Your MFJ-1708B-T/R Switch Experiences

General discussions
Ruben_NB4R
Posts: 10
Joined: Thu Jan 10, 2019 11:52 pm

Your MFJ-1708B-T/R Switch Experiences

Postby Ruben_NB4R » Mon Jan 14, 2019 6:01 pm

I have an new RSP1A and an MFJ-1708B-SDR. I have read all I can find in this forum pertaining to this matched pair, but am not seeing the information I'm needing. I would like to hear from anyone that is using the RSP1A with the MFJ-1708B-SDR without having made any other modifications. I've read about diode protection and cascading relays off the mic PTT contacts. The MFJ-1708 is supposed to ground the input to the RSP1A when the switch is in transmit mode.

I plan on using the pair on a Yaesu FT1000-MP and an Ameritron AL80-b amp. I will be inserting the switch between the transceiver and the amp. I do like the idea of the cascading relay idea and just might implement that idea. I also read where some have gained receiver protection by putting the receiver in an aluminium box. I don't know why the SDRPlay don't make this standard practice if it is so needed. I am open to suggestions and ideas, but I would really like to hear what your experiences are if you Use the RSP1A/MFJ1708 pair without mods. Thank you very much!
73
Ruben_NB4R
Last edited by Ruben_NB4R on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

JohnAE5X
Posts: 12
Joined: Fri May 11, 2018 6:50 pm

Re: Your MFJ-1708B-T/R Switch Experiences

Postby JohnAE5X » Sun Jan 20, 2019 1:23 pm

It is not needed in many applications, such as SWLing, ADS-B monitoring, etc. For those/us users, an aluminum box would be an added and unnecessary expense. I'm happy to have the option of buying just as much product as I need and no more.

John AE5X
_______________________________________

"I also read where some have gained receiver protection by putting the receiver in an aluminum box. I don't know why the SDRPlay don't make this standard practice if it is so needed."

Reason: No reason

ON5HB
Posts: 124
Joined: Sat Dec 29, 2018 1:07 pm
Location: Heppen - Belgium
Contact:

Re: Your MFJ-1708B-T/R Switch Experiences

Postby ON5HB » Mon Jan 21, 2019 5:30 pm

First of all the inside of the RSP1A is sprayed with a metal paint as many reviews have pointed out, also they state it's effective.

I have ordered the MFJ1708B myself, but currently I'm running the Icom 7300 with an Acom 1010 pretty close to it, it's not disconnected from my Inverted-L 160m antenna (at less then 2m distance 90 degrees angled) and only protected with a NoElec 125MHz upconverter.

Both have extra protection, yes the RSP1A does also.

I can load my G5RV up to 1 KWpeak and nothing happens to the RSP1A except being overloaded in the waterfall.

The MFJ effectively shortens the SDR port when in TX or being powerless as you can see in the schematics.
It's also TX sensitive, so even if you don't connect PTT it will still switch.

There is no need for a metalbox as it's protected with paint at the inside and it will not break when you TX.

Do not worry, nothing will happen to the RSP1A.
I abuse the hell out of the 3 I have, so far nothing happened and my websdr users love it when they see me making contacts, at first it scares the hell out of them thinking my websdr is falling apart :lol:

Do not do what I do on purpose! But they do not break that easy.

Reason: No reason
Greetings,

Bas - ON5HB

vk3alb
Posts: 36
Joined: Sat Jul 01, 2017 11:43 pm

Re: Your MFJ-1708B-T/R Switch Experiences

Postby vk3alb » Mon Jan 21, 2019 8:55 pm

Ruben_NB4R wrote: I don't know why the SDRPlay don't make this standard practice if it is so needed.
Ruben_NB4R


The RSP2pro comes in a metal box but also comes at a price. As has already been mentioned not everyone needs such heavy shielding.

Reason: No reason
Lou
VK3ALB

SV1RXI
Posts: 1
Joined: Thu Mar 14, 2019 3:29 pm

Re: Your MFJ-1708B-T/R Switch Experiences

Postby SV1RXI » Sun Mar 17, 2019 12:13 pm

Hi team. I also read some posts about the mfj1708b sdr s. I have now the 891 and just 2 days ago i buy the rsp1a. The first version of the mfj i read many complains about high swr. Also see the mfj is one way road. There is also one dx Engineering product RTR-2 but is very expensive and i don't know if it needs others equipment to work for. Also maybe i use the 7300 with the mfj and share the same antenna, bust most i use the yaesu 891. Any worries or other thing to look and some of you experienced with 1708b sdr s.? Thanks
Last edited by SV1RXI on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason


Return to “General”

Who is online

Users browsing this forum: No registered users and 10 guests