Heathkit TX-1 and RX-1

[WZ1M]

I just purchased a Heathkit TX-1 and the RX-1 with matching speaker. Both of these units are a 9 on the 10 scale. The TX-1 has a new dial drum I have to install. Done a few of the recomended mods on the RX-1 along with solid state the first rf amp and the 6BJ7. I found several unsolder joints which is probably why this was hardly used. It is now a pretty good performer and this coming weekend will dig into the TX-1. To top this all of, I paid $100.00 for all and it was delievered. How can you beat that.
Gary

[WQ9E]

Gary,

Sounds like you got a great deal.  I have a complete Indians setup (TX-1, RX-1, SB-10, KL-1, 6 and 2 converters) and they make a nice vintage multi-mode station.

In general, you want to run the IF gain well below its maximum setting.  Many vintage receivers have an additional IF gain control but it is internal and meant to be set as part of the alignment.  Heathkit (mistakenly?) trusted the builder/user to know how to operate it and that doesn't meaning running it wide open which makes the receiver very noisy and generally a mediocre performer. 

With the TX-1 read carefully about the setting of the two controls (one of which is accessible through the key jack) for properly setting up the audio system.  Although the Apache was designed for communications audio even unmodified it is acceptable (for communications and not hifi) when the audio is properly adjusted.   

My only complaint about the pair is no 160 meter coverage with the TX-1 (and Chippewa amp).

[WZ1M]

Roger, tnx for the tips. I noticed by solid stateing the first rf amp that the floor noise level decreased a bit. The TX-1 power supply section had been butchered and now in the process of redoing this. I was surprised to see the RX-1 speaker cabinet was made of wood.
Regards,
Gary

[w3jn]

It's DEFINITELY worth it.  Probably the prettiest vintage station ever.

A stock Mohack is a really poor receiver, though.  However looks like someone went to the effort of improving it.  If it works to your satisfaction, leave it alone.  There was a series of articles in Electric Radio some years ago detailing some mods to the audio, AGC, product detector, etc to make it usable - perhaps those are them although as I recall there wasn't any solid stating of the toobs.  Joe WA2PJP did some mods on his and I was astounded at how great the RX performed as compared to the stock one I had years ago.

[W3GMS]

Gary,
You got a great deal on the TX-1 and RX-1.  I have both pieces as well and they are a lot of fun to operate.  If you every want to broaden out the audio the TX-1 can sound very good.  Its not bad stock for what it was designed to do, but the rig is capable of some very FB audio indeed.  If your going to do just two simple things to the audio, the first thing to do is to get rid of that very tiny very restrictive driver xmfr.  Electronic Supply use to sell and may still have some real nice driver transformers that work real well.  The second thing is to take out those 500 pf coupling caps and put something a bit larger in.  Doing those 2 simple things will improve things quite a bit.  Of course you can do more but that gets more involved and you may not be interesting in doing that.  If you increase the coupling caps remember to beef up the caps B+ decoupling caps on the supply rail otherwise you may get some motor boating...

I remember years back an article was written in ER on some receiver mods.  If you find the receiver not living up to your expectations, you may find help in looking at that article.  

Marty, WB2FOU gave me the matching wooden speaker which looks great with the receiver.  

The Apache was my second rig right after my DX-60 back in 1967.  

Let me know if you need any parts for the rig.  I have bits and pieces of an old one around here.  

Enjoy....

Regards,
Joe, W3GMS        

[W3GMS]

John,
Our posts must of crossed in mid air concerning the ER articles!  Sorry for the repeat on that item.
Joe, W3GMS 

[Todd, KA1KAQ]

You did well, Gary. Especially if you got the chrome knob models. They have that '57 Chevy Bel Air look.

WA2PJP has done some fairly simple (compared to the ER articles) mods that really make the Mohawk work well as Johnny sez. Pretty amazing, actually. He spent a lot of time developing then and is going to document them at some point, then post them here for all to benefit from. Sounds like you're already well on the way.

Didn't see you at NEAR-Fest, did you skip this one?

[WQ9E]

Gary,

Just remember once you get a few of the Heathkit "Indian" series they start to multiply.

I think I have some Apache parts around also so let me know if you run into a need.

[WA2ROC]

Yep, you're really gonna like the "Injuns"

Here's mine.  I'll have to make room for that Warrior when one shows up

Oh, you'll have to excuse that "Hallicrafters" on top of my Mohawk.  That's waiting for am HT-37 to keep it company.

[W1AEX]

Gary,

Sounds like you scored a nice TX-1 and RX-1 station for an unbelievable price. That's a great looking collection by Dick and Rodger too. I never owned a TX-1, but I did use an RX-1 for a couple of years in my basement station. Whenever I pulled it out of the case to work on, it always made me smile to look at the amazingly convoluted collection of gears, levers, pulleys, and belts that were used between the front panel and the chassis. It looked like one set of engineers designed the front panel, another team of engineers designed the chassis, and a third engineering group designed all the linkage to make the front panel work with the chassis. The fact that in spite of the mechanical complexity it all worked so well and so reliably is something to ponder given the fact that today so much stuff is made of plastic and pseudo metallic construction.

Enjoy your new Indian station Gary!

73,

Rob W1AEX

[w5rkl]

Electric Radio had a very interesting article in December 1993 issue number 56, titled "THE TX-1 AND RX-1: HEATHKIT'S GREEN MACHINES" by Chuck Penson WA7ZZE. This article discussed the RX-1 and TX-1 production, the hiring and firing of engineers back then, and who did what during the production of both the RX-1 and TX-1. A very interesting article.

The RX-1 modifications by Thomas Bonomo, K6AD, were carried in Electric Radio in 3 separate articles.

Part one is in Electric Radio November 1997 issue number 103, starting on page 20.

Part two is in Electric Radio December 1997 issue number 104, starting on page 20.

The final part three is in Electric Radio January 1998 issue number 105, again starting on page 20.

Tom can provide a large modified schematic of the RX-1 that contains all of the changes from the three articles. I don't remember what I paid for the schematic but it wasn't much, maybe $15 plus postage. Drop Tom an e-mail and I'm sure he can give you the cost of reproducing the large schematic and postage. It's well worth the cost.

My TX-1 has Fran's, W3SCC, audio modifications. That modification really makes the TX-1 sound good. I performed the mod to a local ham's TX-1 and he couldn't believe how good his Apache sounded after the mod was completed. It takes a couple of hours or so to do but it's well worth it. Most of the parts may be found in your junk box. Most of the mod is rewiring the speech amplifier, removing the clipper (6AL5) and the small round filter, and adding a .001ufd 2KV disc cap across the secondary of the mod transformer. You can download the modification schematic at the following link:

http://www.amwindow.org/tech/htm/w3sccmods.htm

I haven't had my Apache on the air or powered up for about 3 years. I don't have room or a desk that can handle the 105 pounds. I also changed the final amplifier cooling fan by installing a 120VAC muffin fan. I had to change the amplifier cage top cover because the original cover, with the new muffin fan mounted to it, would not allow the Apache to slide back into the cabinet. I made a new cover out of perforated aluminum, cut to the size of the top, and mounted the fan to the new cover. The Apache now slides back into the cabinet and keeps the final much cooler than the original fan does. I think I still have the original top cover but not the original fan, the fan doesn't work anymore.

I would be interested in the audio driver transformer change. This appears to be a weak link the Apache audio chain. I have no made any of the Mohawk mods yet, other things have kept me from doing it. I did replace the final choke bypass capacitor because I could hear a "ticking" sound when the transmitter was keyed. The cap appeared to be shorting so before it blew I replaced it with a new 3KV cap from Mouser. Up until the last time I had it on the air, the cap was doing quite well. The HV filter caps need to be changed. I have a pair of tall CG (Computer Grade) 140ufd 450VDC caps I intend on using as replacements. I replaced the original caps 4 years ago with a set of identical caps I pulled from an SB-401 transmitter that looked new (the 401 transmitter had never been on the air. I still have the 401 and it works great). The internal leakage current was not perfect but it was below the maximum 4ma Sprague says for that value and voltage rated capacitor.

The ER back issues can be obtain from ER for a couple of bucks each plus shipping. Drop ER an e-mail and they can tell you the total cost.

73s
Mike

[WU2D]

Actually the HX-10 and the RX -1 are the pretty Indians...

Do you know that I missed the AWA convention this year and a Mohawk in "good" condition was auctioned for $10! I saw the auction results in this edition of the Journal.

Mike WU2D

[WZ1M]

Thanks for all the help guys. Todd, sorry, didnt make it to Deerfield this fall. Had other prioritys to attend to. A bit of brief history on me. Been hamming since 1960. Love to home brew and collect boatanchors. The hobby took over the house so I had to build another building just to store the stuff I have gathered over the years. Love to take basket cases and bring them back to life. Specialty are SP-600's. Done quit a few of these in the past. DX-100,s, NC-300's, GPR-90,s, R-390A,s and Hallicrafters. Have about 65 Hallicrafters in my collection. As for parts and tubes, not a problem. Last count on the tube inventory was up around 35,000 and more parts than you can imagine. This stuff just lands on my doorstep. For example, got a call this last monday evening on a couple of receivers for free if I wanted to pick them up. One is a national NC-270 and the other is a Collins R-392. Its a two hour ride but rest assured, I will have them come Saturday morning.
Regards,
Gary

[WA2ROC]

Some folks just seem to have all the luck, don't they?

As for me, the only time that people ask me if I want something, it's one step before the trash pile!

[N8UH]

Some folks just seem to have all the luck, don't they?

As for me, the only time that people ask me if I want something, it's one step before the trash pile!

Same here. I wish I had Gary's problems! Heck, with the lack of festers here, I'm having trouble just putting together a decent junk box!