[R-390] IF sweep alignment

[rbethman]

I'd suggest re-looking at the circuitry!

Z-501 is NOT a crystal filter whatsoever!  For personal edification and 
amazement - it happens to be THE 455Kc Oscillator!

The only crystal that has EVER been on/in the IF deck.

I have NO idea how you intend to "sweep align" a circuit that you 
apparently do NOT know or understand.  That "can" is the HEART of the 
455kc IF!  Take it away, and there is NO 455Kc.

N0DGN

On 2/26/2011 7:47 PM, KA9EGW wrote:
> I beg to differ; reference Y2K manual, release 3, section 3.2.9.1 et al.
>
> On the 390 non-A, ref TM11-856, Section 59, on page 53.
>
> In both receivers it's Z501.
>
> Granted, the neither 390 non-A nor 390A has crystal lattice filters, but
> Z501 is what it is...
>
> 73, Brian KA9EGW
>
> -----Original Message-----
> From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
> On Behalf Of rbethman
> Sent: Saturday, February 26, 2011 5:59 PM
> To: r-390 at mailman.qth.net
> Subject: Re: [R-390] IF sweep alignment
>
> The R-390 series has NO crystal filters at all.  The R-390s used pure
> circuitry to achieve the end, while the R-390As use the mechanical filters.
>
> Bob - N0DGN
>
> On 2/26/2011 6:43 PM, Bill Hawkins wrote:
>> Haven't seen any mention in this thread of the mechanical filters in
>> the A version.
>>
>> You may recall that there was a hybrid combination of the A and a
>> non-A IF deck (R-725) because the mechanical filters prevented fine
>> direction-finding operation. Ringing mechanical filters, IIRC.
>>
>> There was also at least one thread in the good old days of this list
>> that strongly advised against trying sweep alignment of the IF strip,
>> because the ringing filters distorted the wave form.
>>
>> Perhaps you could use a wide band 455 KC receiver before the filters
>> to see the response curve of the IF transformers before the filters.
>> You can't align the filters anyway. What you do is find the center of
>> the 100 Hz filter (does an A have that crystal
>> filter?) and use that as the base frequency of the sweep generator.
>>
>> Hope this stirs someone's memory.
>>
>> Bill Hawkins