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Mike, I was measuring current draw between the battery and the radio. ?I'll try and get some measurements tonight when I get home from work. ?Thanks for the quick response!?

Drew

Correction: ?The SW Broadcasters are assigned frequencies on 5khz increments. ?But a stock Bitx40 should still be accurate enough to know which 5khz step the broadcaster is on.

I ordered my latest Bitx?on 5/19. It arrived today 5/30 so 11 days with the standard shipping method to?South Carolina.
Marked 4/790V

v/r
Fred W4JLE

I sincerely doubt the crystal used on an $3 ebay Pixie would be any more accurate than the crystals used on the Bix40.?

Allard's suggestion of calibrating to one of the SW AM Broadcast stations is a good one, as broadcasters are almost always on 10khz increments. ?All AM SW Broadcasters should be above 7.2mhz, and all their images should be below 7.2mhz, ?avoid using those images. ?The tuning knob will tune through an image 4 times as fast as a normal signal since it is received using the 4'th harmonic of the VFO.

If we assume the 25mhz crystal in the Raduino and the 12mhz BFO crystal on the Bitx40 main board are both correct within 100 parts per million, we might have as much as 200ppm error on a stock Bitx40. ? ?200 ppm at 7mhz is 200*7mhz/one-million = 1400 hz. ? Most rigs should start out much closer than that, so will be easy to tell which 10khz increment some SW Broadcaster is on.?

From post 25393: ? "In addition to the 7.2mhz birdie, we also have a problem with images from SW broadcasters getting through due to the 4'th harmonic of the VFO mixing with the incoming signal. ?For example, when receiving at 7.1mhz, the vfo is at 12-7.1 = 4.9mhz, the 4'th harmonic of which is 4.9*4 = 19.6 mhz. ?That 19.6 mhz is present in the diode ring mixer, and mixes with a signal at 7.6 mhz to create a 12mhz if signal."

Jerry, KE7ER

Another good way to do the calibration is to purchase one of the little inexpensive Pixie QRP transceivers. It puts out a CW carrier on 7040 MHz. Makes for a cheap signal generator. ?You can find them on Amazon and EBay.?

Why not just send it to their registered paypal mailing address?

Vince.

--
Michigan VHF Corp.

Great Richard. I have the same situation. HFSigs has made it fun and accessible to get on HF for under $100.?

I made a complete box for my Bitx40 before ever putting it on the air... I've never attached the cover because I like looking at the circuit and thinking through its function. I don't think that would be the case with even a used HF transceiver. ?

It's great doing mods with all the support here and elsewhere on the net. I believe the community makes this radio what it is.?
HFSigs vision likely anticipated the same.?

73

Jamie VA3RLF?

All:

I was sending out order notices from people who had written me about the board and sending the response to the group instead of the individual. (A lot of people placed orders, but did tell me where to ship the board(s).) I'll try to pay closer attention down the road.

Jack, W8TEE

Use a website like websdr.org to tune into a strong broadcast, and then try to find that same broadcast on your bitx.

Of course, this assumes the SDR station is showing the correct frequency.

Alternatively, if you do make contact with someone who has a more precise rig, ask them what their exact frequency, then use that information to calibrate.
--
Darren, W9ZIM

Terry,

Here's another trick:
in the evenings there are quite a few strong broadcast stations in the
section above 7200 kHz. You should be able to hear them even when you live
"in the sticks".
As these are broadcasting an AM signal with unsuppressed carrier you can
use them for calibration your radio.
Broadcast stations are usually precisely on frequency at 10 kHz intervals.
You will hear a strong whistle when you tune to a broadcast station. As
you tune trough the signal, the pitch of the whistle will go from high to
low until it is zero and then go up again.
The point where the whistle is exactly zero Hz is "zero beat". You can use
this as a reference point for calibrating your radio. In calibration mode,
adjust the offset value so that the whistle is zero Hz.

73 Allard PE1NWL

Hi Allard,

It was very clear tone. I will check again and inform you

73 Yiannis, SV5FRI

I hear you loud and clear. Even if it's not a 0 or 5.
Ken,T

hi allard

the problem that i have had with calibration is finding a carrier on an exact frequency

i live in the sticks so finding a local station is hard to come by

73 de terry gm4dso