improving sensitivity: DX-398
 

just aquired a used radioshack DX 398--works well except the sensitivty is
low (sounds like an attenuator is switched in!!)...are there things to
check/modifications etc to improve the sensitivity of this radio?

i am running the attenuator knob at the full gain posiiton.

radio wld be fantastic IF I could improve its sensitivity/gain. As stands--my
SONY 7600/YachtBoy 400 etc absolutely blow it away..i dont think this is a
normal situation, so i suspect the dx 398 has a problem.

thanx for all suggestions/links to web sites dealing with this issue.

ed s

This may sound like a stupid question but...
You DO have it turned ON all the way and not OFF? COUNTER-CLOCKWISE is on
full...



"Bunia3" wrote in message
...

just aquired a used radioshack DX 398--works well except the sensitivty
is
low (sounds like an attenuator is switched in!!)...are there things to
check/modifications etc to improve the sensitivity of this radio?

i am running the attenuator knob at the full gain posiiton.

radio wld be fantastic IF I could improve its sensitivity/gain. As
stands--my
SONY 7600/YachtBoy 400 etc absolutely blow it away..i dont think this is a
normal situation, so i suspect the dx 398 has a problem.

thanx for all suggestions/links to web sites dealing with this issue.

ed s

It also 'clicks' to the full sensitive setting.

Ken

"Jim Hackett" wrote in message
ink.net...
This may sound like a stupid question but...
You DO have it turned ON all the way and not OFF? COUNTER-CLOCKWISE is
on
full...



"Bunia3" wrote in message
...

just aquired a used radioshack DX 398--works well except the
sensitivty
is
low (sounds like an attenuator is switched in!!)...are there things to
check/modifications etc to improve the sensitivity of this radio?

i am running the attenuator knob at the full gain posiiton.

radio wld be fantastic IF I could improve its sensitivity/gain. As
stands--my
SONY 7600/YachtBoy 400 etc absolutely blow it away..i dont think this is
a
normal situation, so i suspect the dx 398 has a problem.

thanx for all suggestions/links to web sites dealing with this issue.

ed s

Does anyone know what device functions as the first RF amp in this radio?
Most likely some kind of FET...That would be a good place to check if you
are convinced the sensitivity is down. Some models of radios had FET RF
amps that were susceptible to static damage.



"Bunia3" wrote in message
...

just aquired a used radioshack DX 398--works well except the sensitivty
is
low (sounds like an attenuator is switched in!!)...are there things to
check/modifications etc to improve the sensitivity of this radio?

i am running the attenuator knob at the full gain posiiton.

radio wld be fantastic IF I could improve its sensitivity/gain. As
stands--my
SONY 7600/YachtBoy 400 etc absolutely blow it away..i dont think this is a
normal situation, so i suspect the dx 398 has a problem.

thanx for all suggestions/links to web sites dealing with this issue.

ed s

"Bunia3" wrote in message
...

just aquired a used radioshack DX 398--works well except the
sensitivty is
low (sounds like an attenuator is switched in!!)...are there things
to
check/modifications etc to improve the sensitivity of this radio?

i am running the attenuator knob at the full gain posiiton.

radio wld be fantastic IF I could improve its sensitivity/gain. As
stands--my
SONY 7600/YachtBoy 400 etc absolutely blow it away..i dont think
this is a
normal situation, so i suspect the dx 398 has a problem.

thanx for all suggestions/links to web sites dealing with this
issue.


IMO, there's something wrong with the radio if those other two
"absolutely blow it away." Regardless of the merits of the three--and
the standard knock on the 398 is an alleged lack of sensitivity on the
whip--there should not be -that- big a difference. These guys
reportedly do a great job and you may get some ideas about mods he
http://www.radiolabs.com/products/re...s/super909.php

I would check the Yahoo 398/909 group as well. As I remember there's
a lot of discussion of mods there as well.

There may not be anything wrong with yours. The 398/909 is pretty
deaf off the whip. Try an external antenna of even moderate length,
20 ft or so into the external antenna jack. You should find that the
radio really comes alive. If not, then you have a problem.

The 398/909 is super with a short external wire. This is why I think
it is great mini-desk top radio but not so hot as a travel portable.
Also, the extremely short battery life on this radio makes it a poor
choice as a portable.

Feed it a little wire and an AC adapter and you got a great set up

Feed it a little wire and an AC adapter and you got a great set up

Shoot, I run a at least a 120ft.wire sloper (rf free environment) on it and
it's just fine.

~*~*Monitoring The AirWaves~*~
*****GO BEARCATS*****
Hammarlund HQ129X /Heathkit Q Multiplier
Hammarlund HQ140X
Multiple GE P-780's(GREAT BCB Radios)
RCA Victor *Strato- World*
RCA Victor RJC77W-K(Walnut Grain)
1942 Zenith Wave Magnet 6G 601M
Cathedral/ Ross#2311/Rhapsody-MultiBand
DX100/394/398/399/402
OMGS Transistor Eight/Realistic 12-1451
Henry Kloss Model One/Bell+Howell
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Alpha Delta DX Sloper 57ft.
600ft. 12AWG. (non-terminated)
120ft. 12 AWG Sloper
2 Radio Shack Loop Antennas
Radio Shack Amplified Antenna
30X30 DiamondLoop(six section 830pf Cap)
* Diamond Loop mounted to Lazy Susan TurnTable*
*21/2X2ft.FiveSpoked~Penta-Loop~PancakeLoop*

yeah. The little wound transformer transplant from Frank C. fixes the whip
impedence matching problem and makes the whip real sensitive. There is also a
blocking transister you can remove to increase all AM sensitivity, including mw
reception. It won't resist interfering FM bleeds into the SW band as well
though.I have both mods on one 398 and just the transformer mod on the other. I
tend to like just the implant the best. You can find these mods by searching.
....Hindsight Band

Sangeans in general are known for this. They work better than most though
with an external antenna.

"Bunia3" wrote in message
...

just aquired a used radioshack DX 398--works well except the sensitivty
is
low (sounds like an attenuator is switched in!!)...are there things to
check/modifications etc to improve the sensitivity of this radio?

i am running the attenuator knob at the full gain posiiton.

radio wld be fantastic IF I could improve its sensitivity/gain. As
stands--my
SONY 7600/YachtBoy 400 etc absolutely blow it away..i dont think this is a
normal situation, so i suspect the dx 398 has a problem.

thanx for all suggestions/links to web sites dealing with this issue.

ed s

Rick W 999 wrote:

yeah. The little wound transformer transplant from Frank C. fixes the whip
impedence matching problem and makes the whip real sensitive. There is also a
blocking transister you can remove to increase all AM sensitivity, including mw
reception. It won't resist interfering FM bleeds into the SW band as well
though.I have both mods on one 398 and just the transformer mod on the other. I
tend to like just the implant the best. You can find these mods by searching.
...Hindsight Band

I did the R43 resistor mod' (removal) and the homemade impedance
matching transformer for the whip, in that order. If I had known how
well the transformer works, I wouldn't have bothered removing R43 too.
Someday I'll put it back.


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