[R-390] R-390a SS Conversion

[Mack McCormick]

My use case for this radio is primarily AM on 80 and 40M plus the local AM
broadcast band.

I have not noticed intermod in these use cases but I have not measured.

73,

Mack
W4AX
https://www.qrz.com/db/W4AX


On Sat, Oct 30, 2021 at 7:30 PM David Wise <David_Wise at phoenix.com> wrote:

> How’s the cross modulation?
>
>
>
> Dave Wise
>
> SWL (inactive)
>
>
>
> *From:* r-390-bounces at mailman.qth.net [mailto:
> r-390-bounces at mailman.qth.net] *On Behalf Of *Mack McCormick
> *Sent:* Saturday, October 30, 2021 3:42 PM
> *To:* Alan Victor
> *Cc:* Sandeenpa at yahoo.com; R-390 Group
> *Subject:* Re: [R-390] R-390a SS Conversion
>
>
>
> Alan,
>
> I did not map out the impedance levels, perhaps Charles did. All stages are
> solid state. MPF102 JFETs. The original power supply is removed and the
> radio electronics are run on 24VDC. I did take several gain measurements.
> There was a real problem with getting the gain of the 1st IF correct.
> Coupling between stages is pretty critical.
>
> Mack
> W4AX
>
> On Sat, Oct 30, 2021 at 12:31 Alan Victor <amvictor at ncsu.edu> wrote:
>
> > Hello Mack.
> >
> > Curious if you and Charles mapped out the various impedance levels and
> > required gain from stage to stage? Did you convert every stage to SS or
> > targeted specific ones?
> >
> > Apologize if this question is answered in one of your posts.
> >
> > Thanks for the info!
> >
> > Best73' Alan W4AMV
> >
> > On Sat, Oct 30, 2021 at 6:55 AM Mack McCormick <w4ax.mack at gmail.com>
> > wrote:
> >
> >> Perry,
> >>
> >> Charles provides an excellent template to SS your R-390a. He is a
> >> wonderful gentleman and we collaborated often. I am the only other known
> >> person to complete the project. Charles and I went through four design
> >> changes as I SS's a R-390a. It is a rock solid design now.
> >>
> >> Without knowing your technical/construction skills let me caution this
> is
> >> not a trivial project and requires at least intermediate level skills.
> >>
> >> I posted about my SS conversion on this list within the past three
> months.
> >> You can search for the thread if interested.
> >>
> >> Here are pictures of some of my work. Please note: The PC boards I made
> >> for
> >> the SS tube replacements are no longer the current design. I will
> provide
> >> you with the version 1 files but you will need to update them to the
> >> latest
> >> design using KiCad (free on DigiKey).
> >>
> >> Good luck and I'll be interested in your results if you undertake this
> >> project.
> >>
> >> https://photos.app.goo.gl/11AjyNCi2zV3T8LaA
> >>
> >> 73,
> >>
> >> Mack
> >> W4AX
> >> https://www.qrz.com/db/W4AX
> >> ______________________________________________________________
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> >>
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> > --
>
> 73,
>
> Mack
> W4AX
> https://www.qrz.com/db/W4AX
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