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Author Topic: Apache TX-1 HV Short  (Read 26638 times)
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oldsalt
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« Reply #25 on: February 01, 2008, 04:15:41 PM »

GFZ, there are two wires from the choke: a red and a black.  The black wire is soldered to an insulated post bolted to the chassis.  This point is the middle of the diode string.  The red lead is connected to the large double section resistor (bleeder?)  Are you saying to reverse these two wires?

Russ
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« Reply #26 on: February 01, 2008, 10:08:40 PM »

Russ,

As far as I have heard the HV choke shorting to the core or case is not a common failure point in the TX-1 and unless you have good reason to believe that it is shorted or "leaking" to ground I would leave the power supply as designed by Heathkit.  Realistically, this choke is not at that high a voltage above ground since this is a transmitter and not a 4-1000 amplifier and the choke was designed/specified for this type of service.   Again, I would caution you that you may run into an issue if the plate transformer in the TX-1 was designed to have the center tap at or very near ground or else you may run into an internal arc; this is the same reason that some center tap transformers are not usable in a full wave bridge as the center tap was expected to be at near zero volts.  Furthermore, if the choke ever opens up then the center tap is going to be at a very high potential to ground and this may well lead to the demise of the transformer if it was not designed for this voltage level on the center tap.

At the very least I would want to get the rig to the point where identified problems (such as the rectifier problem you found) have been fixed and then troubleshoot from there.  If you start making a lot of changes now it will be difficult for you to determine whether the original problem has been fixed or if additional problems were created during modifications.

If you do want to go ahead with negative lead filtering then you will need to lift the center tap of the plate transformer (T-2) from ground, disconnect choke L-30 from its connections to V-16 pin 2 (or where it connects to the current rectifier string) and where it connects to R-52, C-1, and the "bottom" of the modulation transformer, and then re-connect L-30 between the center tap of T-2 and ground.  You will then have to place a jumper between V-16 pin 2 (or where the choke was originally connected) and the junction point for R-52, C-1, etc.

Rodger

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oldsalt
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« Reply #27 on: February 07, 2008, 01:28:49 PM »

Time for an update.  Been busy studying the manual and relating the rig's wiring to the schematic.  It's fun but has been a sharper learning curve that previously thought.  Been identifying parts, numbering conventions and component color codes, and comparing physical layout to the schematic. 

The electrolytics and diodes have been replaced in the Apache.  I used the convention of  calling the marked ends of these components as the cathode or negative.  Attention was given to polarity shown on the schematic as well as when the old part was unsoldered.

Found one of the two 15K/5 Watt resistors to be 200K ohms+.  I replaced both with what I remember as being a 25K/20 watt wirewound milatary surplus type.  Diameter is .5" with a hollow core.  Is this OK to use?

The plate switch was replaced with a 3 amp Radio Shack.  The original specs call for 6 amps or so.  Is 3 amps suitable?

Upon firing up the AC to test my work (removed all tubes), the lights came on a little hum and a minute puff of smoke came from the modulator compartment.  I hope it isn't the audio choke or worse, the LV filter choke.  I double checked wiring from that point and tired again.

When I click on the plate switch to operate, the relay does not click in.  There is 120VAC on both lugs measured from chassis ground to each lug.  The lugs traced back to strip JM are as shown in the pictorial.  The relay tested fine when removing the relay and connecting to a 120 power cord.

No HV at all.  There is a 5 VAC and a -200 volts reading in the left and right power supply compartments.

What should I do next?  May I have your help?

Russ

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« Reply #28 on: February 08, 2008, 11:24:47 AM »

Time for an update.  Been busy studying the manual and relating the rig's wiring to the schematic.  It's fun but has been a sharper learning curve that previously thought.  Been identifying parts, numbering conventions and component color codes, and comparing physical layout to the schematic. 

The electrolytics and diodes have been replaced in the Apache.  I used the convention of  calling the marked ends of these components as the cathode or negative.  Attention was given to polarity shown on the schematic as well as when the old part was unsoldered.

Found one of the two 15K/5 Watt resistors to be 200K ohms+.  I replaced both with what I remember as being a 25K/20 watt wirewound milatary surplus type.  Diameter is .5" with a hollow core.  Is this OK to use?

That would depend on where it is in the schematic and what its function is/was.
The type of resistor is fine. IF the value is correct or reasonable depends on what the resistor is supposed to be doing.

Quote
The plate switch was replaced with a 3 amp Radio Shack.  The original specs call for 6 amps or so.  Is 3 amps suitable?

Probably not for long.
But if it is a DPDT you can just parallel two contacts!  Grin

Quote
Upon firing up the AC to test my work (removed all tubes), the lights came on a little hum and a minute puff of smoke came from the modulator compartment.  I hope it isn't the audio choke or worse, the LV filter choke.  I double checked wiring from that point and tired again.

Well, if there was a puff of smoke something fried.
I'd look for shorts to ground with an ohmeter. Also, look for any signs of bulging caps, or cracked or burnt resistors. Your nose can help the search. Sniff it out - UNPLUGGED FROM THE AC. Something burnt. Find it.

Next step is to go back to the basic troubleshooting method I described before.
There are three main power supplies. B+, LV & bias.
You need to fire them up one at a time. That will require desoldering the AC going in to the transformer you are not testing. I'd start by testing the LV only.

IF you had all the tubes out, and the PS is using tube rectifiers, there was no connection to the filters, and no DC. Sounds like you had the rectifiers in place. That's a no-no in an unknown rig, unless you don't mind smoke.

Test one section at a time.

So you have to check the AC out of the transformers, THEN put a rectifier in place, preferably without there being any of a connection OUT of the PS filter... a series'd 100 watt incandescant lightbulb with the AC mains, OR better still a "Variac" (tm General Radio) to bring up the mains slowly is the best idea. That limits the current and voltage available, for testing. A dead short and the bulb will show full brightness, otherwise it will share current with the transformer, which is not drawing much current without a load... so probably not full brightness...



Quote
When I click on the plate switch to operate, the relay does not click in.  There is 120VAC on both lugs measured from chassis ground to each lug.  The lugs traced back to strip JM are as shown in the pictorial.  The relay tested fine when removing the relay and connecting to a 120 power cord.

No HV at all.  There is a 5 VAC and a -200 volts reading in the left and right power supply compartments.

Again, the idea is to break down the testing to specific supplies and go from the AC input out through the filter to determine that the power supplies will make the requisite voltages.

Without any other circuitry connected to the supplies the voltages will be higher than shown in the "book" - but it will work. After you have power supply voltages working, you can then connect each supply to the rest of the circuitry, ONE at a time - testing the related circuitry for function. Start with the LV DC supply and you can test the things that it supplies. Then check the bias supply & HV power supply. THEN try it connected to the circuitry in the rest of the rig. WITHOUT THE 6146 or 6CA7 tubes! That way you get to not draw any real current and see if any of the passive components want to smoke. Again, a series bulb or variac is a good idea to both keep the voltages down where they want to run and to limit current in case of a dead short.

Next, you can check to see that the relay works, and that there is B+ being supplied to the 6146 plate caps in CW, and then you can try AM and see if B+ flows through the mod iron to the plates of the 6CA7s...

You can test the VFO's operation with only the LV supply, for example...

I'd guess that you may have put a cap in backwards, although that's just a guess.



Quote
What should I do next?  May I have your help?

Russ


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oldsalt
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« Reply #29 on: February 08, 2008, 03:21:44 PM »

Appreciate your response, Bear.  A structured approach is much needed!

Do you recommend I plug back in all tubes except modulator and RF tubes ?

The series light bulb...  If I follow you correctly, I can use an incandescent bulb to prevent higher voltage and current load capacity, and as a visual indicator?

You say, lift all of the AC input leads except for the LV transformer...  I can do that.

By the way, I replaced the Heath AC line power cord with a 3- wire 16 gauge cord with the green wire going to chassis ground.  Added a chassis mounted fuse holder and wired to the input line caps on rear apron.  Is this the proper method?  There was no double fuse AC plug when I got the TX-1.

Can I use 3 amp fuses for testing purposes?  I've got a couple of 7 amp.

I'll replace the plate switch with a higher amperage rating.

The HV filter cap(s) has a series of "O's" within a color band down the length of the cap.  The numerous other caps replaced have a series of dashes to indicate the negative terminal.  Is there and significance to the O vs. dash, such as plus and minus?  Or is the marking convention for Xicon caps universal in that a banded terminal is always negative?

Thanks.


Russ


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« Reply #30 on: February 08, 2008, 03:54:03 PM »

Appreciate your response, Bear.  A structured approach is much needed!

Do you recommend I plug back in all tubes except modulator and RF tubes ?

Not exactly, please review what I wrote before... first get the power supplies operational and certain. Then sequentially fire up the LV supply with the smaller tubes and make sure that they are working, such as the VFO. Then fire up the HV supply WITHOUT the larger tubes that use the B+ voltage. Make certain that screen voltage(s) and B+ and bias is being applied to the proper pins and locations. Only then try to put in either the outputs or the modulator tubes to test them.

Quote
The series light bulb...  If I follow you correctly, I can use an incandescent bulb to prevent higher voltage and current load capacity, and as a visual indicator?

Yes, but an ammeter and Variac are preferable, as is an ammeter with the bulb.

Quote
You say, lift all of the AC input leads except for the LV transformer...  I can do that.

Well not all of the wires! Just one leg of the input to a given transformer is needed, or if there is no voltage applied until you flip a switch (and the switch works) then you don't need to do anything on that one.  Grin

Quote
By the way, I replaced the Heath AC line power cord with a 3- wire 16 gauge cord with the green wire going to chassis ground.  Added a chassis mounted fuse holder and wired to the input line caps on rear apron.  Is this the proper method?  There was no double fuse AC plug when I got the TX-1.

In theory this is fine. Wired what to the input line caps? you mean the feed-throughs for the AC mains? Fine. Some ops may not prefer the AC grounded chassis because of RF issues, but that is for another day...

Quote
Can I use 3 amp fuses for testing purposes?  I've got a couple of 7 amp.
Sure, if that is less than the thing draws when you turn it on or flip a switch...

Quote
I'll replace the plate switch with a higher amperage rating.

The HV filter cap(s) has a series of "O's" within a color band down the length of the cap.  The numerous other caps replaced have a series of dashes to indicate the negative terminal.  Is there and significance to the O vs. dash, such as plus and minus?  Or is the marking convention for Xicon caps universal in that a banded terminal is always negative?
Thanks.


Russ

Dunno. Look at the caps carefully, most caps have either a + or a " - " indication and in the case of those that have the indication all along the length, an arrow points.

Fwiw, most caps are built with the "can" being negative, the " + " terminal is usually in the middle of a plastic or rubber circle and the connection is usually a nub with a wire coming out - in the case of an Axial lead cap. The radial lead type with the terminals on one end are usually labeled or indicated by a symbol or color via a legend on the side of the cap.

You can check the Xicon website for that specific cap's labeling I would expect.

Or post a jpeg of it here and someone will figure it out...



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oldsalt
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« Reply #31 on: February 08, 2008, 04:49:54 PM »

Bear, yes, the caps are the feed-throughs on the back of the rig.

The VOM has an amp meter function: small milliamp ranges up to 20 amps.  I'll need some instruction on testing current (AC and DC), such as lead polarity in a DC circuit.  I'm assuming the meter will be in series with the circuit and completing the path if the leads are attached to give a forward meter reading.  Wheras, AC current the leads are interchangeable with the test points.

Appreciate all the help on this forum.  And the patience!

Back to the Apache.

Russ
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« Reply #32 on: February 08, 2008, 05:18:15 PM »


Hey Russ,

Would ya mind sharing your callsign with us?
That would be nice, if you would...

And yes, you seem to have the right idea on the Ammeter...

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oldsalt
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« Reply #33 on: February 08, 2008, 07:14:43 PM »

Call sign is WA1JFX, located in Maine, Bear.

I just replaced the plate switch with a 10 amp DPDT toggle.  Also wired a light bulb in series on one side of the AC line.

Powered up the rig, moved plate switch to transmit to hear the relay click in and see dim light from the incandescent lamp.  I must have made a mistake with wiring the first replacement switch.

I'll get some readings on low voltage and let you know what I find.


Russ
WA1JFX
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oldsalt
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« Reply #34 on: February 08, 2008, 09:53:25 PM »

Hi Mack.

Yes, I'm enjoying the challenge and realize I've got a lot of learning in store.  Thank my lucky stars for this forum!

It's something in the modulator section or close by.  That's where the smoke signal and sound came from I believe.

I plugged in all the tubes except finals and powered up the rig.  The series light bulb glowed dimly.   Then switch on plate switch to hear no relay click.  And the light bulb became quite bright, so I shut off the AC.

When pulling all of the tubes in the modulator compartment sockets and flipping the plate switch on, the relay clicked and the bulb had a dim glow.  I know, Bear, this is not what you said to do.  So, I better begin following orders or I'm going to pooch something else.


Russ
WA1JFX.

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« Reply #35 on: February 09, 2008, 12:13:47 AM »

I guess the lightbulb might glow brightly if sufficient current is being drawn by the rig. May not be a fault...

If the rig is supposed to draw 3 amps when keyed, that would be ~300 watts. So it might be reasonable for the 100 watt bulb to be pretty darn bright. Of course, it is tough to pull 300 watts through a 100 watt light bulb!  Roll Eyes Roll Eyes

Hmmm... so that might be how the bulb limits the current... I'm not sure.

You might want to test the modulator or else test the VFO and then key it for CW only, for a first smoke test.

Resistors tend to make smoke, fyi... especially carbon resistors. The show the heat by having the colors change. I just proved that point in the VFO in my Valiant Duece earlier today.  Grin

How close are you to Timtron up thar in Maine??

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oldsalt
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« Reply #36 on: February 09, 2008, 09:54:50 AM »

Tim HLR is about 80 miles away from me, Bear.

Russ
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« Reply #37 on: February 09, 2008, 10:21:07 AM »

Hey Russ,

If ur really having too much trouble with it, and depending on what sort of horse and buggy roads you folks have up in Maine, it might be worth the trip to Timtronia and have the expoit have an "up close and personal" meeting with ur 'Pache?? That is, if he is willing...

You own a 'scope Russ?

That would help you a bunch.

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oldsalt
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« Reply #38 on: February 09, 2008, 11:59:32 PM »

Nope, don't own a scope, Bear.

You're right on the word trouble and I surely would be better off to have Timtron's expertise, so that's what I will work on.

Thank you.

Russ
WA1JFX

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« Reply #39 on: February 10, 2008, 03:01:20 PM »

Negative lead filter choke. Remove Choke leads and and connect the two points with an insulated wire. Now find the HV center tap coming out of the HV transformer.
Disconnect the lead from the transformer. Connect the CT lead from the HV transformer to one lead of the Choke. Connect the other lead of the choke to the place you just removed the HV transformer CT from.  This puts the choke in the negative lead of the supply.
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« Reply #40 on: February 10, 2008, 11:21:58 PM »

Russ,

Don't give up hope yet!

I supposedly know something about what I am doing... yet on an Apache that is still boots up on my bench I spent at least 2-3 days in the rear corner (underside of the chassis) near where the AC line comes in trying to find a good reason that the voltages that were going to the modulator section were just plain wrong when everything looked absolutely correctly wired and perfect!!

Well, it turned out that the problem was very high on the list of all things that can go wrong - actually the number one thing that goes wrong with kits: a solder connection!

Fyi, the list is: (skipping outright miswiring)
1- solder connections
2- capacitors
3- resistors
4- active devices: tubes or transistors
5- everything else

What was wrong with the supply was that the cluster of wires that went back to ground via that solder type terminal strip that hangs on the inside of the rear chassis side has multiple wires on it. At least one of them was held in place and looked perfectly fine under close inspection (magnifying glass!). BUT, you could only see it from the top, and the wire(s) that counted most (center tap return) was actually held in place by onlyrosin!! Looked good, held well, but wasn't exactly electrically connected, there was a lot of leakage, so it sort of worked!  Roll Eyes 

I got seriously PO'd at it after that, and haven't gone back to it yet... I will though.

I figure the alignment of the planets needs to shift a bit first...  Wink

So, don't bail on it yet!
Remember it did work, and it can work!

You can find the problem(s) - and when ur done, you'll really know your rig well, and if something ever goes south again, you'll really know what it is and how to fix it!  Grin Grin

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« Reply #41 on: February 11, 2008, 04:49:13 PM »

Everything Bear said with one addition:

the ability for you to solder and solder well, using the correct tool for the job, from 3 wire grounded 30 watt iron with static mat for IC's and hollow state to 300 watt gun for soldering/bonding heavy rf strap direct to chassis is 50% of the game. After that comes inspection ability, to be able to see or smell or hear what's wrong, followed by everything else. You'll get there.


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« Reply #42 on: February 11, 2008, 05:22:00 PM »

Russ, if you cant get Tim to help you out, bring it up to the Bangor area. I will be glad to help you out on a weekend.
Regards,
Gary...WZ1M
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oldsalt
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« Reply #43 on: February 11, 2008, 09:11:15 PM »

Thanks Bear, Derb, and Gary for your offer to help.

Lifted one leg of each transformer secondary LV abd HV.  Got a variety of low voltages" 5 volts; 6 volts; 125; 320; 600.  The HV windings intially read in excess of 1000 volts on my VOM highest range of 1000 volts.  But after several tests the HV AC disappeared.  When I turn on the plate switch the relay clicks and the series light bulb emits a dim glow but no HV.

Resistance between both HV xfmr red leads is 65 ohms; 30 ohms either side of center tap.

Suppose the HV transformer is bad?

I've gone over the Apache head to tail and corrected several errors I made,  The process of removing one leg and then testing for a short and presence of voltage has been a good exercise.  The schematic is not as foreign to me as it was several weeks ago.

Russ
WA1JFX
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« Reply #44 on: February 11, 2008, 11:52:31 PM »

Russ...!

Please pull out a handbook and read the section on types of rectification, filters and power supplies!!

Then identify the types of set ups used in your Apache.

You'll be wanting to check the AC on the secondaries - according to both what the handbook says the voltage relationships will be AND (if you have the manual) according to what the test voltages page says by Heath!

There are going to be 5vac, 6.3vac, and maybe 12vac filament windings.
A bias voltage is going to have a winding too.

But ur looking for the secondaries that provide "juice" to the rectifiers first - IF ur "lifting" transformer legs.

But - You don't need to do that - just pull the rectifier tubes and check the voltages on the bottom side or from the top side, once you ID the pins on the rectifier sockets.

That will tell you if the AC is present properly.

With the rectifiers in place, and the wires going AWAY from the filter components (caps and  if used, chokes) removed you can check the DC voltages.

Again this is where I suggested a bulb in series to knock down the unloaded DC voltages enough so that you don't over voltage the capacitors...

Doing this ought to take about an hour maximum, including identifying the various supplies and where you want to go to test the voltages.

IF THERE ARE NO BIG TUBES IN THE RIG THERE IS NOTHING TO DRAW CURRENT.

You can also just test the B+ voltage by merely throwing the plate/transmit switch in the CW position, and looking for B+ on the plate caps, or off the RF Choke or underneath the chassis. You'll need the rectifier tubes for the B+ in place to see DC from that supply.

There are TWO supplies: a high voltage (~700vdc or so) and a low voltage (max voltage is (~300vdc, iirc). Separate transformers, separate rectifiers.

Test separately.
Refer to schematic for typical voltages.

The low voltage first.
The HV second.
Rectifiers removed in the same order for AC voltages, then with the rectifiers installed, respectively for DC. That means you test the LV AC and then the LV DC. Then the HV AC, then the HV DC.

Once those voltages are found to be ok - then you can go forward and test the functionality of the RF section, then the Modulator section.

HANDS OUT OF THE RIG AT ALL TIMES!

Read the handbook section on how power supply rectification and filtering is set up before doing anything more. My 2 cents worth...

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« Reply #45 on: February 17, 2008, 05:41:38 PM »

Hey All! Here's my 2 cents in this pot. I tried to load up the Apache today to run with the SB-10 on the vintage SSB nets. I'll I got was low B+ and a blown fuse. So I yarded it out of the cabinet and on to the bench. Someone had already replaced the HV tube sockets with ceramic ones. No short apparent when the rectifiers were pulled. I lifted the plate caps on the finals, and still had the short. Then God must have smiled on me today, as the very next item checked proved to be the problem. C49, the bypass cap at the base of the PA plate choke, is shorted. I removed the screw from where the choke attaches to the side of the final cage, and with the cap's grounded lug floating, NO SHORT! The rig loads up as good as ever! Maybe this will help someone else along the HV way of the ol' Apache. I sure am lucky that it was this simple, and I stumbled on the problem with a minimum of diassembly. I don't know if you checked the HV  circuits at this end, but it may be worth a try. I will definitely use a better rated cap for the replacement. Good luck!
Norm K7NCR
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« Reply #46 on: February 21, 2008, 09:12:42 AM »

Good deal, Norm, thank you!  I'm glad to hear of the victory.  I'll check the bypass cap on my TX-1 here.

I've got the rig so it doesn't pop fuses anymore.  Just discovered by disconnecting one of the AC primary leads to the plate power supply that I'm able to tune the driver and grid.  But if I connect the HV I'm not able to tune the driver and there is excessive voltage and current readings on the rig's meter without throwing the plate switch.

This new revelation is encouraging.  Hopefully, I can soon get the rig fixed and on the air with the help of one of the Maine ham.  I'm a workin on that, and will let you all know of the outcome.

**********

I picked up a 1994 ARRL handbook.  Wow, this is serious business.  The technical aspects are a science for sure.  Congratulations to all of you who have learned and thanks for sharing your time so far.

Russ  WA!JFX.



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« Reply #47 on: February 22, 2008, 11:58:46 PM »

Russ,

For working on units that use tubes a pre ~1969 handbook is best. Late 50s and early 60's are pretty good that way.

As far as your HV supply... obviously there is some issue relating the HV supply.

Looking at the schematic, comments refer to the HV supply:

If you remove V16 and V15, there will be no DC.
So, if the unit does not blow fuses then the HV tranny is probably ok.
You should be finding the filament voltage (AC) on pins 2 & 8 for each rectifier tube.
Next, with the unit OFF and unplugged from the AC mains, and checking the voltages using a DC voltmeter at the junction of C1 and L30 to ground, and then between C1 and C2 to ground, IF it is zero, then: change to ohms and look for ~15kohms (may rise to about that after a few seconds or so) across C1 and also across C2. IF the ohms reading seems to be significantly below 15kohms (the shunting bleeder resistor value) then you have likely a shorted filter cap.

You can REMOVE the wires that goes from the junction of C1,R51,L30  and measure the B+ voltage there with the rectifiers put back in. The plate switch turns on the primary of the HV transformer. Switch off, no HV.

Looks to me that the plate meter is actually a CATHODE meter, so if you remove the 6146 tubes (again, make 100% certain there is no B+ on the plate caps before you touch them - UNIT UNPLUGGED!) there should be NO meter movement.

R20 looks like the shunt that the plate meter measures.

So, if the thing draws HV with the 6146 removed, but works ok with that wire going to the C1 junction removed it has to be some sort of short elsewhere.

Looking at the schematic, it appears that the B+ is fed from the C1/L30 junction to the bottom of the Mod iron (T5), and to the mode switch M7 - which is in the CW position in the schematic - meaning that that switch essentially is shorting the mod iron by applying the B+ to both sides of the winding. In AM it will apply the B+ to only the lower side in the schematic. See?

So, no matter what, IF you remove the wire that comes off T5's secondary (the side that we're feeding in the B+) and which then goes to the junction of L16 and R29, then nothing is going to the RF section.

That wire is pretty easy to find, because it goes to the bottom of the RF choke in the RF final tank compartment and is DC connected to the plate caps of the 6146. So you can take the ohmeter and look for it on the bottom of the chassis (again assuming no DC present, and checked for first). Then desolder the wire either on the bottom of the RF choke or at the terminal strip that is likely near the mod iron. Then if you fire up the B+ with the mod tubes removed, the only things in the circuit are the mod iron and what comes from the rectifier tubes.

This is how to isolate the location of the fault.

Although it may just be that pesky RF bypass cap - C49.

So you do this stepwise... either from the V15/16 side forward or back from the 6146s, then to the V12/11 combo, then back to the filter caps, then to the V15/V16...

Ok? Make sense now??

             _-_-bear

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_-_- bear WB2GCR                   http://www.bearlabs.com
oldsalt
Guest
« Reply #48 on: March 09, 2008, 07:59:40 PM »

Good news!  Today I got the Apache to produce 100+ watts output into a light bulb and wattmeter.

For the past two weeks, I've gone through the rig checking component values and tracing the wiring.  There were a couple of bad resistors, a bad 12BY7 and some of my own cold solder joints.

Last night I blew a cap.  I had plugged in the 5V4 wrong - the octal key pin was broken off.  Today the filament let go in the 5V4, so I pulled the tube and soldered a 1N5408 on each 340 volt HV lead of the low-voltage B+ at the pins on the socket and soldered them togeter for a B+ feed to the filter choke and caps.  The voltage measured 466 volts DC; the schematic calls for 370.  Can someone tell me how to properly solid state the LV B+ (5V4)?

After tuning up the rig for full output, smoke came out of the LV filter choke.  This prompted me to think I had used the wrong rated diodes and too much voltage was getting into the circuit, so I cut the diodes tie-point so only one side of the transformer and one diode in series was feeding the filter choke.

I let the filter choke cool down for an hour and fired the rig up again.  I now measure 444 VDC at the filter choke and caps; still too high, but the rig still puts out 100 watts on CW and AM.

The rig has been powered up for testing while the chassis is in a vertical plane vs horizontal.  I don't know if this is hard on the internal tube parts, such as sagging filaments, etc.

Russ
WA1JFX



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