FM-100 Modifications

[djgeoffb]

I am a new owner of a Ramsey FM-100 (the export version, incidentally) and I've heard a lot about "fixes" for this model. I'd like some guidance from the technicians who designed this unit.

1. It has been suggested at http://people.mw.mediaone.net/laser95x/page2.html that replacing R8 with a higher value will improve the bass response and dynamic range.

2. A review at http://www.geocities.com/Area51/Nebu...100_report.txt suggests several modifications. I'm mainly interested in:

a. Replacing C13 with a 300pf silver mica to let less PLL "hash" get back into the modulated signal.

b. Adding a 10uf tantalum bypass capacitor to the junction of R8 and R7 to minimize "bass rumbles"

c. Placing a 10k ohm resistor in parallel with a .0022 uf capacitor connected
to (in parallel with or replacing) R34 (and the same for R72) to "brighten" the audio signal

3. The reset fix found at http://www.geocities.com/Area51/Nebu.../fm100-fix.txt

Of course my unit is only used into a dummy load, so as to not violate any FCC rules.

Thanks,

Geoff

[bigmack]

<BLOCKQUOTE>quote:</font><HR>Originally posted by DJ_Geoff_B:
I am a new owner of a Ramsey FM-100 (the export version, incidentally) and I've heard a lot about "fixes" for this model. I'd like some guidance from the technicians who designed this unit.

1. It has been suggested at http://people.mw.mediaone.net/laser95x/page2.html that replacing R8 with a higher value will improve the bass response and dynamic range.

2. A review at http://www.geocities.com/Area51/Nebu...100_report.txt suggests several modifications. I'm mainly interested in:

a. Replacing C13 with a 300pf silver mica to let less PLL "hash" get back into the modulated signal.

b. Adding a 10uf tantalum bypass capacitor to the junction of R8 and R7 to minimize "bass rumbles"

c. Placing a 10k ohm resistor in parallel with a .0022 uf capacitor connected
to (in parallel with or replacing) R34 (and the same for R72) to "brighten" the audio signal

3. The reset fix found at http://www.geocities.com/Area51/Nebu.../fm100-fix.txt

Of course my unit is only used into a dummy load, so as to not violate any FCC rules.

Thanks,

Geoff<HR></BLOCKQUOTE>

[bigmack]

Hello, First, sorry for the previous blank message.
I have tried the first mod mentioned in Geoff's post and it makes an incredible difference in the sound quality of the FM-100.
I can't speak to the other mods however.
The only caution would be if the unit is still under warranty
modifying the unit might invalidate it.

[tremendo]

Geoff or Bigmack or anyone -

Where can I get info on that sound quality improvement mod for the FM100? That link is no longer valid. Also, my understanding is that the unit has 100% the same circuits as 5 years ago, so all mods would still be valid.

thanks!

Tremendo

[ March 11, 2002: Message edited by: tremendo ]

[bigmack]

Try: http://people.mw.mediaone.net/laser95x/page2.htm

[tremendo]

OK, I did the mod 2. My range went upto 45 miles with awesome 20-20 sound. No, not really, but it was very easy and I believe gives much better bass, as well as presence. There are no details needed of how to do it, I just changed the R8 from a 10k 1/4 watt to a 47k 1/4 watt. I had to buy a 5 pack of resisters, setting me back a whole 67 cents (13 cents each).

I highly recommend it to anyone with an FM100. By the way, this was a great plus of having this board, I never would have had any clue if what to do.

[djgeoffb]

Tremendo,

Send me one of those extra resistors. I haven't made the mod yet!

[tremendo]

Geoff, if you're serious, send me you address. It's not the $, but thpain in getting them. I called 2 different Radio Shacks that said they had them, but when I got there, no dice. My 3rd one had them.

Tremendo