[R-390] A Few Questions for the Group

[Bob Camp]

Hi,

The level at the IF output varies quite a bit with the setting of the IF
gain control and the meter calibration pot. I *think* it ran about -5 to -10
dbm with a fairly full deflection last time I checked it on a couple of
radios.

The general consensus on redoing the '390 these days is to make any changes
reversible. We are going from a modify the heck out of everything approach
to a collect and conserve attitude. Mostly it is driven by the increasing
price of the radios and the recognition that a lot of significant radios are
getting darn hard to find.

If you compare either of the 390's to a modern radio they are plenty
sensitive. If you want to knock them you have to grab something like a
RF-590A and compare in band mutli signal overload numbers on 10 meters or
something weird like that. The 390 radios are quite good in that respect,
there are just some out there that are a little better. The ER mods mainly
try to make the radio more sensitive. Usually this is at the cost of
overload performance. I don't think it's a good idea in most applications.
The mods are well thought out and they should work. If you are going to do a
set of these those are the ones to go with. I just don't think that the
result will be worth the effort.

I think you will find that there is plenty to do just keeping a flock of
390's running. If you don't have a flock yet, just hang around. You'll catch
the bug. A couple of 390A's (early, mid and late contract maybe, say two or
three of each). A pair of 390 not an A to compare to. That should be enough
to soak up all of your spare time :)

    Take Care!

        Bob Camp
        KB8TQ


----- Original Message -----
From: "MURPH" <rickmurphy1001@earthlink.net>
To: <r-390@mailman.qth.net>
Sent: Monday, February 03, 2003 6:05 PM
Subject: [R-390] A Few Questions for the Group


> Hi all
> I am getting ready to dig deep into the R390A that I have and I have a few
> questions for the group.
> 1. Has anyone changed the tube type and circuitry to support  quieter
> tubes as described in ER magazine #26 June 1991 ? I.E. Change most of the
> IF tubes to 6JH6's. Change the RF amp to a 6GM6. Change most of the mixers
> to 6HA5's.
> 2. Can anyone strap an oscope to the IF output on the back panel to get a
> measurement with the carrier level meter at 50db?
> 3. What is the rg number for the mini coax that is used through out?
> Thanks in advance
> Richard
>
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