Re: {Collins} S line zero-beat issue in Transceive Mode?



Would it not be simple enough to add trimmer caps across the BFO crystals in the transmitter? The mechanical,filters,are very correct in terms of passband position so the error in crystal frequency can only cause one or the other sideband to be incorrectly positioned anyway. I picked the transmitter, for this alteration since the effects old be less noticeable for,the user. By adding these trimmers, you would zero beat the TX and RX just the way you do when matching USB and LSB on the PTO.

Alternatively, one could ditch the notion of using the PTO offset for matching USB and LSB and use the TX keying line to pull the PTO's when going fro TX to RX. This would be quite easy to do.

Getting two new XTALs from INRAD is no guarantee these will operate on the same frequency anyway. Either of the simple alterations I just described will accomplish the feat perfectly.

Gary

Sent from my iPad

> On Nov 23, 2014, at 2:13 AM, David Harmon <k6xyz@xxxxxxxxxxxxx> wrote:
> 
> There is no alignment procedure to make the S-Line transceive on the same
> frequency.
> 
> On frequency transceive operation is determined by the BFO xtals in each
> unit.
> Your tx xtal may be low or your rx xtal may be high in frequency.
> Real world experience says that both xtals will be off spec frequency.
> 
> To transceive on the same frequency on LSB.....the LSB xtals in the tx and
> rx must be on the same frequency....not necessarily on the correct
> freq....just the same freq.
> Same thing for USB.
> To fix this problem you must replace the BFO xtals in each unit.....either
> LSB or USB....or both....2 xtals or 4 xtals.
> Not very hard to do....but it is the weak spot in the S-Line.
> For now you can operate split and use the SYNC function on the tx to get
> exactly on frequency.
> You can order the xtals from INRAD.
> http://www.inrad.net/home.php?cat=103
> 
> 
> 73
> 
> David Harmon
> K6XYZ
> Sperry, OK
> 
> -----Original Message-----
> From: Collins [mailto:collins-bounces+k6xyz=sbcglobal.net@xxxxxxxxxxxxx] On
> Behalf Of Rich Hallman - N7TR
> Sent: Saturday, November 22, 2014 11:34 PM
> To: collins@xxxxxxxxxxxxx
> Subject: {Collins} S line zero-beat issue in Transceive Mode?
> 
> When I have one of my S line's (75s3c and 32s3) in tranceive and on
> SSB.....Stations who are calling me back after a CQ are low in frequency by
> about a half Khz.    I've looked around but haven't found how to align the
> two radios so they are on the same frequency when in trancieve.  I am using
> new RG58C/U interconnect cables from RF Connection.  I also tried the
> original cables and have the same problem.  So I think I eliminated the
> Interconnect cables from being the problem.
> 
> Any thoughts?
> 
> Thanks...
> Rich
> 
> Rich N7TR
> ex KI3V, N3AMK, WB3JOV
> www.n7tr.com<http://www.n7tr.com>
> http://www.qrz.com/db/N7TR
> Telnet: dxc.n7tr.com N7TR DXCluster
> 
> 
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