[TenTec] RF Speech Processor "TX IMD"

Thu Jun 20 23:19:03 EDT 2013

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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