Note: groups.io will be down for maintenance on Monday, September 26th, starting at 9AM Pacific Time (4PM Monday September 26, 2022 UTC), for approximately one hour.
Re: Russian Surplus 140mm x 8mm Ferrite Rod Prices on eBay
Hi Guy,toggle quoted messageShow quoted text
Thanks for this interesting question, which I'm sure that other DXers
have also wondered about.
The shortest Russian surplus ferrite rods that I have actually tried
are the 140mm x 8mm ones, obtained from both "Alexer1" and "Sovtube."
These have proven to be very effective in compact antennas like the 7"
diameter medium-wave "Affordable" FSL model (the one you took to Oregon
during your vacation). Based on the excellent performance of these
140mm x 8mm rods (and the 160mm x 8mm and 200mm x 10mm ferrite rods of
the same 400 permeability that have excelled in other FSL's) I have no
doubt that the Russian surplus 100mm and 65mm-long rods would also give
great performance, at a significant cost advantage. The shorter length
may make it difficult to get enough turns of Litz wire to make a
Longwave FSL design without using a variable capacitor of more than 381
pf capacitance, but for a medium wave FSL design, that should not be an
issue. As always, the important factors for good DXing performance will
be the accuracy of the cylindrical ferrite sleeve (all the ferrite rods
should be lined up, and pointing exactly the same way), the use of
high-quality Litz wire (660/46 is recommended), and the use of a
high-quality variable capacitor to take maximum advantage of the high-Q
tuning system. A/B testing here has also shown that the FSL's DXing
performance can be enhanced simply by placing the antenna up[ on a 5'
high PVC stand.
The eBay ferrite sellers usually price their rods according to the
purchasing demand, and the current "hot item" seems to be the 140mm x
8mm size. The 160mm x 8 mm size was also a hot item back in the
spring-- until Kevin and I apparently cleaned out the sellers of that
particular size. The 200mm x 10mm size was ordered in serious quantity
around May and June, but the sellers were not able to make a price
increase stick (presumably because of a huge supply of these rods,
owned by multiple sellers). The smaller sizes haven't really had much attention at all, so they would probably be a great option for
73, Gary (from across town)
From: thinkdx <dx@...>
To: ultralightdx <ultralightdx@...>
Sent: Thu, Sep 1, 2011 10:58 am
Subject: [ultralightdx] Re: Russian Surplus 140mm x 8mm Ferrite Rod
Prices on eBay
What do you think of the shorter rods as alternatives, such as the 65mm
or 100mm long versions? For the same general price you could get more
rods and make a larger diameter loop.
Which begs the question-- which is better: shorter ferrite rods with
bigger overall loop diameter, or longer ferrite rods but smaller loop
73 from across town...
Puyallup, WA USA
--- In ultralightdx@..., D1028Gary@... wrote:
63 rod FSL) can be obtained from him for $104 (US Dollars) includingat
in one single purchase. The sellers will probably try to raise thefor