The AM Forum
March 28, 2024, 08:51:35 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Reproduction Lettine VFO and Tuner  (Read 17910 times)
0 Members and 1 Guest are viewing this topic.
n4joy
Member

Offline Offline

Posts: 224



« on: March 17, 2019, 12:21:04 PM »

I am a collector of all things Lettine but have never been able to locate a Lettine VFO and tuner.  Only some pictures exist on LA5KI's website.  I decided to use schematics from Bama and scant photos to make my own.  Other than a Zener on the CT to drop B+ to 300V under load, I followed the schematic exactly.  

The VFO is based on a Clapp oscillator and uses a 5763, two OB2 VR tubes, and a 5Y3.  I used chassis punches and step bits for the hole punching.  The cabinets are Bud and were powder coated with "gun metal" wrinkle to duplicate the painted wrinkle finish.  After a 30 minute warm-up, drift is about 20hz per minute (Tung-Sol 5763).  I just used regular silver micas and the drift is okay for AM work.  Interestingly, the first 5763 tube I used (unknown manufacturer) provided a drift of almost 150hz per minute!  I didn't realize there could be such a difference between manufacturers!

Here are the photos of the original units and next are my finished products.  The cabinets are larger than they should be but these were on sale and CHEAP!


* 240vfo.jpg (44.17 KB, 565x382 - viewed 981 times.)

* 240tu.jpg (42.16 KB, 541x378 - viewed 1035 times.)

* 20190315_143718.jpg (350.39 KB, 2560x1440 - viewed 1144 times.)
Logged
n4joy
Member

Offline Offline

Posts: 224



« Reply #1 on: March 17, 2019, 12:22:17 PM »

Here are some moire photos of the construction.  I love step bits!


* 20190130_215041.jpg (148.66 KB, 873x1080 - viewed 1102 times.)

* 20190130_215051.jpg (158.03 KB, 873x1080 - viewed 1043 times.)

* 20190202_085112.jpg (128.95 KB, 873x1080 - viewed 945 times.)
Logged
n4joy
Member

Offline Offline

Posts: 224



« Reply #2 on: March 17, 2019, 12:25:56 PM »

And some more...  next project is to create labels, which will likely be the most difficult part of the project!


* 20190308_202902.jpg (845.52 KB, 2560x1440 - viewed 993 times.)

* 20190203_012026.jpg (729.29 KB, 2560x1440 - viewed 1068 times.)

* 20190203_175614.jpg (150.76 KB, 873x1080 - viewed 974 times.)
Logged
KA0HCP
Contributing
Member
*
Offline Offline

Posts: 1188



« Reply #3 on: March 18, 2019, 04:05:02 PM »

Very nice!   I was researching something last month in the early 50's and came across the Lettine ads again, renewing my curiosity.   For being advertised so prominently for several years, we don't hear much about them these days.
Logged

New callsign KA0HCP, ex-KB4QAA.  Relocated to Kansas in April 2019.
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.033 seconds with 18 queries.