[R-390] Receiver 51J-4

[Dan Merz]

Mike,  we're all waiting to see how the 1 1/4 inch 390 slug can be cut to
the 1 1/2 inch length of the 51J4 slug ?  I can't tell on my working
receivers which type is longer but I'm assuming Pat had both out to compare
the length. I agree with you that searching for more 51J4 slugs would be the
best path,  even more so if the 390 slugs are shorter.  best regards,  Dan  

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of mikea
Sent: Thursday, June 30, 2005 10:23 AM
To: r-390 at mailman.qth.net
Subject: Re: [R-390] Receiver 51J-4

On Thu, Jun 30, 2005 at 01:12:31PM -0400, Patrick wrote:
> Not an R-390 question, but with all of the knowledge here, perhaps I 
> can get some help.
> 
> The 51J-4 has tunning slugs about 1 1/2 inches long, what would be the 
> impact on replacing broken ones or all of them with slugs that are 1 
> 1/4 inches long? (R390 type) I can make the length of the flexible 
> cable  the same as the one on the 51J-4...or should it be 1/4 inch 
> longer???
> 
> Thanks in advance to any and all advive.

I can't see that it will be a drop-in replacement. If the 51J-4 slugs are
the same material as the R-390 slugs, then I suspect the inductance will go
up some -- maybe a lot -- with the R-390 slugs. If they're not the same
material[1], then you'll need to experiment. 

OTOH, if they _are_ the same material, then you should be able to cut the
R-390 slugs down to the right length for the 51J-4. I'd try a Dremel and a
cutoff wheel. Wear eye protection. 

But try to find some 51J-4 slugs first, please. R-390 slugs aren't all that
common any more, and there probably won't ever be any new ones. 

[1]	Just how does one go about determining this? GDO, standard coil,
etc.,
	and measure inductance change per unit length?

--
Mike Andrews, W5EGO
mikea at mikea.ath.cx
Tired old sysadmin
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