[TenTec] RF Speech Processor "TX IMD"

Fri Jun 21 02:55:50 EDT 2013

Kim, you may have just come up with a great concept for planning a contest
radio station.
"Always live south of your competitors".
It's the same over here too, we almost never point the beam south.
You work an occasional multi to the south, but then you point the beam back
to the NE or NW where the action is.

73
Rick, DJ0IP

-----Original Message-----
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Kim Elmore
Sent: Friday, June 21, 2013 5:19 AM
To: Rick - DJ0IP / NJ0IP
Cc: 'Discussion of Ten-Tec Equipment'
Subject: Re: [TenTec] RF Speech Processor "TX IMD"

Sorry for the delayed response.

Yep, I misunderstood: no amount of filtering on a rx will fix a poor tx. 
Nothing can be done about transmitted phase noise or poor IMD of a tx once
it leaves the tx.

I was reminiscing about K0RF back in the late 80's/early 90's when he was
running a TS-930S. That was about as good as anything got back then. 
We certainly have much better, now. He has truly fantastic antenna array and
full QRO Alpha amps (or did back then) and when he was pointed at me, about
10 mi south, all I could do was switch bands. Fortunately, he wasn't
compelled to do that very often in a contest simply because a lot of mults
are in other directions.

Kim N5OP

On 6/18/2013 3:12 PM, Rick - DJ0IP / NJ0IP wrote:
> Reply No. 2 on this, Kim...
>
> I thought K0RF was now running an FT-5000 in class A mode, driving a 
> very good linear.
> As such, I assume you are speaking historically.
> You shouldn't have any problems with him anymore.
>
> 73
> Rick, DJ0IP
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of 
> Kimberly Elmore
> Sent: Tuesday, June 18, 2013 6:27 PM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] RF Speech Processor "TX IMD"
>
> Yes, indeed: the introduction the PLL lead to wonderful flexibility in 
> frequency coverage and generation along with mounds of phase noise. 
> The phase noise has been largely corralled, but not IMD. I wonder: 
> what IMD level is good enough? Something around -40 dB seems considered
insufficient.
> Would -50 dB do it? -60 dB? What things affect the linearity and 
> transfer function of a PA? Can IMD be "designed out" of a PA, or is it 
> fundamentally caused by the transfer function inherent in the active, 
> amplifying device (transistor or tube) itself? I honestly don't know.
>
> Oh, and when I heard K0RF's phase noise, I was about 10 mi from him :)
>
> I will take issue with one aspect, though: band pass filters on the 
> output of a transmitter can most certainly attenuate phase noise, or 
> any other emitted RF, that falls outside the filter's pass band. Phase 
> noise is Gaussian (white) in nature and we can turn white noise into 
> anything we want with proper filtering. There's nothing special about 
> phase noise or nth-order IMD products in this regard: band pass 
> filters pass only what's in the pass band (the ultimately tautology!). 
> The pass band may be, say, the entire 20 m band plus a bit for safety, 
> but a good filter will stop anything outside of the pass band. So, a 
> transmitter with a good band pass filter on it won;t much affect any other
band but 20 m.
>
> I'll take my '930S out again this year and double check its noise 
> generation as I know darn good and well that it makes some. I'll even 
> try it on 'phone to see how much trash it makes because I really don't 
> have any idea right now. No, I don't don't own the proper equipment, 
> such as a spectrum analyzer, to allow me to measure it. I suppose that 
> makes me an inadequate ham in some eyes (hangs head in shame).
>
> Kim N5OP
>
>
> ________________________________
>   From: Rick - DJ0IP / NJ0IP <Rick at DJ0IP.de>
> To: 'Discussion of Ten-Tec Equipment' <tentec at contesting.com>
> Sent: Tuesday, June 18, 2013 10:03 AM
> Subject: Re: [TenTec] RF Speech Processor "TX IMD"
>   
>
> Guys, this is EXACTLY what I have been talking about.
>
> BROADBAND PHASE NOISE - not just the 3rd order IMD.
> This noise is not just wide, it's across the entire spectrum.
>
> Now hang a 1.5KW linear amp on one of those!
> You don't just bother others on your block, you bother those within a 
> couple of miles.
>
> But of course some of the rigs are also pathetic on the higher order IMD.
> NONE are as good as a 1960s Collins 30S-3.
>
> (OK, sure the FT-5000 is if you run it at 75w in class A, but as soon 
> as you turn on the speech processor, it's hosed too!)
>
> Nearly 50 years, not only have we seen no progress, the IMD has gotten 
> worse.
>
> 73
> Rick, DJ0IP
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Duane 
> Calvin
> Sent: Tuesday, June 18, 2013 4:49 PM
> To: 'Discussion of Ten-Tec Equipment'
> Subject: Re: [TenTec] RF Speech Processor "TX IMD"
>
> Same with the TS-430.  I have a neighbor less than 500' away running 
> CW all the time.  When he had his TS-430 he covered a major portion of 
> the band he was on with transmitted phase noise.  It was a pure 
> delight when he up graded to a TS-570 a few years ago and then I 
> couldn't hear him until I was within 5-10 KHz of him or so.
>
>       73, Duane
>
> Duane Calvin, AC5AA
> Austin, Texas
> www.ac5aa.com
>
>
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Barry 
> N1EU
> Sent: Tuesday, June 18, 2013 9:41 AM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] RF Speech Processor "TX IMD"
>
> On Tue, Jun 18, 2013 at 1:16 AM, Kim Elmore
<cw_de_n5op at sbcglobal.net>wrote:
>
>> All that said, I never tried phone with it at FD but I'll give it a 
>> shot this year as a quick test to see if the IMD wipes out everyone else.
>>
>>
> We use a TS930S on ssb every year at Field Day and it just wipes out 
> the rig that's down in the cw portion of the same band due to phase noise.
>
> Barry N1EU
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