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Couple things here....<br>
Think about simply changing out <i>all</i> of the tubes, if
just on general principles...you might find it makes quite a
difference in terms of performance. I've been learning the hard way
from an SB-101 I've been restoring that a tube tester doesn't detect
mediocre tubes that should be replaced. Also, on general
principles, replace <i>all</i> of the electrolytics with newer
units. This might get rid of your hum..<br>
Secondly, I used a newer generation Heathkit as my first novice
receiver--the GR-64. It's sensitivity was amazing, but of course,
it's selectivity was as wide as a barn door when used less the
matching Q-multiplier. But I used a technique my elmer taught
me--get selective to the <i>tone</i> of CW signals. Now while the
64' only had four tubes, I think it will outperform any AR-3, at
least in my experience. <br>
Of course, if you decide to "re-kit" the unit or another, test
each resistor and cap prior to installation. I'm currently
rebuilding (from a re-kit) an AR-3 at my second home--been working
on it on and off when it snows too hard at my 2nd home in Mammoth
Lakes..and as a result, it's still not finished after about 10
years....<br>
Guy<br>
<img src="cid:part1.03060809.04010107@js-net.com" border="0"><br>
<div class="moz-cite-prefix">On 4/18/2016 9:24 AM, Kenneth G. Gordon
wrote:<br>
</div>
<blockquote
cite="mid:57150A2E.24086.12F86B97@kgordon2006.frontier.com"
type="cite">
<pre wrap="">I have finally been able to start re-building my first Novice station, an AR-3 and a DX-35.
I have the transmitter situation well in hand, and am now beginning the receiver end.
Over the past several years, I (somehow) aquired three AR-3s in various states of
completion and condition.
Yesterday and last night, I pulled the most complete one out of the pile and began to do
some work with it.
The first thing I did, after checking the power supply and finding it "adequate", was to align
the receiver.
That went reasonably well, and the dial accuracy is now about as good as it ever was, I
would guess.
2.5, 5 and 10 MHz WWV appear very close to where they should be on the dial, and the BC
band accuracy is also very close. Inputting a signal at 25 MHz also shows up very close on
the dial, although on band "D", the 10 MHz end seems almost dead. I'll work on that later.
My main issue right now is that when I turn the BFO on, I get a HUGE amount of hum out of
the speaker and nothing much else. With the BFO off, there is a bit of hum, but it is not
particularly noticable.
At this point, I suspect either the 12AV6, or something still not quite right in the power
supply. I will make a closer examination of the power supply, and will replace the 12AV6
asap.
So, I am wondering if anyone else here has run into a similar situation with the AR-3 and
what you may have done about it?
As I suspected, the AR-3 is a VERY marginal "communications" receiver. As I may have
remarked here some time ago, I cannot now see how we ever used such receivers, and
even worse ones like my original Hallicrafters S-41G, to actually communicate with when we
were young and didn't know any better. I was first licensed as a Novice in 1956 when I was
still 13 years old.
I am also thinking of "re-kitting" the other two AR-3s I have into at least one good one, just
to make sure what I have is built properly.
Might anyone have one of those small, transparent "dials" which were originally included as
part of the bandspread capacitor that they might part with? Of the three receivers I have,
only one still has that: the one I worked on last night.
BTW, replacing the 12BE6 with a new 12CS6 makes a very noticable improvement in the
receiver's sensitivity on the higher bands, and the receiver also appears to be more stable.
vy 73 for now,
Ken W7EKB
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</pre>
</blockquote>
<br>
<div class="moz-signature">-- <br>
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