[TenTec] RF Speech Processor "TX IMD"

Tue Jun 18 16:07:09 EDT 2013

Kim, I think the bandpass filter comment was targeted at what I said
earlier.
You mixed up my points.  I said it would not help to have a BPF on the good
transceiver (receiving) but probably would on the bad transceiver
(transmitting), though we did not try it because we just threw the bad ones
out.  Lots of them.

Yes, of course a BPF will help.  The current cost of a set of BPF's for the
classical ham bands (but not the WARC bands) is $800 - more than some of
these transceivers cost.  I maintain the OEMs could fix the cause of the
problem for a lot less than $800.

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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