[Elecraft] Combo pre-amp

[Jack Smith]

I have a new design Norton preamplifier that might be useful for this 
purpose.

It has 11 dB gain through 30 MHz and 9 dB at 54 MHz, noise figure is in 
the 2.5-3 dB range, OIP2 > +85 dBm, OIP3 > +42 dBm. The OIP values are 
conservative numbers.

When power is switched off, the preamp is bypassed.

Housed in a custom built, powder coated, silk screened enclosure.

Power requirements, 13.6V @ 100 mA.

Model no. Z10043S.

Anyone interested in one can contact me off-list for a data sheet, 
pricing and delivery schedule. This preamp is not shown at my web site - 
too new to have a page yet.

Jack K8ZOA

On 5/26/2013 6:21 AM, Gary Gregory wrote:
> Hi ian,
>
> Gee thanks for the insight to your attempts on an internal pre-amp.
>
> I imagine that the lack of sensitivity on 12/15M has appeared after
> production also so again the position would be the same from Elecraft.
>
> It is a pity that to correct this can only be remedied with an external
> device. If they ever produce a remote 10/12M preamp that could be sat a
> foot or so away from the K3 this would help in my case but may not suit
> home stations and others. I realise I am most likely in a small minority
> here and I accept that without reservations.
>
> I would rather pay for what I need rather than a combo including 6M which
> is of no use to me.
>
> 73
>
> Gary
>
> On 26 May 2013 19:39, Ian White <gm3sek at ifwtech.co.uk> wrote:
>
>> Joe, Gary and Joe again:
>>
>>>>> I agree that an internal preamp (or premps) would be ideal.
>> However,
>>>>> in addition to the preamp(s) Elecraft would need to provide
>> *another*
>>>>> design for the KXV3A - one that switches the RX ANT IN/OUT
>>>>> connections to internal jacks - as neither the original KXV3 or
>>>>> current KXV3A have that capability.
>>>>>
>>>> let's not let that technical inconvenience reduce in any
>>>> way my hope for a cure to my sometimes demented desires....:-)
>>> I'm not saying it isn't possible ... takes one additional relay and two
>>> connectors.  There are even couple unused control lines on the KXV3A
>> that
>>> could be used to control the added relay and switch bands (10/12 and 6
>> M)
>>> if necessary.
>>>
>> Been there, tried that.  I tried two different ways to retrofit an
>> internal preamp for 6m, and neither of them worked well enough to keep.
>>
>> The problem is that any modification has to work within the very tight
>> space behind the rear panel of the KXV3 module. There is >>barely<<
>> enough space to install a tiny PC board behind the RX ANT IN and RX ANT
>> OUT connectors, with very tight limits on what can be included on that
>> board. The track layouts had to be designed with a step size of 0.025in
>> and in some places the tolerances were even tighter than that.
>>
>> Board #1 used a single subminiature DPDT relay and included a very
>> simple wideband preamp; but the single relay gave insufficient isolation
>> to prevent the preamp from oscillating out-of-band. There wasn't enough
>> space on the board for two relays, tuned circuits or any additional
>> shielding and decoupling; and it was impossible to make any further
>> tweaks without completely extracting the KXV3 module. Board #2 was
>> simpler, this time with two DPDT relays for improved port-to-port
>> isolation, and with two coax fly-leads that were long enough to reach
>> into the space above the KRX3 module (which Elecraft had reserved for
>> the 144MHz transverter). That allowed me to use a fully shielded 6m
>> preamp which gave a dramatic improvement in sensitivity - but now the
>> VFO encoder noise made it impossible to tune the band! I believe that
>> new problem was due to the use of two different grounding points, at the
>> KXV3 and on the top cover of the KRX3, and I couldn't see any way around
>> that.
>>
>> At that point I gave up on the idea of retrofitting an internal 6m
>> preamp. Elecraft could have included it at the initial design stage, of
>> course; but if my reading of history is correct, the demand for greater
>> sensitivity on 6m came >>after<< the K3 had been launched on the market.
>> By that time the internal hardware design was already locked down, so I
>> can fully understand why Elecraft were obliged to produce the PR6 as an
>> external add-on.
>>
>> Wayne has acknowledged that the K3 can sometimes be lacking in
>> sensitivity on 6m, and has stated that the external PR6 module is
>> Elecraft's solution.  I wouldn't expect that position to change
>> significantly.
>>
>>
>> 73 from Ian GM3SEK
>>
>>
>>
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