TX-1 Apache Mod Transformer

[W4RFM]

It seems like I read (maybe in the Apache manual) that the mod iron in an Apache, was built to handle 100 watts of audio, but has a resistor installed to limit the juice.  Am I remembering correctly?

[K6IC]

I'm surprised,  but this data sheet does say 100 W Audio 300-3000 Cycles:
http://www.heathkit-museum.com/ham/hvmtx-1.shtml

Amazin'   Vic

[W4RFM]

Thats pretty healthy looking iron.  I thought that was the case with 750 VDC on a pair of 6CA7's, that cooks pretty well.
Thanks.

[W2PFY]

I have two junker Apaches and two junker DX 100's. The mod transformer looks the same in all of them. According to HLR, The Apache is supposed to have a good sounding mod transformer.

I'll be making one good one out of the two DX100's.

I'll look up the schematic later and see if there is a resistor in there to limit the power.

[K6IC]

About six months ago I did find a site that had Heath schematics,  but that computer CRASHED,  and doing a casual search,  have been unable to find it,  so I have NO schematic.

I'd bet that at 100 W Audio out, the 6CA7's would be really cooking !   But a Philips data sheet I looked at said 100 W max in Class B,  but this is prob not counting any losses in the XFMR,  but still,  quite a feat.

Have heard that the DX-100 Mod XFMRs were made by Peerless (which would be very good),  but would bet that there could have been a number of sources for the Iron in the DXie-100 and TX-1s   ...   and so on.  HH GL  Vic

[W4RFM]

The TX-1 iron all looks like it came from Chicago Transformer.  Of course W.W.II showed us that anybody could copy and simulate a design, but since Heath was in Mich. kinda makes sense.

[K6IC]

I completely agree about Chicago Transformer.  That was my first guess,  but was "corrected" by someone saying the Mod Irom was  Peerless.  Iron is heavy,  and why go out of the neighborhood to buy heavy metal,  OH,  that is something different.

73  Vic

[W4RFM]

By the way, what is up with not being able to find the TX-1 Schematic or manual on the net anymore?

[W2PFY]

As I understand it, someone purchased the rights to the information and threatened to sue anyone for it's unauthorized use??

[k4kyv]

HEATH TX-1 MODULATION APACHE MOD XFMR
PR) 11,000 OHMS P-P CT
S1) 0-500-3000 OHMS @ 250MA DC (175 WATTS)

That's a lot of step-down for a rig with common power supply for modulator and final. Almost 4:1 impedance ratio, and nearly 2:1 turns ratio.  The optimum turns ratio would be more like 1.5:1 or 1.6:1.  I don't see  how you could achieve anywhere close to 100% modulation with that transformer.

Regarding the manual, I'm sure someone would be glad to scan a copy for you.  Whoever bought the original transmitter kit purchased rights to the manual as part of the package.  With the transmitter in possession, you own rights to a copy of the manual, even if the original paper copy is was lost or destroyed. To paraphrase one of our former Presidents, it was "just a goddam piece of paper".

[W4RFM]

Iwant to thank everyone who replied, I now have a copy of the manual thru the magic of the Internet.  Thanks Mack & Peter.  By the way Peter, how is that project coming?
I am going to use the Apache iron with a mutha reactor and shoot for 100 watts with a pair of 807's or 811's.  I love the looks of those bottles. I would use the Russian 6P3S or whatever it is if I knew more about them, 6CA7's are getting way to high. I have a Behringer processor to pump audio into the 12BY7 as per Heathkit.

[W2PFY]

I have a Behringer processor to pump audio into the 12BY7 as per Heathkit.

R U telling me, us that there is a way that was designed by Heathkit to enter the signal at line level to the transmitter?

I'm not doubting you but the computer with all my Heathkit stuff is off the system while I'm playing with another computer trying to get it to recognize a slave drive.

[W4RFM]

No, Heath did not do this, I did. being an old broadcast guy, I wanted to best sounding and loudest AM I could get, so I used one of the holes on the chassis where the SB adapter plugged in (or out), removed that connector, installed a phone jack, and connected it to the input leg of the gain control, pulled out the 12AX7, 6AL5 and 12AU7 that Heath designed, and ran line level audio straight to the gain control.  It sounds pretty good if I say so myself. According to my scope, I could achieve 90 ish % modulation all the time using a discarded broadcast processor, DAP 310 I think was the last thing I had in front of it.

[The Slab Bacon]

FWIW, some years back, I picked up an Apache that had hat all of the iron gutted out of it, and I had a complete set of Dixie 100 Iron. Hmmmm.................. Not a lot of thought process there. I did run into a snag with the modders. Since the impedance of the Dixie 100 mod tranny was not conducive to using a pair of EL-84s, and there was not enough room between the modder sockets for a pair of ST shaped 807s (I didnt have any 5933s at the time). After a little head-scratching and research, I decided to use a pair of 6146s for the modders. (Mainly just because of their physical size.) A pair by a pair, 2 as modders and 2 in the final, whatz not to like. The impedance match / turns ratio was close enough with the Dixie 100 mod iron that it worked just fine. A little tweakage of the screen and grid biass voltages, and it was happy as a clam.     

[WBear2GCR]

I was under the impression that the only real world difference between the two mod irons is/was the turns ratio. The DX-100 being intended for the 807s and the Apache for the 6CA7/EL34 pair... they appear to be the same external physical size, no?

                    _-_-bear

[WBear2GCR]

I stand corrected...

tnx.

           _-_-bear

[W2PFY]

Not only that if you put a DX-100 mod transformer in a TX-1 it wont last very long, it will smoke after a while

I have two junker Apaches and two junker 100's. I stink I'll pull the mod transformer from one of them thar Apaches and plunk it in the 100 that I'm going to give new life if it will fit.

I stand corrected

  Were you standing at the time you were corrected?