[ARC5] My 10 meter BC-454...

[Richard Knoppow]

----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: "Leslie Smith" <vk2bcu at operamail.com>
Cc: "ARC-5 List" <arc5 at mailman.qth.net>
Sent: Wednesday, January 23, 2013 9:31 PM
Subject: Re: [ARC5] My 10 meter BC-454...


> On 24 Jan 2013 at 16:21, Leslie Smith wrote:
>
>> Ken,
>> Speaking generally, stability diminishes with the square 
>> of the
>> frequency, so IF a 3 to 6 MHz receiver is stable within 
>> (say) 4 KHz at
>> 3MHz,
>
> Actually, it is much better than that.
>
> BTW, in this case, by stability I meant "mechanical" 
> stability: i.e., if you tap
> on the case, it wobbles. The HFO winding is floating in 
> this abomination.
>
> I'll fix that tomorrow. What I will probably do is to 
> completely rewind all three
> coils. When I finish with them, I'll glue them down so 
> they won't move.
>
> Also, according to the original article, the original 
> tuning slugs are supposed
> to be put back in the coils after they are modified. That 
> has never been done
> for this one. Therefore, it won't tune below 28.2 MHz, but 
> will tune up to 40
> MHz., and the antenna trimmer is supposed to be about 
> centered at the
> high-end of the band, but it is fully meshed instead. 
> Obviously, the
> inductance of all the coils is too low.
>
> Ken W7EKB
>
     I don't know what you plan to glue the winding with but 
I discovered that its easy to make home-made Q-dope.  I 
dissolve Styrofoam, from cups of shipping material, in MEK. 
I think Xylol also works. Use pure white foam, drinking cups 
work well. Crumble them and let them soak in a glass 
container filled with the solvent. They will dissolve very 
quickly at first and more slowly as the solvent reaches 
saturation.  I stopped when the mixture was about the 
consistency of honey.  The dope takes several minutes to 
set. You have enough time to maneuver things. I think full 
hardness is reached in perhaps half an hour or a more.  The 
finished dope should be uncolored and not cloudy. It may 
need to steep for several days to become fully cleared.
     I tested my dope on home made coils on a Boonton 
Q-Meter at several high frequencies (up to about 250 Mhz). I 
wound the coils on thin cardboard tubes (from toilet paper). 
My coils had very high initial Q and the Q showed no change 
at all when covered with the dope.
     Q-Dope is still manufactured but may be hard to get and 
I am not sure of whether there are restrictions on shipping 
(you can ship anything if you are willing to pay for it). 
This stuff is easy to make and very cheap. You do need a 
_glass_ container with a lid that is not affected by the 
solvent.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com