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Author Topic: Apache TX-1  (Read 9159 times)
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kc4umo
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« on: August 27, 2014, 07:55:23 PM »

While I am waiting to get all my parts together to homebrew a transmitter i decided to jump on one of my two TX-1's.

This is a lot different than working on a standard hybrid type of HF rig.  I have a lot to learn about it. And since I heard several folks talk about they can sound decent on AM after a few mods I thought what the heck. If I don’t like it I can shelf it or sale it.

When I got these the front panel was very discolored and the brass tuning belts had been long replaced with what appears to be a dog leash.  Also some of the controls would not turn. I then removed the front panel, washed it with dish washing soap, replaced the dog leash belts with new aluminum belts,(hope these will last a while) and cleaned and lubed all the controls.



Although the rig is not too dirty there are places where a good cleaning is needed. If this was a regular size rig I remove the plasitc, spray it down with simple green and scrub it, then place in oven for a bit to dry it.
No way is my wife gonna let me bake this piece of iron in her oven. I just dont want to sprau it and let it dry on its own, water in hard to reach places will cause corrosion and rust on some parts. So have to find an alternative to cleaning.

RF cage


Area around crystal


Overall view of the top



The bottom is not that bad looking. One thing I seen was one of the multi can capacitors had been removed. Someone installed 2 paper caps in the next compartment to replace this with.



Seems I have a lot of reading to do on this transmitter.  So I can learn my way around it. I did a lot of online reading looking for trouble areas of this rig. The manual is very helpful on this.
When I got these in January 2010 I spent a few hours checking and looking it over and fired it up.  At the time I could not find a manual on it.  It later ended up under the counter where it sat until last week end.
When I went through the “first turn on” procedure in the manual. I was doing this while monitoring the frequency on another HF rig and my IRF 1200 looking at the spectrum analyzer. Neither shown any signs of life. However I did see the meter show me almost full scale in HV setting and in the drive setting I can get 1/4th scale on the meter. Grid and final show nothing.

I “think” all tubes are good. But a tester can fool you at times. Neither rig had tubes when I got them. I checked and cleaned switches and relay, checked a few component and wiring. I think my next move is to do an overall voltage check. Maybe this will tell me more of what is working and what is not.

I know the drive from the VFO is low in these rigs but I feel I should have gotten some signal into the spectrum and nearby radio. So all I know the VFO may not be working.

Anyway, I need to search the shop for a missing mic jack. When I took the front panel off I did not re-install it so it is hiding from me.  I am a bit excited about getting this one up and running.  Off to do more manual reading and see if I can get to know this old girl.
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WQ9E
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« Reply #1 on: August 27, 2014, 08:32:47 PM »

Buddy,

It looks like it is cleaning up nicely!  Definitely get it working as intended before trying to modify it.

When you get it to the point of setting it up on phone pay close attention to the instructions on P. 94 of the manual.  The control accessible through the CW key jack should be set so that 100% modulation is provided.  The front panel control is effectively a clipping control and increasing this control will increase the clipping but not the modulation level.  This is a very common mistake made with the TX-1 and a reason why many stock Apaches do sound horrible on the air since the modulation level control is often set wrong and attempts to increase it via the front panel gain control result in ridiculous levels of audio clipping.

I think Johnson and Heathkit were involved in some sort of bizarre contest to design rigs that would sound horrible on phone because of poor adjustment.  The Valiant front panel clipping control goes against convention since minimum clipping occurs at the full clockwise control setting yet people naturally assume it is like a normal RF or AF gain control and minimum would occur at full CCW where clipping is actually around 35 db and sounds attrocious.  Heathkit chose instead to hide a very important control and provided very little info in the manual for proper setup.  It reminds me of a conversation I had with a regional soft drink maker back in the late 70s when "light" i.e. low calorie soft drinks were starting to appear.  Most companies were using darker color or gold cans/labeling for their normal drinks and silver for the light but this company switched the labeling for their standard drinks to a silver label.  When I asked why his response was because everybody else does it the other way...
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Rodger WQ9E
kc4umo
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« Reply #2 on: August 27, 2014, 08:57:56 PM »

Haha, nice story on the drink! Good way to put it. Smiley Thanks for sharing that.

Cleaning it this way is a slow process.  But I like the outcome so far. Tomorrow I need to pick up another tooth brush and cut the bristle back. I am using mostly alcohol and tuner wash then wiping with a damp cloth.  Some areas that show corrosion I am using never dull on those.

I plan on putting this back as stock looking as it can be. Really hate it that a previous owner removed one on the multi can capacitors. What I like doing with vintage gear is re-stuffing the capacitors with a nice grade of computer capacitors. Since one is missing, I will either have to rob one out of the other Apache or take 2 short ones and make a tall one out of it to keep the original look.

I remember reading about the backward controls on the audio.  Seems a guy had moved the control behind the key to the front panel somewhere. I for one will not drill holes to add something to a rig. So perhaps I can find an alternative for that. I think this rig fits the boat anchor category! Man is it heavy.
Thanks for the tips Smiley
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Jim/WA2MER
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« Reply #3 on: August 27, 2014, 09:03:20 PM »

After you get the radio all prettied up and playing properly in stock form, do this: http://www.amwindow.org/tech/htm/w3sccmods.htm.  Cheap, easy to do, and lots of bang for the buck.
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Anything worth doing is worth doing to excess.
Since you have to die anyway, you might as well die from something you like.
kc4umo
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« Reply #4 on: August 27, 2014, 09:14:46 PM »

After you get the radio all prettied up and playing properly in stock form, do this: http://www.amwindow.org/tech/htm/w3sccmods.htm.  Cheap, easy to do, and lots of bang for the buck.

Link took me to google page with lots of listings on the TX1. But I think I found the one you were refering to. A schematic of the audio circuit?


* w3sccmods.gif (20.39 KB, 720x560 - viewed 486 times.)
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Pete, WA2CWA
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« Reply #5 on: August 27, 2014, 09:19:36 PM »

His link (I fixed it) should take you directly to the GIF you posted.
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Pete, WA2CWA - "A Cluttered Desk is a Sign of Genius"
kc4umo
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« Reply #6 on: August 27, 2014, 09:28:00 PM »

His link (I fixed it) should take you directly to the GIF you posted.

Got it, thanks Pete
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Pete, WA2CWA
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« Reply #7 on: August 27, 2014, 09:32:34 PM »

For the Clipping and Gain controls, you could just reverse their positions or just remove the clipping function completely. Gain pot would have to be replaced with one with a shaft.

I got rid of that AC motor/fan over the final cage and replaced it with DC muffin fan that sucks rather then blows as the original fan did. Final cage use to fill up with dust bunnies. If it hasn't been done, most likely all the caps in the VFO should be replaced and all the resistors should be checked. Also replace the 6AU6 with a 6AH6. Check the grid current meter resistor (5.65 ohms) and the plate current meter resistor (.1 ohm). They have a tendency to go poof. Check for carbon tracks on the high and low voltage rectifier sockets. Try not to replace the crystal after you've run the rig for awhile. It's very tight quarters in there and both the 5763 and the 6CL6 get very hot.
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Pete, WA2CWA - "A Cluttered Desk is a Sign of Genius"
kc4umo
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« Reply #8 on: August 27, 2014, 09:44:48 PM »

Sounds like a good idea on moving he pots around. Seems that may have been what the guy did I read about a while ago. I will do that.
I noticed the fan did not seem to move a lot of air, I will change that around.
Thanks Pete for the tips on those resistors.
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kc4umo
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« Reply #9 on: August 28, 2014, 05:43:07 AM »

. If it hasn't been done, most likely all the caps in the VFO should be replaced and all the resistors should be checked. Also replace the 6AU6 with a 6AH6. Check the grid current meter resistor (5.65 ohms) and the plate current meter resistor (.1 ohm). They have a tendency to go poof.

After studying the VFO I see two 510mf caps in there.  These are the old mica caps.  You think silver dip would be ok to use in this circuit?

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VE3LYX
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« Reply #10 on: August 28, 2014, 08:57:30 AM »

When I built the VFO for my Dx60B I used silvermics (330pfs) I have replaced them three times and no longer use them. I switched to disc ceramics. The VFO would quit for no apparent reason and maybe work next time around. Now it works all the time. You also mentioned VFO output being critical. My DX60B (I know it isn't an Apache but it is from the same TeePee) requires a fair amount from its VFO to put out. I was a little surprised how much. Probably because it was designed for a crystal osc originally so it needs an equivalent kick in the pants to operate. So I would say your observation is probably correct. Hope it all works out fine. I will be watching to see when you are up and running.
don
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Don VE3LYX<br />Eng, DE & petite Francais
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« Reply #11 on: August 28, 2014, 09:41:29 AM »

I would check the voltages on the 6AU6. That may give you a better clue as to what component may be faulty in there. Check the VFO alignment procedure in the manual.

Al VE3AJM
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K4RT
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« Reply #12 on: August 28, 2014, 09:55:10 AM »

Buddy,

That's a nice looking TX-1. When I initially fired up my TX-1, I experienced exactly what Rodger described. Setting the GAIN (clipping) pot to about 9 o'clock on the front panel, and with the modulation level adjusted correctly, provided good communications audio.

I initially did the W3SCC mod then made some minor changes later on, and I may make other changes.

73,
Brad
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kc4umo
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« Reply #13 on: August 28, 2014, 11:59:06 AM »

Don,
I will look further into the circuit and see just what is needed. I do have some NOS mica caps but they are pretty old.


Al,
I will have a look at those voltages and see where they are at. Thanks


Brad,
Thanks, All I need is ome of the heath dark green paint for the front bezel, would look super on the out side then.
looking over that mod also.

Got the next 4 days off. Tomorrow I will spend half the day cleaning the shop and moving surplus stuff out to the garage.
Have a FT 401B to finish up for someone else and hope to finish the cleaning on the TX-1. Probably by Saturday I can get down and dirty with the componet checks on this unit.
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Pete, WA2CWA
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« Reply #14 on: August 28, 2014, 12:19:34 PM »

. If it hasn't been done, most likely all the caps in the VFO should be replaced and all the resistors should be checked. Also replace the 6AU6 with a 6AH6. Check the grid current meter resistor (5.65 ohms) and the plate current meter resistor (.1 ohm). They have a tendency to go poof.

After studying the VFO I see two 510mf caps in there.  These are the old mica caps.  You think silver dip would be ok to use in this circuit?



I replaced both of those 510's with silver micas back in the 70's. Still working fine.

I would not diddle with any mods until you get the rig up and running as per specs. Actually the modulator doesn't sound that bad as is if you adjust the gain and clipping controls properly. A very simple, but effective change, would be to just increase the value of the coupling capacitors between each stage.
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« Reply #15 on: August 28, 2014, 10:07:59 PM »

Buddy,

 Did the W3SCC mods on my Apache then sold the rig. After deciding that it had
some of the smoothest audio on the air in the hands of the new owner I knew I
made a big mistake. He sold it to another Ham and when it became available again
I bought it back along with the matching Mohawk with a poorly done rendition of
the ER magazine mods done. After repairing the mods and alignment of the receiver,
it's like a completely different rig.

Good luck with the "Indian"

Dave, W9HW...
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kc4umo
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« Reply #16 on: August 29, 2014, 07:11:45 AM »

Thanks Pete and Dave.
I plan on tearing into the VFO today and replace those caps. Still waiting on my other caps to come in so I can re-stuff the multi cans.

If all goes well today I will have all the voltages checked out, replace a few wires and final cleaning done.
Just had a basket case 940 come in so may have to take some time for that.

I dont plan on doing any mods to the audio untill everything is up to par and the rigs checks out 100%.
Then as soon as the leaves fall I plan on shooting a rope in some 90 feet trees on the back of the lot and ddecide what type of antenna I want to put up that will be dedicated just to AM.
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kc4umo
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« Reply #17 on: September 01, 2014, 09:40:32 PM »

Back on the TX-1 today. Spent most of the day checking components and wiring, and cleaning tube sockets. So far everything is looking good.

I pulled out the second TX-1 today also. It was missing all tubes. Had all in stock except the 2 6CA7's. Have to order them. This radio does not look too bad either.
After checking caps and shorts I plugged it in and flipped the power on. I noticed the relay engaged as soon as the power was switched on. Needed to clean and lube some shafts so took the front panel off. Checked the plate switch to make sure it was not bad and causing the relay to engage, it checked good. Did not get much further due to cleaning this one.

I am sure out of 2 I can get one working soon. Will give me an excuse to drag the National NC-98 out.
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kc4umo
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« Reply #18 on: September 02, 2014, 06:40:05 PM »

The saga continues.....
TX-1 First one.
100 degrees here today. But that was no match for my 4 ton ac in the shop.
When I got home this afternoon, I decided to check all tube pin (all but V1 VFO and V5 V6 final)

V2 pin 6 should be 140 vdc but is at 0, also pin 8 shows -25 and - 110 but checks 0. Not sure what this means but pin 6 has (7) listed in the diagram and pin 8 has ( 8 ) beside it. Page 100 in the manual.

V4 pin 5 has (11) 170 & (12) 70 but checks 0. Pin 6 has the same and checks 0.  Pin 7 (9) -47 (10) 1 checks 0.

All rest of the tubes in the unit are spot on.
So now I have some tracing to do.
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kc4umo
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« Reply #19 on: September 03, 2014, 06:54:21 PM »

A little more progress today. Since I did not have 170 and 140 volts this lead me to V14.
 When I probed pin 8 the 5V4 lit up like a light bulb. The transformer was also a bit warm.

Thinking the worse that maybe the transformer had shorted I pulled the tubepin 5 and pin 4. Pin 4 was dead.  Looking at the schematic I saw M1 and M2. Checked and both were shorted.  Removed them and onstalled 1N4004 diodes.  Replace the 5V4 with a new one  and now have those missing voltages.

So things are slowly coming together one part at a time. Next is to pull the cover from the VFO and check those coltages there.
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kc4umo
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« Reply #20 on: September 03, 2014, 08:50:11 PM »

Went back out in the shop to satify my needs. I am now getting a insication on the meter in drive. Very little though. The other setting is HV which looks good.

I checked tons of voltages. My schematic looks like a rainbow.  At the moment I am still pointing at the VFO circuit. Tomorrow I will tear into it.  I scoped the output of the VFO and got nothing. Not sure if I can see this signal on a scope.  Maybe those 2 510 pf caps are bad causing it to not work. Hope it is that easy.
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