The AM Forum

Hi all,

I am new to boatanchors.  I am working on an Apache TX-1.  I have a few questions

1) The plate current swings down instead of up on modulation.  The manual says that it should swing up

2) What should the windings on the modulations transformers read in ohms on a DC meter

3) The VFO seems to have a second harmonic on 80M that I would like to get rid of


thanks all

Tom - AB3FL

From this recent thread, someone put schizmo up...
http://amfone.net/Amforum/index.php?topic=18411.0

My eyes lie to me sometimes but it looks like 11k on primary and k? on secondary?
Which now begs the questions........., do you have the schematic with your manual?
Whatz the modulated Rf waveform look like on a scope?
Whatz the plate voltage doing?  ???
????....?????.....?????.....?????
More info needed.  Get your meter out and start pluggin' at it.  Check PS's and bias voltages etc.

G/L

I took out the modulation transformer.  The primary is shorted.....from the center tap to one end its 250 ohm from the cetner tap to the other end its 20 ohm

Rewind time for that transformer. Call Gary, WZ1M

Yes Jim, you are correct, 11K primary, 3K secondary, with 500 ohm tap for driving external modulator.   The schizzy in that thread is not real clear, but the one I received in the manual PDF is sharp.

Tom, if you need a copy of the manual, let me know and I will email it.  BTW, I picked up an apache last week, it appears to need a good bit of work.  Haven't tested the iron yet.  It is so heavy, I am thinking about pulling all the iron, and making a rack-mounted  exciter, with separate power supply, for my 304TL rig.  If you do not find a replacement mod tranny for your apache, let me know, if mine is good we could work something out.

73, Rick

thanks!    I have the manual and schematic.    Let me know about the modulation transformer if you are not going to use it......

Tom - AB3FL

OK, I will test it within the next couple days, and pull it if it tests good.

See my posting on modulator tubes for apache. If fixed up correctly the apache can be a very fine vintage transmitter.
DeTimWA1HnyLR

I am planning on doing that mod, but why does the PS have to be solid stated.  I have over 800V on it with the tubes.  My line voltage is high at 125V

Tom - AB3FL

One reason is the voltage drop across the rectumfinders is less under load.

I do agree there, but I already feel bad that I replaced the selenium rectifiers with silicon ones.  I want to try to keep it as original as possible....except for the audio mods.  The nice part about the tubes is the slow start so the transformers and caps don't get that instead high current draw....... 8)

Won't matter on the high voltage since it only comes on when the transmitter is keyed. If you are worried about in-rush on the LV supply install a thermistor on the primary of the tranny. Good to go.

You're already beyond that point, so what's the difference. As long as you don't drill 1/2 holes in the front panel or elsewhere, it's "original" looking.

One other advantage of solid stating the power supplies that everyone else overlooks is that if done properly (disconnecting and capping off the rectumfryer filament leads) it helps reduce the chances of the LV / fil transformer from failing due to an internal zorch over from the rectumfryer winding to one of the other windings due to a HV breakdown. It also leaves you free to use that winding to use for something else if necessary.

I actually had to do this to save the oddball transfoma in my G-76 base station power supply. It had developed an internal short from the HV rectumfryer to one of the other filament windings. It has now worked for years that way.

                                                                          The Slab Bacon

OK.....that is a good reson for me!    I want no Zorches!

Yea, what's more original:

A) A rig with a couple of solid state diode rectifiers and the power transformers intact?


B) A rig with tube rectifiers and a crapped out power tranny?


For extra credit, explain why keeping somethingl is important in a hobby where we're supposed to experiment, modify and tinker.

I chose (A)

  ;D

Enjoy your Apache. It's a nice rig. Catch you on the air.

I pulled the tranny from my beater apache, and tested it.  Checked out fine, so I sent it to Tom.  I will list the measurement info here, in case it might help someone else troubleshooting an old injun in the future......

Resistance measurements:

Plate to Plate 359 ohms, plate to B+  187 ohms, 172 ohms
While the turns on each side of B+ are the same, the diameter of the core is greater for the outside winding section, hence the resistance is higher by 15 ohms on the blue side of the primary.

Yellow to green 57 ohms  green to black 41 ohms, yellow to black (full secondary) 97 ohms.

Voltage measurements with 100 volts 60 cycles applied plate to plate:

Plate to B+ (red)  50 volts on each side, indicating balance.  Secondary voltages: yellow to green 31 v, green to black 21.7 v, yellow to black 53.2 v. 

100 volts full primary to 53.2 volts full secondary is is a turns ratio of 1.88 to 1.  Squaring this to 3.53 gives the impedance ratio.  Assuming 11000 ohms primary, divided by 3.53 equals 3112 ohms secondary.  Rating is 3000 ohms.  This test indicates impedance ratio is correct.   

I ran the transformer with 200 volts plate to plate for 15 minutes, no sound, no heating, therefore no shorted turns.

Steve -- I've always liked that concept. Any suggestions on thermistor type, PN source?

Al

The only problem that I see with solid stating the PS is that the voltages will be way too high


Tom - AB3FL

Pick out the one(s) you need at the link below. Then click on the free samples link.  ;D

http://www.ametherm.com/

There is no correct answer. It was a trick question. It's all up to the individual. In reality, if one was really concerned about originality, they wouldn't even use the equipment, for fear of blowing/burning something.

I still like the "slow start" aspect of the tubes....

WB3HUZ:  Thanks for the link!

Tom - AB3FL

Collins didn't care about instant-on in the PM-2 supply for the KWM-2.

Lives depended on the PM-2 / KWM-2 combination. American lives.

You saying Art Collins didn't know what he was doing?

:-)

The apache LIVES!   I was on 3885 last night to get a quality report.  Not too scratchy, but limited audio bandwidth.  Time to do the W3SCC mods!

thanks for all of the help!

Tom - AB3FL

I may be a no code extra, but I can fix a boatanchor!

Tom said:
Those mods are easy to do and "non-invasive" meaning you don't have to drill or move stuff!

Why not try a TV "damper tube" (diode) in series with the output end of your SS rectifiers? Low drop across it, and gives you the slow turn on, without the limited max current of the 5R4, and since you only need one you now have an "extra" space/socket for whatever you want to put there.

              _-_-bear

I think that I will keep the tubes, but maybe fuse the lines so if there is a short, it will blow the fuse instead of the transformer or anythis else......1A fuses should be good on the LV lines and the HV lines...

Tom - AB3FL

Tom, you'll find that around here (as opposed to some other forums), it matters not what your code ability may or may not be.  See my signature below  ;D

It's how you progress, learn, and help others that counts more!  Welcome to AM.

Mods have been done......some of a qso the other night

me: I am on a Scratchy Apache with the W3SCC mods
other: Well....that Apache is no longer scratchy....It sounds great

This was from someone running Berhinger mics, sound processing, etc.   

I am now working on a Mohawk

Tom -AB3FL

God save your soul in polishing that turd

There was a 3-part article in Electric Radio some years ago in getting the Mohack up to scratch.   Lot of work, but it is a very cool looking receiver and would be a worthy effort to match your Apache.

Yes, they are certainly an attractive pair. Polish the knobs in a tumbler... very easy and impressive results. (see Eastwood.com for a tumbler)

The Mohawk actually looks perfect....Not a scratch on it (it was painted) and shiney chrome knobs.  I have the EM issues with the K6AD mods which most of them are already done to it.  The only problem that I am having with it is static from somewhere in the 50KC IF section.  I will post pictures soon.

Tom - AB3FL

Wow, yuo're really going to town with that pair - congrats!  Gonna be a sweet looking and performing station when you're done.

I do love my pair. Maybe an Indian to Indian QSO sometime after I get my wire up,,,
73! Norm K7NCR

Most definetly.....

as i promised.....Here is station AB3FL.....

Also (I know lame), but does anyone know of a digital frequency display unit that can interface to the Mohawk.   I can use my pro III, but I would rather have something directly connected to the Mohawk.  All 3 units work perfectly.....I have received great reports on the apache.   If you would like to sked a QSO, please let me know.   I really want to know how well I did.....

thanks

Tom - AB3FL.......No Code Extra, but I can restore, fix, operate a boatanchor!

Which is really all we care about here, Tom. Working with the stuff and being on the air beats the hell out of sitting around festering over the way things 'should' be, used to be, etc. Life is short, radio is fun.

Nice looking station, hope to work you once I get back on the air. In case you don't already realize it, beware: the old gear really grows on you, and around you, and grows, and grows...

Tom, great little inexpensive freq counter kit that is programmable to ANY IF freq

http://www.pongrance.com/

And like I said before, it matters not your CW ability on this forum.  You passed the exam fair 'n' square - no need to be apologetic about being a NCE.  You are a prime example of why the bitter old buzzards pissing and moaning about the exit of the CW exam are dead wrong.

thanks all.....I am probably one of the youngest OM running boatanchors.....

Tom - AB3FL - 1971 vintage

got me beat at 1963.  8)

ALthough I'm somewhat of an old buzzard now I got into boatanchors at 15 with the purchase of a cherry NC-173.

You done good with that combo.  Especially the Mo-hack - those mods are quite extensive. 

Hope to hear ya on the air.  Check out 3733 every afternoon, bunch of us get together down there.

still working on the mohawk mods.  I have most of them done.  I need to get the fets and the zeners for the agc and detector mods.. but I finally found them, so next week that will be done.  Also as for temp compensation mods, I might not even do them.  They look a little too extensive and time consuming, just so you dont have to move the vfo a little

Tom - AB3FL

A giant PITA temp compensating any VFO.  If you're gonna use it mostly on the lower bands there's probably no need to do it.

yeah.....i intend to use it mainly on 80 and 40.   I have the PRO III for the higher bands

Tom - AB3FL

I will look for you allo on 3733 today

bout 4 or 5 you should hear some activity down there