Draft — follow-up email to Fanstel¶
Status: draft, not sent. Written 2026-08-10 by /todo from Todos.md → Chase Fanstel on the BM20C FCC grant.
Send as a reply on the existing thread — you emailed them 2026-08-04 and they replied; keeping it in-thread means they have the context and you don't have to reintroduce yourself.
Everything asked here is tracked in: Todos.md (the Fanstel step list) and FCC Certification.md §7.
Placeholders to fill: [ORDER NUMBER], [DATE ORDERED], [NAME] if their reply was signed. Nothing else.
Why it is shaped like this¶
Seven asks is a lot for one email, and a vendor will answer a numbered list where they'd skip a paragraph. So: two sentences of context, then numbers, then nothing. No pleasantries at the end that invite a reply which answers none of them.
The order is deliberate. Items 2–4 are the certification chain, which is what BLK-15 actually turns on. Items 5–7 are cheap for them and save you a board spin.
2026-08-10 — item 1 was answered before this was sent. Fanstel emailed to say both the WM02C and the BM20C are shipping and on their way, which discharges BLK-15's supply half for this order. It is rewritten below into a tracking-number ask rather than deleted, because a carrier and a number are what make "on their way" checkable, and because dropping item 1 would renumber a list whose ordering the rest of this document refers to. The grant half of BLK-15 is untouched by that reply — a module in a box is not a module with an FCC ID.
One thing is deliberately not asked: whether the BM20C will be certified in time. They already answered that as precisely as they are going to ("this month"), and asking again invites the same non-answer. Asking for the grant number instead makes the question falsifiable — either it exists or it doesn't.
Subject¶
Body¶
Hi [NAME],
Thanks for the earlier reply. I went ahead and ordered a BM20C and a WM02C on
[DATE ORDERED], order [ORDER NUMBER], and I am now designing the host board
around them and getting FCC test quotes, so a few specifics would help a lot.
1. Thank you for confirming both modules have shipped. Could you send me the
carrier and tracking number when you have a moment? I would like to plan the
bring-up week around the delivery date.
2. Once the BM20C's FCC testing completes, could you send me the grant number
in writing? My test lab needs it before I can book a slot, and a booking is
2-6 weeks of lead time, so it is the item on my critical path.
3. With the grant, I will also need the grant conditions and the test report:
certified antenna type, peak antenna gain, and declared maximum conducted
power per mode. The draft datasheet (Ver 0.82) does not carry these, and my
RF exposure calculation currently uses the +8 dBm figure from it. If the
grant declares something different, I need to know before I file.
4. Can you confirm that the part shipping to me is the part being certified?
I want to be sure of BM20C rather than BM20BC, and nRF54LM20A rather than
nRF54LM20B. I noticed your evaluation boards carry the B variant, and I have
designed for the A.
5. A footprint question. I have pulled BM20-library260729.zip and the BM20C
specification from your nRF54/70 document page, and they do not quite agree
with the footprint I have been building to: mine draws the module body as
14.8 mm long, while the datasheet's 10.3 mm RFI shield plus 5.5 mm antenna
area comes to 15.8 mm. Which is the dimension I should place the antenna
keepout against? A millimetre matters here, because the keepout is what
decides whether the antenna clears the board edge.
6. A layout question neither datasheet answers: my board carries the BM20C and
the WM02C together, so there are two 2.4 GHz chip antennas on one 40 x 42 mm
PCB. Is there a minimum separation you require or recommend between them, and
is it acceptable for both antenna areas to overhang the same board edge? Your
mounting guidance covers one module on a board and does not address a second
radiator nearby.
7. On the fallback: if the BM20C timeline slips, I would build a Bluetooth-only
version. Your datasheet for that part is titled BC15C and my earlier notes say
BM15C - could you confirm the exact part number I should be ordering? And is
it genuinely footprint-compatible with the BM20C, or are there differences I
would need to respin for?
8. Last one, and the smallest: I am using WM02C-Power-Setting_radiotest_prj.txt
from your nRF54/70 document page for the antenna-gain and band-edge backoff
CONFIG values, since I understand those settings are part of the module's
grant conditions. Could you confirm that file is current, and that it is the
right one for a US Part 15 build? I would rather use your values verbatim
than transcribe them out of the PDF.
Thank you,
David Macpherson
What to do with the answers¶
| Answer | Where it goes |
|---|---|
| Grant number and status | Todos.md → Fanstel block; unblocks OCT-05 booking. Half of BLK-15. |
| Grant conditions (antenna, gain, max power) | FCC Certification.md §5 — re-run the SAR arithmetic if the declared max differs from +8 dBm. The ratio 2.5 has only 0.5 of headroom against the 3.0 threshold, so a +2 dB surprise moves BLE out of exclusion and changes what you're buying from the lab. |
| Part-number confirmation (A vs B, BM20C vs BM20BC) | firmware_spec_v3_nrf.md §1 — the A/B split is an NPU difference and could affect the NCS board target. |
| BM20C body length (14.8 vs 15.8 mm) | Antenna Placement.md §2 and §5 — the BM20C antenna-area coordinates there are drawn from the 14.8 mm silkscreen, and a millimetre moves the keepout. |
| Antenna separation answer | Antenna Placement.md §1 — it replaces the inferred 30 mm, which is currently a range recommendation being used as a design limit. Fanstel's own number beats the inference. |
| BC15C part number + footprint compatibility | BLK-15's fallback line, which currently rests on "to my knowledge." |
| WM02C CONFIG file | firmware_spec_v3_nrf.md §1.1 — it is a grant condition on firmware, and the file is the source of truth over the datasheet table. |
If they don't reply within about a week, item 2 is the one to chase by phone rather than email. It is the only item on the critical path — OCT-05 books a lab slot at 2–6 weeks of lead time, and the grant number is what a lab needs before it will take the booking.