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Call Sign : 26-CT-4484 Posts : 88 Times Thanked : 2 Join date : 2021-10-17 QTH or Location : Torquay Equipment Used : cobra 148 glt dx starlker9 fdx, icom 706 mk1
Subject: need help Sat Aug 06, 2022 9:48 pm
I have brought a ft 840 off eBay set it up today and found out my modulation is like I'm under water if i turn the power down it becomes a little more auditable not by a lot, change power supply still no change I hope I have not brought a lemon anyone got any ideas all welcome. regards Dave
Victor CT Directors
Call Sign : 26-CT-3228 / M7VIC Posts : 5778 Times Thanked : 352 Join date : 2019-11-10 QTH or Location : Bedford Equipment Used : Various
Subject: Re: need help Sun Aug 07, 2022 6:07 am
Hi Dave,
A bit more information may be useful before anyone can possibly help you.
Is the modulation problem on any particular one of the modes? (AM/SSB/etc.)
Does the problem show itself regardless of which frequency/band you are on?
What does sounding like 'underwater' actually mean? Is it like the sidebands are not being resolved, (Mickey Mouse/Donald Duck), or are the highs or low audio frequencies not coming through?
Does changing the microphone help at all?
I'd also be concerned that the problem appears less problematical when you turn the RF power down. To me that suggests RF coming back to the radio from your antenna system in the form of common mode currents. Are you running an end fed antenna system? Do you have any sort of common mode choke system employed?
It obviously can be difficult making suggestions from afar so any further information you can provide will help others to help you.
Let's hope you can get to the bottom of the problem and maybe an easy solution presents itself.
All the best, Victor
SangueG likes this post
teapot Contributor
Call Sign : 26-CT-4484 Posts : 88 Times Thanked : 2 Join date : 2021-10-17 QTH or Location : Torquay Equipment Used : cobra 148 glt dx starlker9 fdx, icom 706 mk1
Subject: Re: need help Sun Aug 07, 2022 6:59 am
thanks victor from what i was told it sounded very stretchy like a badly tune old 80s fm cb. i am going to order a new mic today. its the same on all modes. the antenna has an swr of 1.2 on 11 meters. dave
Alan Pilot Major contributor
Call Sign : 163-CT-220...MW7TTA Posts : 2510 Times Thanked : 69 Join date : 2019-11-19 QTH or Location : Anglesey North Wales Equipment Used : Yaesu FT-991A,,Yaesu FTDX-10,,Icom ic-7300,,Anytone AT-D878UV PLUS",,LINCOLN II+. Age : 150
Subject: Re: need help Sun Aug 07, 2022 7:08 am
Have you done a factory reset. It might help to have everything set at default. As said do you have any choke's in place and what antenna is it ?.
SangueG likes this post
teapot Contributor
Call Sign : 26-CT-4484 Posts : 88 Times Thanked : 2 Join date : 2021-10-17 QTH or Location : Torquay Equipment Used : cobra 148 glt dx starlker9 fdx, icom 706 mk1
Subject: Re: need help Sun Aug 07, 2022 7:15 am
the antenna is a stinger mag mount on my car as mom wont let me put anything up i her garden the antenna works fine on with my 6900 and 9900 i have not done a reset no, how do you do that? dave
Alan Pilot Major contributor
Call Sign : 163-CT-220...MW7TTA Posts : 2510 Times Thanked : 69 Join date : 2019-11-19 QTH or Location : Anglesey North Wales Equipment Used : Yaesu FT-991A,,Yaesu FTDX-10,,Icom ic-7300,,Anytone AT-D878UV PLUS",,LINCOLN II+. Age : 150
Subject: Re: need help Sun Aug 07, 2022 7:23 am
Google should show you how to reset it. Just a case of holding down a button and powering it on at the same time. Did you get the manual with it that will also tell you.
SangueG Major contributor
Call Sign : 26-CT-3971 / 2E0LMI Posts : 1129 Times Thanked : 68 Join date : 2021-01-30 QTH or Location : Cirencester, Gloucestershire Equipment Used : Little radios, home-made antennas
Subject: Re: need help Sun Aug 07, 2022 7:28 am
Just throwing a quick thought on it to you; has someone told you your modulation sounds like that or have you found this yourself by checking it on a radio in the same room?
Just asking, as if the latter then I get similar results. When I use my old DX-300 to check what I sound like I have to turn the power down to lowest setting on the transceiver I am checking and turn the RF gain back and flick on the attenuator on the DX-300, otherwise the old thing gets overloaded and the audio sounds very muffled and suppressed.
Re Victor's thoughts on common mode, if you have a dummy load you could try transmitting into that and see what results you get. Should transmit enough RF if your receive radio is in the same room. If all good then, you know it's antenna / feeder issue.
Victor likes this post
teapot Contributor
Call Sign : 26-CT-4484 Posts : 88 Times Thanked : 2 Join date : 2021-10-17 QTH or Location : Torquay Equipment Used : cobra 148 glt dx starlker9 fdx, icom 706 mk1
Subject: Re: need help Sun Aug 07, 2022 7:34 am
was told by a couple of local stations who i have spoken to a few times on my other radios so do trust them dave
Ivy Mike Major contributor
Call Sign : 26CT4113/G1HWY Posts : 454 Times Thanked : 12 Join date : 2021-05-16 QTH or Location : IO90uv Equipment Used : ICOM radios/antenna farm Age : 68
Subject: Re: need help Sun Aug 07, 2022 8:01 am
Victor is most likely correct, RF feeding back causing distorted audio, your very close to the source so may be expected.
teapot Contributor
Call Sign : 26-CT-4484 Posts : 88 Times Thanked : 2 Join date : 2021-10-17 QTH or Location : Torquay Equipment Used : cobra 148 glt dx starlker9 fdx, icom 706 mk1
Subject: Re: need help Sun Aug 07, 2022 8:43 am
i have just tried it on am and it works great, messed about with the mic lead while chatting and it just dropped out so it needs a new mic and lead when they come ill make sure my car is further away from my radio so the antenna is further away and hopefully that will cure it many thanks to you all Dave
teapot Contributor
Call Sign : 26-CT-4484 Posts : 88 Times Thanked : 2 Join date : 2021-10-17 QTH or Location : Torquay Equipment Used : cobra 148 glt dx starlker9 fdx, icom 706 mk1
Subject: Re: need help Sun Aug 28, 2022 3:47 pm
just a quick update on my problem it was my psu it was not working correctly so not pushing enough power to run the radio brought another and new mic and it is working as it should so thanks for all your help in this matter. Dave
MikeInCzechRep likes this post
Alan Pilot Major contributor
Call Sign : 163-CT-220...MW7TTA Posts : 2510 Times Thanked : 69 Join date : 2019-11-19 QTH or Location : Anglesey North Wales Equipment Used : Yaesu FT-991A,,Yaesu FTDX-10,,Icom ic-7300,,Anytone AT-D878UV PLUS",,LINCOLN II+. Age : 150
Subject: Re: need help Sun Aug 28, 2022 4:23 pm
Glad you got it sorted out.
teapot Contributor
Call Sign : 26-CT-4484 Posts : 88 Times Thanked : 2 Join date : 2021-10-17 QTH or Location : Torquay Equipment Used : cobra 148 glt dx starlker9 fdx, icom 706 mk1
Subject: Re: need help Sun Aug 28, 2022 4:31 pm
thanks Alan in fact it was a guy from the moors that come up with idea and i thought that I would give it ago and thank god it worked dave
Victor CT Directors
Call Sign : 26-CT-3228 / M7VIC Posts : 5778 Times Thanked : 352 Join date : 2019-11-10 QTH or Location : Bedford Equipment Used : Various
Subject: Re: need help Mon Aug 29, 2022 6:16 am
Glad you're all sorted now Dave.
As I mentioned it can be difficult sorting these type of problems especially with advice from afar. I thought we'd already covered power supply issues with what was mentioned on your first posting (hence RF feedback problems suggested as another alternative) but pleased that everything is now resolved.
Enjoy your radio and thanks for coming back to update everyone that offered assistance.