[R-390] Help getting unstuck!

[charles bolland]

Craig,

Let us know what it is when you fix it.

Tnx

Chuck

----- Original Message -----
From: "Craig C. Heaton" <wd8kdg at worldnet.att.net>
To: <Flowertime01 at wmconnect.com>; <r-390 at mailman.qth.net>
Sent: Sunday, April 03, 2005 09:09
Subject: RE: [R-390] Help getting unstuck!


> Roger/All,
>
> Had the opportunity to play radio this evening. Connected the signal
> generator and started having fun. With a short test lead connected to
either
> antenna input WWV at 10Mhz and some foreign broadcast made its way to the
> speaker. All four mechanical filters are working, BFO is good, Crystal
> calibrator is close, but nothing below 8MHz. So there are a few bugs to
work
> out.
>
> Think I've read some of the threads on the 8MHz problems. Going to fix it
> next.
>
> later.......and Tnx,
>                   Craig
>
> -----Original Message-----
> From: r-390-bounces at mailman.qth.net
> [mailto:r-390-bounces at mailman.qth.net]On Behalf Of
> Flowertime01 at wmconnect.com
> Sent: Friday, April 01, 2005 8:38 PM
> To: r-390 at mailman.qth.net
> Subject: Re: [R-390] Help getting unstuck!
>
>
>
> Can't seem to get the top slug in T501 to move.
>
> Craig,
>
> Sounds like a chance to stop and test.
>
> Run the 455 into the IF deck and do a signal to noise test. If you can get
a
> 28 to 1 signal to noise the coil is close enough and effort to adjust the
> stuck slug will exceed return on investment. If its close just leave it
> alone. If
> its not close then maybe you will be loosing some fidelity in the 16K band
> width.
>
> Use the Adjustment of Gain Adj Potentiometer. Paragraph 73 in TM
> 11-5820-358-35. you want to run 150 uv of 455 into the IF deck. set the
gain
> adjust for -7
> volts on the diode load. With 30 percent modulation you should get about
.5
> watt of audio across the 600 ohm output. We metered the headphone output
> with a
> test lead that ended in a phone plug. You can meter dB with most analog AC
> volt meters and the instruction book (page of paper) for the meter.
>
> Turn the signal generator modulation off. Now you have just a 455 carrier
> signal. The audio output should have dropped 30 dB and there should still
> be -7
> volts on the diode load.
>
> If you cannot get 30 dB signal to noise here, start swapping tubes around
> and
> trying to do some alignment. Trouble is there is no easy way to determine
if
> your IF deck was stager tuned or aligned at 455.
>
> So try to perform the stager alignment procedure as detailed in the TM
> first.
> If you are loosing gain, go for the straight alignment.
>
> Just leave the stuck slug for the very end. Get all the other bugs out of
> the
> way first. Get good tubes in and do the best alignment you can get other
> wise.
>
> If you get up to about 28 to 1 just leave that stuck slug alone.
> Only after you get every thing else as best you can and you know by
> measurement that the IF deck is not up to minimum then get worried about
> that slug.
>
> Get the cover off the can so you can see what's moving.
> The hot air hair dryer is the least offensive way in.
> Most of the time it will melt down some of the wax.
> Heat and soften the gunk.
>
> You can get an IF deck from Fair Radio less crystal filters and tubes, and
> BFO and ballast tube. It will have a T501. The IF cans (T501, T502, T503)
> are
> all the same.
>
> Push comes to shove and you conduct a destructive test, ask here on the
> reflector, someone likely has the part stuck on some of there collected
> spare parts
> and would make you an offer your not likely to refuse.
>
> Good luck and be gentle.
>
> Roger KC6TRU
>
>
>
>
>
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