[R-390] R-390 and CV-157 timeframe

[William J. Neill]

Well, keep in mind that the CV-116( ) also had the same AFC ckt.  I  
have three of 'em running dual-diversity with an R-389, R-390s,  
R-390As, one R-391, and one 51J4 (had to realign one side of a CV-116 
( ) IF input for that sucker) and the AFC does good work as needed  
because there is some drift of the carrier because of (I presume)  
changes in the ionosphere.  Years ago, I could run more or less solid  
copy for 24 contus hrs or more but no longer have such opportunities  
because of the dearth of HF RTTY tfc.

Bill Neill
Conroe, Texas

On May 20, 2008, at 8:03 AM, Sheldon Daitch wrote:

> This brings us an interesting change in focus in the R-390
> series and its relationship to the CV-157 convertors.
>
> The CV-157 has an AFC circuit, so, if an R-390 and a
> CV-157 are teamed together, the absolute frequency drift
> of the PTO in the receiver wasn't that important as long as
> the total system drift, to include transmitter frequency
> change, receiver PTO change and even the minor change in
> the CV-157 tuning system, as long as that drift did not
> exceed the range of the mechanical AFC variable capacitor.
>
> So, I suppose the question might be, what is the relationship
> between the fielding of the R-390 and then the CV-157?
>
> Don't misunderstand that I am trying to put down the
> stability of the R-390 series and the PTOs in general, but
> someone in systems design recognized a need for the AFC
> circuit in the CV-157.  Was the AFC added because of the
> higher frequency stability requirements of multiple channel
> RTTY circuits on a VF channel, due to even minor drift by
> the PTOs or the frequency stability requirements even exceeded
> the good specs on the R-390s?
>
> 73
> Sheldon
> WA4MZZ
>>
>> Another thought about T comp needs is that it's my understanding  
>> that many of these receivers were used for RTTY and temp  
>> performance may have been driven totally by those requirements.   
>> Basic PTO temp performance AND the oven may have been needed for  
>> long term "set and forget" tuning stability.
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