Re: Murania on 5 MHz?

Dwayne R <masterdr@...>
 

Hello Jim. . .

I realize I have not built or seen the schematic of this radio (Yet). Because I just got through ordering 2 of them.
But. . .

For a tuned circuit, the more inductance you add, the lower the frequency. . .

Thus, you adding of 15 turns on top of a existing coil that is made for 1.6 mhz should LOWER the frequency,
instead of raising the frequency. I would think that you would want to take the existing coil, unwrap about
X number of turns, and tap on to that point, then rewrap the coil back up. . .
Placing a switch that excites the tapped point, and when turned off, uses the whole coil.

Please forgive me if I am wrong... Especially since I have not built or have the schematic in front of me!

Dwayne (Ka0aam)



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On Tue, 10/23/18, Jim WB2LHP in MI <jmarco1955@...> wrote:

Subject: Re: [4SQRP] Murania on 5 MHz?
To: main@4sqrp.groups.io
Date: Tuesday, October 23, 2018, 2:52 PM

Hi
Dave...The short answer is "maybe"...
I've been thinking about this
myself...According to the data sheet, the TA7642 tops out at
about 3MHz but I have read where people have used them at
frequencies up to 10MHz...Here's a possible scenario you
can try...
If you are
using the original 37-turn coil, you can add another 14
turns to the coil and use the old end as a center tap...This
creates a second winding of around 15uH...Depending on which
coil you short out, you will get two tuning ranges...One for
the AM broadcast band, the other for roughly 1800KHz to
6MHz...I haven't tried this myself but it should
work...
Jim
WB2LHP
On Tue, Oct
23, 2018 at 2:43 PM Dave Redfearn <@n4elm>
wrote:
Would it
be practical to mod the Murania to tune between 5 & 6
MHz?
73 - Dave, N4ELM

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