Rebuilding Heathkit sb-401 - Page 1
Forum section: electronics / projects

author: SlashBuster
author_rank: Newbie
timestamp: January 22, 2015, 08:16:18 pm
content: Hi,I have a problem. I want to rebuild the heathkit sb-401 with an digital frequency counter. But there are some crystals which does not exist anymore or they are way to expensive. Any ideas how to solve this or replace them with something else?Thank you in advance

author: Kalvin
author_rank: Super Contributor
timestamp: January 22, 2015, 08:36:03 pm
content: Entering "Heathkit sb-401 crystals" into Google will show some nice results.However, if you want to replace the crystals with something modern, a simple DDS (direct digital synthesis) sine-wave generator might be a good choice. Those modules cost typically around $10 - $20.

author: free_electron
author_rank: Super Contributor
timestamp: January 22, 2015, 08:42:45 pm
content: there is mutiple options- change jobs so you make more money so you can afford the expensive ones- cut your own- find such a heathkit receiver and strip it for parts- buy a few cheap programmable oscillator chips for silabs or epson and set them to the frequency you need.- dithc this old 'nostalgic'crufty designaltogether and build something more modern that uses pll tuning

author: Radio Tech
author_rank: Frequent Contributor
timestamp: January 22, 2015, 10:42:46 pm
content: As Kalvin said the DDS would be your best route to go.I was working on a few older units myself.But I do have to warn you, judging by you post on this it may be too big of a task for you to handle. Especially not knowing your experience in electronics and old rigs like the 401.This is not a plug and play modification.QuoteUnder normal conditions I would disagree since I love nostalgic radios myself. but I must agree with free_electron not knowing your skill level. I always encourage folks to learn and repair their own rigs.Perhaps it would be better to find a buyer for the 401 and purchase a more modern rig that fits your needs

author: SlashBuster
author_rank: Newbie
timestamp: January 22, 2015, 10:53:22 pm
content: Thank you for your anwser. So I am a Ham. And I know how these circuit work but I always like to hear the opinions from others, maybe someone haves an idea I never would thought of. I think the dds is a good option. You can get the kits cheap from ebay. But I have to try it. The reason I want to rebuild this, is that it was the best transmitter from heathkit and here in Germany you can't get them. And there are only a few SSB transmitters that work well.Thank you very much73's from DO1KBB

author: Radio Tech
author_rank: Frequent Contributor
timestamp: January 23, 2015, 12:31:09 am
content: Quote from: SlashBuster on January 22, 2015, 10:53:22 pmWell that changes everything. DDS is the way to go. I use a small board that contains a pic chip with a DDS board piggy backed on it.

author: German_EE
author_rank: Super Contributor
timestamp: January 23, 2015, 10:58:54 am
content: Try Quartslab for your crystals, I have used them before. (Note, the spelling is correct here).

author: Mr Simpleton
author_rank: Unknown
timestamp: January 23, 2015, 11:46:42 am
content: If you are restoring the old transmitter you should really try to find crystals! There are offerings on Ebay and such for a reasonable amount.... Apparently they left them out, as the transmitter was supposed to be used with the SB-301 receiver.I would NOT use a DDS here, far too much spurs. If replacing the crystals with something modern, why not a Si-570 and a one-chip processor. Great performance! Just make sure you do have the correct output voltage, usually high impedance and high voltages due to tubes.Good Luck and have fun with your old Heathkit transmitter !!

author: SlashBuster
author_rank: Newbie
timestamp: January 23, 2015, 01:06:42 pm
content: How expensive are these crystals from quartslab?