[Hallicrafters] SX-28A 1st RF tube replacement

[Roy Morgan]

On Apr 3, 2009, at 9:15 PM, Chuck McGregor wrote:

> Roy Morgan wrote:
>> On Apr 3, 2009, at 8:31 PM, Carl wrote:
>>> Thats the W6SAI 6SB7Y article you may be referencing Roy??
>
> The "Orr Article" was in CQ, November 1957. I just uploaded it to
> Mediafire:   http://www.mediafire.com/?mvltjjzyzyn

For the record, the article mentioned is:

New Life for the National NC-240D
William I. Orr, W6SAI
November 1957, CQ
Page 103-105 and Pg 164

In summary, the article advises the following modifications, and gives  
full details for circuit and component changes:

- Change the RF amplifier tube from 6SK7 to 6SG7
- Change the mixer from 6K8 to 6SB7-Y  (The Y indicates the low loss  
base version of the tube)
- Replacing many or all 0.1 uF paper capacitors
- Complete a re-alignment according to the manual
- Cleaning the finger contacts to the sliding coil catacomb
- Adding a VR-150 regulator tube to supply the HF oscillator
- Possible use of an external SSB IF adapter

Roy

Roy Morgan
k1lky at earthlink.net
529 Cobb St.
Groton NY, 13073