Topics

Poor quality SRF59s - can they be aligned ?


Gary DeBock
 

To Dave Kenny, Huelbe Garcia and Others,
 
     Concerning the Chinese factory alignments of the recent SRF-59 units, it is typically not accurate, and new units are usually not as sensitive as possible.  After performing 38 SRF-59 alignments for others in North America,  I have discovered that the smaller coil on the loopstick is almost never in the optimum position to peak a 600 kHz signal, and this simple adjustment can make a huge difference in SRF-59 sensitivity.
 
     The disassembly of the SRF-59 is a little tricky, and the dial reassembly causes problems for many people.  For someone in North America, I can easily align the SRF-59's (or SRF-39FP's) for free (with return postage paid), and would be happy to do this for anyone in the world, if you can send the units to me here in the USA.  Completely defective units are rare, with the most common problem being a noisy tuning capacitor which induces static whenever the frequency is changed.  This happens only on about 10% of the units, but it is incurable without an impractical tuner replacement.
 
                                                                                                 73,  Gary DeBock
 
                                                                                                 Original "Ultra-fanatic"  




Create a Home Theater Like the Pros. Watch the video on AOL Home.


bdxcuk <bdxc@...>
 

I've got two SRF59s but both are defective. One has a dial that only
tunes up to about 1550 kHz on MW and to about 107 MHz on FM.

The other is completely deaf and even reception of local AM stations
is poor and noisy.

It seems that quality control on these radios is not good.
Unfortunately I bought them via eBay so can't return them.

Does anyone know if these radios can be aligned to improve
performance? Any details would be welcome.

73s Dave Kenny
UK


Gary DeBock
 

Hi Again Huelbe,
 
     Please don't worry about English here-- if I had to write in Portuguese, it would be a true disaster.
 
     The SRF-59 (and SRF-39FP) loopstick does have both a larger and smaller coil, but only the smaller (movable) coil is necessary for alignment adjustment.  The larger (fixed) coil is glued in place, and is not designed to be moved at all.
 
     For alignment, remove all wax bonding the smaller coil to the ferrite bar, and tune in a signal around 600 kHz on the low end of the band.  Using a wooden probe, move the smaller coil about 5 mm either way from its original position, to find the spot of maximum signal reception of the 600 kHz station.  After finding this spot, either glue the coil in this position (if it has corrected the radio's sensitivity problem) or proceed to adjust the upper left trimmer capacitor on the tuner to peak a 1400 kHz signal (for full alignment).  My own alignment procedure is to peak both adjustments repeatedly, until no further improvement is gained.  Then, I glue the loopstick's smaller coil in the peak position, and reassemble the radio.
 
     The alignment procedure usually gives a big boost in SRF-59 sensitivity, and should be considered by all owners to ensure maximum DX performance.
 
                                                                                     73,  Gary DeBock




Create a Home Theater Like the Pros. Watch the video on AOL Home.


huelbe_garcia@...
 

Hi Dave, good day.

I also bought a SRF-59 (from a chinese seller) at eBay with a few problems.

The AM receiver had poor selectivity and images/mirroring about 100khz apart
from strong stations. The FM receiver started at 81MHz (I can hear the audio
from TV channel 5).

In my case, alignment by ear of the AM sector made the receiver work nice
again.

The service and alignment manual for SRF-PSY03 (it's identical to SRF-59)
was made available by our ULR fans at www.dxer.ca, under menu Ultra-light
file area.

For alignment procedure, you will have to move coil L5 over the ferrite rod.
As it has a kind of glue/wax, I am not sure what is the best way to remove
it. John Bryant (at the list-next-door UltraLightHotRodding) used a hair
dryer.

Good luck!

--hg

----- Original Message -----
From: "bdxcuk" <bdxc@...>
To: <ultralightdx@...>
Sent: Friday, March 28, 2008 11:04 AM
Subject: [ultralightdx] Poor quality SRF59s - can they be aligned ?


I've got two SRF59s but both are defective. One has a dial that only
tunes up to about 1550 kHz on MW and to about 107 MHz on FM.

The other is completely deaf and even reception of local AM stations
is poor and noisy.

It seems that quality control on these radios is not good.
Unfortunately I bought them via eBay so can't return them.

Does anyone know if these radios can be aligned to improve
performance? Any details would be welcome.

73s Dave Kenny
UK


------------------------------------

Yahoo! Groups Links


huelbe_garcia@...
 

Hi Gary,

thank you for your prompt reply your offer to make alignment for other
ULR-fans.

In your experience, is it enough to change the position of the smaller coil?
Or is it needed to also work at the bigger coil?

I found the smaller coil very easy to move around. However, I have no idea
how to move the bigger coil over the ferrite core. I think some soldering
work is necessary.

(just to make clear to all friends in this list: SRF59s have one ferrite rod
with two coils - the one to the left has almost two-times more wire than the
one to the right. Bryant and Gary, however, concluded it is electrically one
coil with taps.)

Huelbe

P.S.: I really apologize if my english does not 'sound' well. As I have
never lived abroad, perhaps my text may have expressions and grammar
constructions that are not-polite, rude or uncorteous. This is not intended.
:)

----- Original Message -----
From: @dxergary
Sent: Friday, March 28, 2008 12:34 PM
Subject: Re: [ultralightdx] Poor quality SRF59s - can they be aligned ?


To Dave Kenny, Huelbe Garcia and Others,

Concerning the Chinese factory alignments of the recent SRF-59 units,
it is typically not accurate, and new units are usually not as sensitive as
possible. After performing 38 SRF-59 alignments for others in North
America, I have discovered that the smaller coil on the loopstick is almost
never in the optimum position to peak a 600 kHz signal, and this simple
adjustment can make a huge difference in SRF-59 sensitivity.


73, Gary DeBock


Original "Ultra-fanatic"


slowfly55
 

Hi Dave and others

I have two SRF-59, one normal and one "Made in China", probably from
the same ebay-seller as you mention. After a little alignment of
the chinese I cannot say, which of the two is better. Performance,
e.i. sensitivity and selectivity of the China made SRF-59 is not
inferior.
Was I lucky or is it only a factory alignment problem?

Peter


Michael Slattery
 

On Fri, 28 Mar 2008 14:09:29 EDT, you wrote:

The alignment procedure usually gives a big boost in SRF-59
sensitivity, and should be considered by all owners to ensure maximum DX performance.
Greetings all from the city of Sheffield, Yorkshire, in the north
central part of England, UK!

So far I have had three examples of the SRF-59. All have the static
noise problem when tuning. All suffered the ferrite coil adjustment
being badly misaligned. As Gary says a big boost in overall
sensitivity and nulling is gained by alignment. Well worth doing.

The simplest way I've found to free the coil for alignment is to first
extricate the PCB from the case. For the protection of the components,
wrap some cardboard around the PCB leaving just the ferrite aerial and
the PCB area underneath it exposed. Then play some warm air from a
hair drier or carefully from a heat gun onto the exposed area of PCB
under the rod. Watch the condition of the wax noting when it has just
become molten at the point where it is in contact with the PCB. Try to
gently slide the coil side to side and when free simultaneously
withdraw the PCB from the warming airflow. Keep moving the coil from
side to side whilst the wax solidifies. Once the wax has solidified
the coil should remain free. It will look like there is a crack in the
wax between the coil and the PCB. Alignment can then commence.

Once alignment is complete, rewrap the PCB in the cardboard, reheat
the PCB under and around the ferrite aerial to remelt the wax. Tilt
the PCB so as to encourage the wax to bridge the coil and the PCB
until it appears fused as before.

I would encourage anyone to have ago at this. There is little to go
wrong as long as care is taken.

--
Michael G8PNX
wildbear@...