch is used (RL2 and RL 3 is still working but has no influence/no use on the transmit mode)

In PTT mode the LV and HF  on/of is operated  by the PTT switch.
Each time You key the PTT ,There's a inrush current ,because the switching in and of  for the LV and HV power supply.

I still believed there's a voltage drop  on the voltage input of RL 3(110VAC),so the relay won't closed maximally at the moment the PTT is switch  on.(caused by in rush current) or RL3 is changed /defective and needs more voltage to activate it,or  a bad contact points in RL3

Gito

As Gitgo says, change RL 3 and if that doesn't fix it change RL 2.  I am betting on the relay that controls 115 V to the HV transformer now that you have definately eliminated the PTT relay.

Champ is all done.  Changed relays. Still chattered once in a while.  Got fed up, Put the thing back in its case and hauled it back into the shack. Now on 115 volt 22 amp variac, There is no chatter, I guess 128 volts I have at the line in the workshop is just to much. 

Upgrades: 

Added 100UF cap to VFO B+input side.  Stopped all FMing.. Clean and clear, no Freq Drift.
Installed new VFO Bulb thanks to W7TFO.  This is a bulb used in "exit" signs.
Removed Failed SR recitifier, Installed 1amp 1000V diode, New 500UF cap and 47K resistor (half wave rectifier on PTT).
Changed main plate Relay.
Lubricated and Cleaned Fan.
Replaced Two soft Preamp tubes.
Went back to new RCA 866 rectifiers instead of plug in diodes.

Loads up clean to 210 watts AM on Bird 43P meter. 650 watts PEP.

The champ pulls alot of power. When run on a 20 amp houshold line, I got 7 volts of AC Drop when modulated. Now running it on 30 amp Seperate line with 22 amp variac.  1.5 volts AC Drop. 

If you have this problem.. Try a VARIAC before wasting a few weeks trying to stop the chatter!

Thanks to everyone for the lessons and help!

Clark

Its hard to see such a slight voltage increase causing a relay to chatter.
As an experiment, turn the variac up to the 128 volts and see if the chatter comes back.

Any idea why the peak power is down?
You should be getting almost 200 watts more....

Brett

Yep.. It chatters when I plug it into the wall directly.  This is adding ALOT of voltage inside.   At 115 input, No chatter.

I dont think a Champion will ever do 850 pep.  I can remember this one doing a bit more peak with the solid state diodes and at 128 volts in.. But at 115 volts and 866s, Maybe it did 800. It talks around 600 to 650.. Maybe my finals are getting weak after 55 years. 

I just tried it with the variac up.. I am showing 700 straight up on the bird.. But I have to put the Grid at the max setting of 15.  I just dont like pushing this old champ

I decided to go back to 866s and to lower Grid down to the middle range.. Back off on the old girl and enjoy it. If that transformer goes, I am in big trouble.  Also,The Oil can is 1000v unit and with the plug in diodes, i was way over that rating. 


C

 

Hi Carl

Logically when You put a higher DC voltage on a DC relay it won't chatter./maybe it will burnt
I have a different opinion,its not only DC voltage on the relay that goes up but also all LV and HV  power supply goes up,and the transformer are made for 115 VAC right.That makes the AC current in this transformer higher than it supposed to be(using 128 volt,the coil winding/turns is design for 115 VAC).

So the chatter must come from the point contacts of RL3 ,maybe not having the amperage needed at switching on(cause the higher current/inrush current needed using 128VAC in the transformers ),and stop chattering  when the smoothing capacitors is charged(less current flow)

When using the normal voltage (115 VAC) all the current flowing in the transformers /circuit is normal as it is design.
It's just my opinion.

Gito

I agree Gito.  I just put it on a variac on a stiff AC line and no more chatter. 

I used the radio last night for 2 hours. No issues.

C

No, I dont think I would push that trans hard.
What happens if you load it a little lighter, does the positive mod come up?

Brett

Yes. If I load it by the book at 330ma.  It talks about 550 to 600 peak.  If I load it down to 280 to 290, it talks up around 700.

I decided to load it about 290.  Then the plate meter wiggles and does not yank back.


C

I sounds like it wants to run about 250 ma.
The difference in power out would not show on anyones S meter...

Fairly rare radio, no?
I had the opertunity to buy one about 20 years ago but passed as it was over priced and broken.
Neat little rig though, the one I looked at had round corners?
I know they made a lot of different versions of most stuff they built.

Brett

250 might be a little light.    I like to get the Current up. Dont want any arcs in the Mod trans.  I just cruise it around 290 to 300 MA. 

Here is a picture of mine. Now used with an SP600..

Before this line they made a Champion 150 but it was rack mount and plug in coil.

They made this one that I have.. the standard 300.  Then the 300A, Then the 350. 
They all had the same tubes and looked very close to the same.  Its a heavy radio at 120 lbs.  But its really not that bad considering its as powerfull as the GLobe King 400 and that was large and rack mounted with plug in coils. 

I see 1 to 2 a year on ebay.  I missed out on a MINT one.  Lots of them where converted to a single 7094 or other tube Since the AX9909 Amperex finals are like hens teeth.

CLark

That looks like the one I looked at.
I like the globe king 400, at least the RF deck, a well working rig, the power supply and modulator needed a lot of help...but the rf deck seemed fine.

Brett