[R-390] Please spare us

[John Kolb]

The 51J-4/R-388A has the same crystal filter and phasing control as the 
51J-3 as well as
mechanical filters. The change was made by removing one of the stages of 
IF amp and
replacing it with a module containing the filter switching, filter 
sockets, and two IF amp tubes.
This module was also sold seperately to convert 51J-3's to 51J-4's.

The modules show up occasionally on ebay.

John

Kenneth Arthur Crips wrote:

>The R388/URR (51J3) has crystal filtering, and the R388A/URR (51J4) has 
>mechanical filters. I have never had the opportunity to compare these two 
>radios side by side. If anyone has been able to do this how do the two radio 
>compare.  My SP-600 has both kinds of filters but it needs a serious 
>tune-up, it is real deaf so it just isn't possible to compare using it. I 
>must say I like the phasing control the crystal filtering has.
>
>                                Ken
>  
>