[R-390] Frequency meter

[Michael Murphy]

Here are a few links. The DFD series is popular.  MM WB2UID

http://www.aade.com/dfd.htm#prices

http://www.eham.net/reviews/detail/1457

http://www.ohr.com/dd1.htm

http://www.radioadv.com/ham_radio_equipment/FreqMC/A2.htm

http://www.qsl.net/k5dkz/r4digital.html

http://www.circuitsonweb.com/resources/Projects/fc50.html

http://www.aade.com/Applic~1.htm


----- Original Message -----
From: "Bob Camp" <ham at cq.nu>
To: "Charles B" <ka4prf at us-it.net>; "R-390 HF Receiver List"
<r-390 at mailman.qth.net>
Sent: Wednesday, September 01, 2004 6:22 PM
Subject: Re: [R-390] Frequency meter


> Hi
>
> As the other posts have mentioned it's not a simple thing.
>
> A lot depends on how accurate you want to get. RTTY and SSB are the two
> things that most people would like to tune accurately. With AM the
> bandwidth of the filters makes a 10 or 100 cycle error a lot less
> important.
>
> If you are going to tool up to do a full readout for SSB or you would
> need to measure:
>
> 1) The first crystal oscillator
> 2) The second crystal oscillator
> 3) The VFO
> 4) The PTO
>
> The digital stuff to do that isn't terribly expensive these days, but
> it does make noise.
>
> Once you had all the frequencies measured then oddly enough you would
> have to know what band you are set to. It turns out that several of the
> crystals are used for more than one band so there is no direct and
> simple way to guess the band in every case.
>
> That all sounds like a lot of work and I'm lazy. If I was going to do
> it I'd fake it:
>
> No matter what you need some way to track the band switch. Say we slave
> a pot to the shaft and measure the resistance.
>
> The 17 MHz ovenized crystal isn't going to drift much I would simply
> measure it's frequency with a bench counter and store the result
> somewhere.
>
> The same thing is true to a lesser extent for the crystals in the
> crystal deck. They do drift but maybe by sixty cycles. I would just
> measure them and store their frequency as well.
>
> That gets us to the BFO and the PTO.
>
> There is an old military mod that puts a multi turn gear drive and
> readout on the BFO shaft. The net result is the ability to reset the
> BFO very accurately. If you can lock down the BFO shaft fairly well
> (maybe mechanical detents) you can get around reading the BFO.
>
> All that's left is the PTO. You can either count it's frequency or try
> the slave a pot to the shaft trick.
>
> The cute thing about doing it al with pots would be that you have no RF
> counters at all. You are dependent on the radio not drifting but that's
> what the 390 is known for.
>
> Definitely a bit far from the "well enough alone" zone thought ....
>
> Take Care!
>
> Bob Camp
> KB8TQ
>
>
>
> On Sep 1, 2004, at 9:37 AM, Charles B wrote:
>
> >
> > Is there any place inside the R-390A where a frequency meter can
> > attached to get a frequency reading?
> >
> > Chuck
> >
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