Not settled at all. We are talking about 1db and that is in simulations and
not real world contacts on 2 meter EME.
There are other considerations for comparing the two such as time involved
in waiting for a decode and other issues I have talked
about many times before. I'm not alone in concluding from real world use
that JT65b results in faster QSOs on 2 meter EME.
One very knowledgeable technically proficient European 2 meter EMEer has
made extensive on the air tests and comparisons and after doing so, refuses
to use Q65.
........ But I would like to see for myself, giving both modes every chance
for success rather than basing my observations on emotion or simulations or
not so meaningful signal report numbers. My most recent on the air tests
did not favor Q65 but I recognize that QSB plays a big role so the testing
continues. What would impress me would be for someone to find that they
know how to use both modes proficiently and conclude (on 2 meters) that
they can consistently work several small stations on Q65 60a that are less
consistent on JT65b. I may change my mind after gathering more data, but I
think something frequently goes wrong with decodes on 2 meters on Q65 60a
that happens to a lesser degree on JT65b. Joe states that even signals
that can not be seen on the waterfall are decodable on Q65. I have seen
many times (perhaps most?) on Q65 that the sync tone is clearly visible
without a resulting decode. Something is clearly different between the
simulations and real world 2 meter EME.
On Mon, Jan 30, 2023 at 9:40 AM N46Jenny <n46jenny(a)gmail.com> wrote:
The last sentence in the Joe Taylor document:
“ In my view it’s not a close call: Q65 is superior to JT65 in nearly
Should settle the issue.
On Jan 30, 2023, at 7:33 AM, Lance Collister via
Just a couple comments inserted below.
> On 1/29/2023 00:19:17, Earl Shaffer via Moon-net wrote:
> Lance - I never call a station I can't copy unless I am in a sked. I
if I did that on HF I would likely be black-listed.
probably use Q65 more.
Yes, I agree that should definitely be the case on HF! However, on 6m,
frequently NON-RECIPROCAL and only 3 stations have XPOL
capability. Often, stations do not copy me when I copy them, and
vice-versa. Therefore, I need to know who is calling and on what frequency.
If I decode them, I log their callsigns and offset frequencies. That gives
me a huge advantage if I ever see a weak trace (or orange spike) on that
offset again, since I can insert the correct callsign into the DX CALL box
and try to decode them by double clicking on their frequency with a narrow
DT. Obviously, it is extraordinarily helpful to be able to choose stations
who happen to be copying me at the same time I am decoding them, since a
quick contact can result. In lieu of knowing any such information, I just
keep trying to reply to different stations. This sometimes works, but in
cases where the moon is moving quickly through ground gain lobes for a
number of horizon-only stations, I usually run out of moon window with them
before I can try replying to all the possible stations. Perhaps it would be
best to have people only call if they were copying me, but then there is a
very real possibility that we would never complete a contact.
On a Q65 EME DXpedition, at least on VHF, as the DXpedition station, I
1. Identify what callsigns are on what offset frequencies
2. Identify what callers are copying at that moment (having reciprocal
Obviously, one serious limitation I have with 6m EME DXpeditions is that
only fixed horizontal elements, and cannot rotate my polarization. I
appreciate that a 2m EME DXpedition with XPOL may not experience these
problems to the same extent as I do on 6m.
I am certainly open to other suggestions as to how I might be able to
callers who are copying me at a particular time, since this is
such a critical issue! I have tried asking callers to send me reports if
they are copying me or seeing my trace during my last sequence, but this
changing of their messages corrupts MY AVERAGE, so is not the answer. It
also causes me to send them a different report if I start copying and
calling them again, which corrupts THEIR AVERAGE. With JT65, it was easy to
see if a station was copying me and sending me reports, even if the message
was not decoded, because the "partially decoded" message would show a #
instead of a *. This made it much easier to tell who was copying at a given
time, but such information is not available in Q65. I think that is one of
the reasons why my Q65 DXpedition contact rates have not increased
significantly compared to those using JT65A.
> If Q65 were 3db better, I would know it right away and you likely would
hard pressed to get me to switch back to JT65b on 2 meter EME.
Earl Shaffer, WB9UWA
Yes, 3 dB difference would be HUGE! That is about what K1JT found
between Q65 and
JT65A NOT USING CALL3.TXT. It sure would be great if
another 3 dB could be added to Q65 by using CALL3.TXT to at least hint at
what callers were calling at various offsets! But this does not appear to
be in the cards.
Joe's conclusion from his pileup experimentation 2 years ago was that
was about the same as JT65A when an unknown callsign was decoded
using CALL3.TXT. Since JT65A is about 1 dB more sensitive than JT65B, it
would appear that anyone who is interested in working weak stations on 2m
EME should be using Q65-60A (especially if they are on a one-on-one
prearranged schedule, where both calls are known in advance). But there is
further sensitivity in the Q65 AVERAGE (even with multiple callers across
the bandpass), as long as the caller's message does not change - that adds
additional dB of sensitivity. Joe's letter is attached.
So, in conclusion, I feel Q65-60A is at least slightly more sensitive
in a VHF DXpedition situation. However, there are still a couple
very significant factors not related to sensitivity that play a large role
in the success of a VHF DXpedition. Obviously, information regarding both
of those issues can be provided via the internet, although then the
contacts are not random, and the issue is raised about how much information
can be provided outside the radio channel. Personally, my preference is for
all the information to be provided via the radio.
GL and VY 73, Lance
Lance Collister, W7GJ(ex WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8, E51SIX,
5W0GJ, E6M, TX5K, KH8/W7GJ, V6M, T8GJ, VK9CGJ, VK9XGJ, C21GJ, CP1GJ,
S79GJ, FO/W7GJ, TX7MB, TO7GJ)
P.O. Box 73
Frenchtown, MT 59834-0073
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