Message-ID: <001801bf1432$b421d660$0600a8c0@main>
From: "Dave" <dave@picks.force9.co.uk>
To: rsgb_lf_group@blacksheep.org
References: <1999100310233468199@zetnet.co.uk> <38023DD1.B30@xtra.co.nz>
Subject: LF: Re: TS 850
Date: Mon, 11 Oct 1999 22:44:48 +0100
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Bob,

> I have had a "play" with a TS 850SAT, as a try before buy offer.  I can
> confirm it works better than I would have thought on receiving LF.  The
> circuit diagram shows it has a separate pre-amp for tuning below 500
> kHz.  While it tunes down to 30 kHz, the sensitivity is fairly dreadful
> down there, so there must be a lot of roll-off below 100 kHz.  We do not
> have access to a 76 kHz band down this way.  I have asked our regulatory
> authority to be able to use the CEPT band at 136 kHz.  Our current
> access is to 165 - 190 kHz.  But whatever, the TS 850 can technically
> tune all.

I find it very good on LF, especially with two CW filters fitted!
>
> I was also impressed by the TS 850 NB1 noise blanker, as we have a hash
> problem in Wellington.  NB2 is specifically for the now defunct
> woodpecker, and did not do much good for spike suppression (but may be
> able to be redesigned for general use?)

Noise blanker doesn't seem to work much with the narrow filters in, but it
depends on the character of your noise!
>
> Unfortunately I found the sensitivity of the receiver on HF to be around
> 20 dB below spec.  Also the 12 dB attenuator appears to be "open
> circuit" when selected.  I can hear the relay clicking, so the series
> resistor in the L pad seems to be open?  So I suspect it has had an
> inadvertent squirt of RF in the front end, while the HF rather than LF
> pre-amp was selected.  As it meets spec on LF, it shows that there is
> not too much to be fearful of?  It goes back to the vendor for a "covers
> off inspection" on Wednesday evening.

Yes indeed, probably a diode in the switching on the RF filter board. I
fixed a similar fault on a friend's rig.
>
> I am still at a bit of a loss to see why Mr Kenwood would provide such a
> good spec for below 500 kHz, as it has resulted in extra circuitry and
> obviously meant a higher cost of design and manufacture.  I'm not
> complaining!
>
The 450 is just as sensitive. Same front end.

> Should the HF receiving problem be resolved, I am likely to purchase the
> TS 850 SAT, and I would then look for a way to transmit on LF.  I
> currently do this with my Icom IC-735, by making it all band transmit
> (snipping the appropriate diodes) and adding a suitable low pass filter
> (inductor input T, to be hi Z to all HF) to the Tx mixer to tap off the
> LF Tx signal.
>
> The particular TS 850 also has transmit windowing in the 3 lowest bands
> (160, 80 and 40 metres) and gives less coverage than my licence allows.
> It also seems to clamp the output power to 50 watts on 160 metres.  If I
> buy it, I will need to also find out about "band plan" diodes or
> whatever they use, but all that may be overtaken by events if I opt for
> "all band transmit".

If you get it, I have all the info on the thing.

73, Dave G3YXM.