Heathkit Mohawk Improvements – by Thomas Bonomo K6AD

Heathkit-Mohawk-Chrs-Article-Main-PhotoThe first ham radio station I saw as a kid was the Heathkit Mohawk RX-1 receiver with the matching Apache transmitter.  Those big green high-tech boxes sure made an impression! So, when I spotted a good cosmetic-condition Mohawk to complement my Marauder transmitter, I jumped at the opportunity.

The Mohawk, which was introduced as a kit in 1958, was Heath’s first ham band-only receiver, and was the first Heathkit to sport the now-famous “Heathkit green” colors. This receiver offers a number of interesting features. Heath separated the usual single knob RF gain control found on most receivers into two controls, an RF Gain and an IF Gain control. The ability to control the gain of the front-end stage separately makes it possible to reduce cross modulation from extremely strong signals, while maintaining good receiver sensitivity. The Mohawk also had a selectivity switch control allowing bandwidths of 5, 3, 2, 1 and .5 KHz.

I devoted many days to the restoration of my Mohawk. The results, however, disappointed me, so I took to the forums. The views of other owners ran along these lines:  “What a junky receiver . . . ..”   “Terrible AGC . . .”  “Worst audio of any receiver I own.”   “Product detector really distorts.”   “Drifts too much to keep up with.”

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                          Download Complete Schematic

Note:  If the schematic won’t render in your browser’s PDF viewer, use “Save Link As” and save to a folder on your computer.

This Post Has 23 Comments

  1. Tom, can you send me the latest rx-1 schematic, modified? Why would someone add a resistor 850
    Ohms in the ct of the power transformer? Do you know who made replacement power transformers
    For the rx-1?

    1. Mark i dont know if your still looking for a Mohawk but there’s a guy here in Indianapolis,In N & L Distributors ( 317-787-2545 Harold ) he has the Mohawk and a Apache they both look pretty nice you can google his shop and there is a picture of them i just seen your post and figured I’d let you know

  2. I would like to have a copy of the schematic. I just got a Mohawk that seems to have some modifications and will compare to manual to identify any changes. But I have also experienced some of the problems you indicated and enjoyed the article. The link on the download for the schematic fails to load. Thanks for the article.

  3. I have two Mohawks and I am in the process of modifying one now. Once I have one up I will modify the other one using one with the Marauder the other one is used with the SB10 and the Apache would greatly appreciate a copy of the PDF Schematic if it is still available. thanks.
    Respectfully
    BoB Benson W6VVA

  4. – Scott KD8FXF –

    Hi Tom,
    I just found and read your article on the improvement modifications for the Heathkit RX-1 Mohawk. I attempted to download the schematic .pdf from your posted link and also by “saving link as” but neither worked. Could you email me that modification schematic .pdf ? Thank you so much.
    I do have a large collection of fine Heathkits, along with a Collins station, plus many more radios and equipment. I am partial to Heathkits and tube radios. I have an Apache TX-1, Mohawk RX-1, Marauder HX-10, and (3) Warrior HA-10 amps. Why three? I originally purchased one. Years later, my very close friend, Tom Nickisch, W8AMZ (SK), famous for his W8AMZ Antennas, passed away at 49 years old on December 18, 2013 from medical problems. Tom was a Heathkit enthusiast, and a wealth of information on Heathkits. He always stoked my interest in Heathkit radios and equipment. He had a Warrior HA-10 amp in very nice condition. I really didn’t need it, but I wanted to have something to remember Tom, so I purchased it from his XYL. Several years later, I acquired a bunch of Heathkit equipment from the estate of a local Silent Key, and included was a really nice HA-10 Warrior.
    Montague, Michigan is a very small and quiet town located in western Michigan. It’s about 20 miles north of the city of Muskegon. I live on 10+ acres of mostly woods, but have a large field behind the house. Montague is on White Lake, and inland lake, seven miles long, and connected to Lake Michigan via a navigable channel. White lake is 2 miles form my house. Lake Michigan is 3+ miles from my house. People ask me where I go on vacation. I tell them I live in a vacation land. Visitors come here from other cities and states to go on vacation.
    I do belong to a local Amateur radio club; M.A.A.R.C. (Muskegon Area Amateur Radio Council). It’s on 4+acres of wooded land, across the road from Lake Michigan. The club’s call sign is W8ZHO. The club property was donated by a Muskegon electronics/radio businessman in 1941. He was Chuck Schecter, W8UCG (SK). Before the club had the property and a clubhouse, the Muskegon County area radio operators would gather at one of the Ham’s personal radio shacks. In 1941, members got together, cleared land for the clubhouse, and poured the foundation for the clubhouse. But then, the U.S. entered WWII, and the building of the clubhouse was suspended. Many members went into the military. The Federal Government mandated that any and all amateur radio transmissions would cease during the duration of the war. After the war ended, the members got back together to finish the building of the clubhouse. Since then, it has been expanded and improved. We have a radio room, a kitchen, a restroom, and a large multi-purpose great room with a fireplace. We have a 110 foot tower supporting a large yagi HF antenna, plus 2 meter yagi, and different band wire antennas. A second 60 foot tower is due to come down and be replaced by a heavy duty 70 foot motor cranked up tower. We hold many social and radio events at the club, but due to this year’s COVID-19 restrictions, most of the activities have been suspended.
    The clubhouse is a 12 mile drive from my house, as I have to drive around White Lake, and then down the Lake Michigan coastline.
    Thank you for the article on the RX-1 Mohawk receiver.
    73,
    – Scott KD8FXF –

    1. Glad you enjoyed the article. The Mohawk is a great period radio, that once modified will give you decent performance for the vintage. Your club sounds like fun. I’ll forward the PDF of the schematic.

      Tom K6AD

  5. Hi Tom,

    I just came upon your article in preparation of restoring my Mohawk. Great in-depth work and I will use it restoring mine.

    I too cannot download the schematic. Could I trouble you to send one over my email address?

    Regards,
    Alan, WB2FZC

  6. gud morning! just stumbled on your website and I have to say thanks! I am getting the itch to repair /reserect tube type radios. i have an old sx 110 that is going to be my first attemp.
    also for equip i have a hickok 209 vtvm signal gen freq counter and o-scope I hope the weakest link is in the void above my eyebrows and between my ears! what do you suggest for more equip? thanks 73 dan wa0nxe@gmail.com

    1. Glad you got the mods working. For your Apache, I’d suggest you get a manual and follow the instructions. Reproducing those here would be too long and take too much time.

      Tom

      1. Hello. I found this site while looking for information on restoring an SX-28A, but saw that you also perhaps have schematics for modifications for the Mohawk RX-1. I have the TX-1/RX-1/SB-10/HX-10 line, and have been very disappointed in the performance of the RX-1. Would you mind e-mailing me the mod info as well? Thanks. WA0RVK

  7. I’m 74, radio listener,would like a Heathkit mohawk restored receiver,or hammarlund hq 120. Restored means usually in good working
    condition.

    I may try for an amateur license this fall,do you know anyone
    that has either of these two radios in restored condition?

    Please answer by email,I live in Escanaba,Mich,49829

  8. Hi, great article on the Mohawk….have one that’s a perfect candidate for these mods/ improvements. Can you email me the schematic? thanks, W9TNJ

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