I sent my reply to Nick but maybe others might be interested. The Drake
PIN diode deterioration is not my opinion; Drake has mentioned this in
tech articles in the distant past, where I first learned about it.
Steve
On 9/27/2018 10:48 AM, STEVE wrote:
I'm mostly familiar with the Drake R8 series, having worked on two
R8Bs, converting them to true VLF-HF reception instead of the
no-sensitivity below about 130 kHz. I don't know if the R7 uses PIN
diodes. I'm not directly aware of other brands that used PIN diodes in
the front end. Drake also used 200 ohm input switched band filters,
with transformers to convert from 50 to 200 ohms, and the reverse on
the output of the filters. Those diodes are associated with that and
possibly are more sensitive to deterioration at the higher impedance
than where PIN diodes are usually used in 50 ohm systems.
Steve
On 9/27/2018 10:40 AM, Nick Hall-Patch wrote:
Thanks for pointing that out Steve. Are there other receivers of
that vintage that might also suffer from deteriorating front end
PIN diodes?
best wishes,
Nick
At 17:38 2018-09-27, STEVE wrote:
Drake uses PIN diodes in the front end switched band filters of the
R8 series (and at least the SW8); those diodes deteriorate over
time, significantly reducing sensitivity. Unless you had those
diodes replaced at your service it's likely that's why your Drake is
less sensitive than the Elad.
Steve
On 9/27/2018 9:34 AM, C B via IRCA wrote:
An OK morning for TPs in CO. I did a preliminary comparison between
my Elad FDM-S2 and the Drake R8A. As Bogey said "This could be the
beginning of a beautiful friendship". I started with comparing the
two JJ powerhouses, JOUB and JOIB. The Drake had weak, barely
discernable audio with both the ALA 1530ln and the NW Corner-Fed
loop. The Elad produced fair to good audio readily understandable
to a JJ speaker. I did not expect the difference to be so evident.
I had my R8A serviced a couple of years ago by a former Drake tech,
so while a bit long in the tooth, it's working fine. More to come....
This morning's results:
594 JOAK w/male in JJ weak (w/Elad, just a het w/Drake)
747 JOIB w/male in JJ good (w/Elad, weaker w/Drake)
774 JOUB w/male in JJ good (w/Elad, weaker w/Drake)
828 JOBB w/ weak audio (w/Elad, threshold audio w/Drake)
A decent assortment of hets.
73 and Best of DX,
Craig BarnesWheat Ridge, CO
Elad FDM-S2, Drake R8A, ALA 1530ln, NW Corner-Fed loop, Quantum Phaser
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Nick Hall-Patch
Victoria, BC
Canada
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