[Elecraft] KPA-100, etc.

[Phil Wheeler]

George Winship wrote:

>Wayne, Eric, Gary,?,
>
>I own K2-2217. Purchased the KPA-100, KAT-100-1, and KAF-2 last
>October before the price increase. Have not built any of these yet,
>but pulled out the KPA-100 yesterday and hope to get some done this
>weekend.
>
>Noticed that the 10m BPF mod and VFO alc mod are included. Would
>probably be a good idea to do the BFO mod and the PLL mod also, don't
>you think? Wondering about the mod to change the crystals to a matched
>set. I get good audio reports on SSB, but the receive audio sounds a
>bit compressed or tinney to me. Would this mod help?  The only mod
>that I have done to this radio is the 2nd xfil mod which helped some.
>Suggestions on these or others? My ops are about half and half between
>cw and ssb.
>

The BFO and PLL thermistor stability mod are  good.  Running the KPA100 
will make temperature stability  more important.

With S/N 2217, I'm not sure whether you need the matched xtal mod.  At 
some point the xtals in the kits became matched as well as they are now. 
 I just don't know when S/N-wise.  Ah .. here is a posting from Eric:

> +++++++++++++++++++++
> Date: Mon, 28 Oct 2002 14:38:52 -0800
> From: Eric Swartz WA6HHQ - Elecraft <eric at elecraft.com>
> Organization: Elecraft
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] New Crystals or Not
>
> As a follow on to my earlier email, we have been shipping the latest 
> CW and
> SSB filter crystals since about March 19th, 2002. Approximately from K2
> serial number 2570 on.
>
> 73, Eric
> =========
> Date: Mon, 28 Oct 2002 15:27:35 -0800
> From: Eric Swartz WA6HHQ - Elecraft <eric at elecraft.com>
> Organization: Elecraft
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] New Crystals or Not
>
> Some more clarification:  
>
> Over the lifetime of the K2 we have made several incremental 
> improvements to
> our filter crystal matching. When we went to a tighter crystal motional
> inductance (Lm) specification around 3/29/02, we first received crystals
> sorted at the vendor with with the older 4.91-20 label, as opposed to the
> 4.91-0195 that we were using just previously. We then had them custom
> labeled as 4.9136-S on subsequent shipments to us from the vendor.
>
> Here is the breakdown of K2 filter crystal versions:
>
> 1)  4.91-20 used on early K2s
>
> 2)  4.91-0195 used on more recent K2s and SSB options sold -before-
> approximately s/n 2570, 3/19/2002.
>
> ------
>
> 3)  4.91-20 (sorted to tighter Lm criteria at manufacturer) used from 
> about
> s/n 2570 (3/19/2002) and for a short time later until we received the
> remarked crystals.
>
> 4)  4.9136-S (remarked and sorted for Lm at the manufacturer) used on K2s
> after s/n 2570 after those in #3 above were used up. These are what we are
> shipping for all K2s and KSB2s today.
>
> ------
> The crystals used in #3 and #4 above are equivalent. The tighter Lm
> specification results in slightly less filter loss in the CW filter and a
> slightly wider bandwidth for the SSB filter.
>
> So if your K2 is in group #1 or #2, before s/n 2570 and it has the 
> 4.91-0195
> crystals in its CW or SSB filter or if it is a much earlier unit with the
> 4.91-20 crystals, you will probably see a small improvement from using the
> newer crystals. They are available at:
> http://www.elecraft.com/order_form_parts.htm
>
> Sorry for the confusion!
>
> 73,Eric  WA6HHQ


It looks like you might benefit from the matched xtal mod.

On the other hand, have you used Spectrogram to align your filters? 
 Info on this at the website.  I suspect if it sounds "tinny", aligning 
the filters well might improve things more than changing the filters.. 
 YMMV.

73, Phil