But that was yesterday.
What do people do today?
I'm not a fan of RF sensing. Hot switching? No thanks.
You may get away with it in SSB but not in CW.
73 - Rick, DJ0IP
(Nr. Frankfurt, Germany)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Gary J
FollettDukes HiFi
Sent: Tuesday, September 13, 2016 3:07 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Scads of used Icom IC-7300
Several preselectors were produced by commercial vendors, some time ago, not
likely as good a preselector as yours, but they offered RF sensing to pass the
TX signal around the preselector.
This seems to be a better solution than modifying the radio.
For those not comfortable with RF sense switching, one might consider using the
PTT line to switch around the preselector.
With most TT radios, these lines are very fast (for QSK) and could be in
parallel with the linear key line if a linear is used.
‘Gary
> On Sep 13, 2016, at 5:55 AM, rick@dj0ip.de <Rick@DJ0IP.de> wrote:
>
> Correct, my pre-selector is RX only, which the name implies.
> That is why every transceiver I have had since the mid 70's was
> immediately modified with two RCA phono jacks mounted on the back. I
> interrupt the RX ANT line internally and run it thru the two jacks,
> jumpered of course when no preselector is attached. Even my Eagle has
> this mod. The OM7 had it available but very few people performed the
> mod. I did it on the OM7 I tested here prior to its announcement and
> it made a WORLD of difference on 40m.
>
> 73 - Rick, DJ0IP
> (Nr. Frankfurt, Germany)
>
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of
> shristov
> Sent: Tuesday, September 13, 2016 10:15 AM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] Scads of used Icom IC-7300
>
> "rick@dj0ip.de" <Rick@DJ0IP.de> wrote:
>
>> However the Dunestar SPECS on their web site claim 40dB band-to-band
>> rejection. I was just quoting the specs.
>> http://www.dunestar.com/store/Single-Band-Bandpass-Filters-pid-4.html
>
>
> Hi Rick,
>
>
> that's what I had in mind.
> Taking the 7 MHz filter as an example, there is 40 dB attenuation on
> ~3.5 MHz.
>
> But on 6 MHz the attenuation is practically nil.
>
> Your preselector is the right tool for the job.
> But it's receive-only, given the 7.5 dB passband attenuation.
>
> Dunestar etc filters must have a much wider passband in order to
> achieve low enough passband attenuation, making them suitable for
> transmitting.
>
>
> Best 73,
>
> Sinisa YT1NT, VE3EA
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