How do i increase the frequency range of a radio ( receiver )

Thread Starter

Just me1

Joined Sep 3, 2017
59
hi reader ( s )

i have searched the internet for days, and no results, i simply want to be able to listen to frequencies above 1700khz ( long wave ), but i cant get that high.
i learned this could be done by using an antenna,( with some tuning components ?).
so how do i design an antenna that can enable my radio to receive those frequencies ?

thanks in advance,

just me1
 

Reloadron

Joined Jan 15, 2015
4,587
There is much more to doing this than antenna modifications. Seriously your best option is to find a receiver capable of receiving the frequency range you are interested in. Before you can modify anything existing you would need a complete schematic of what you already have.

Ron
 

Motanache

Joined Mar 2, 2015
481
I can help you but without schematic can not be done.

Put at least one picture with the PCB of the radio and write which are the main integrates.

At AM reception, reception frequency is given by LC oscillating circuit (reception).

For a smaller reception frequency, roll several extra turns on the coil.
For a higher reception frequency, you can unroll turns from coil.

There is also a frequency converter that is placed on the antenna.
It's just an example: it's not your case.
https://www.ebay.com/p/Frequency-Converter-Antenna-Radio-FM-Band-Expander-88-108mhz-for-Japanese-Car-ES/769436328?iid=232304697974

And there's also a simple schematic for that.
I knew him from older magazines
 

DickCappels

Joined Aug 21, 2008
5,938
Back in the old days to get just above the AM band we just adjusted the trim capacitors on the tuning capacitor for the LO and mixer. If you have a superhetrodyne receiver you can try that approach.

Another way is to use a tuning adapter or converter similar to the one Motanache mentioned, that will mix out-of-band signals down into the tuning range of your receiver. A 700 kHz local oscillator would mix 1700 kHz down to 1 mHz. Searchng the internet with the search term "SA612" should give you lots of ideas.
 

Thread Starter

Just me1

Joined Sep 3, 2017
59
Back in the old days to get just above the AM band we just adjusted the trim capacitors on the tuning capacitor for the LO and mixer. If you have a superhetrodyne receiver you can try that approach.

Another way is to use a tuning adapter or converter similar to the one Motanache mentioned, that will mix out-of-band signals down into the tuning range of your receiver. A 700 kHz local oscillator would mix 1700 kHz down to 1 mHz. Searchng the internet with the search term "SA612" should give you lots of ideas.
do i have to modify the main board for any of these options?
 

Reloadron

Joined Jan 15, 2015
4,587
I suggest you read this article as you may find it of some use. It addresses one of the methods Dick mentions. Again, without a schematic of what you actually have it is really difficult to make suggestions. It would also help if you did a little study to understand how a basic AM Broadcast Band actually is tuned and works.

Ron
 

DickCappels

Joined Aug 21, 2008
5,938
do i have to modify the main board for any of these options?
To retune the local oscillator and mixer front end you just need a screwdriver if your radio is old enough to have the trimmer capacitors.

The second solution, that of making a down-converter requires making an external circuit assembly.

The Software Defined Radio that to which Bertus linked in Post #7 is probably the best solution. You can get SDR dognles inexpensively via the internet (eBay, Amazon, www.alibaba.com, etc.) just make sure that the one you get can tune to the frequency in which you are interested -it seems some of them are restricted to broadcast bands.
 

ian field

Joined Oct 27, 2012
6,540
do i have to modify the main board for any of these options?
Dickcappels nailed it with the converter idea, its just an oscillator that radiates a low level signal to beat with your wanted signal - you arrange for sum or difference heterodyne frequency to land where your radio can find it. You don't even need to take the back off the radio.

With a TRF or regen radio; you need only take a few turns off the tuning coil to increase the frequency. Most sets are super heterodyne that have a local oscillator which would also need adjusting.

If its a not very crowded band you're after, you might get away with getting rid of the tuning tank circuit altogether. then you only have to adjust the local oscillator to shift the wanted signal to the intermediate frequency.

Throwing out the loopstick doesn't help gain much - I'd add a JFET source follower input stage and a short wire whip antenna. The loopstick pick up coil usually bridges from the bias resistors to the base of the mixer/oscillator transistor - you have to restore its DC path after ripping out the loopstick.
 
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