Radio Shack SWR meter

[Paul Lee]

I just posted a question on the RS SWR meter and the thread
dissapeared.

Here is my question again. Is there some way of modifying
the Radio Shack SWR meter (27MHZ) to make it work in the
aircraft radio range (120MHZ)?

I am not asking if I should use it or not but what circuit
modification can be done so it centers in the aircraft VHF
frequencies. SWR circuitry is usually simple and the RS
SWR meter already's got the meter and knobs. Anybody's
done that already?

[Darrel Toepfer]

Paul Lee wrote:
> I just posted a question on the RS SWR meter and the thread
> dissapeared.
>
> Here is my question again. Is there some way of modifying
> the Radio Shack SWR meter (27MHZ) to make it work in the
> aircraft radio range (120MHZ)?
>
> I am not asking if I should use it or not but what circuit
> modification can be done so it centers in the aircraft VHF
> frequencies. SWR circuitry is usually simple and the RS
> SWR meter already's got the meter and knobs. Anybody's
> done that already?

Since you are hung up on RadioShack:

Vectronics VHF/UHF SWR / WattMeter-BNC
$89.95 Catalog #: 940-0595
Model: VEC732B RSU #: 99400595

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F008%5F009%5F001%5F001&product%5Fid=940%2D0595

This meter simultaneously measures forward and reflected power and SWR
in the frequency range. It also simultaneously displays these readouts
on their dual movement meter systems. The meters' true-shielded
directional couplers ensure the accuracy of their readings, and the
backlit displays provide peak or average power readouts. Includes BNC
connector on back. 100 to 500MHz frequency range programmed in three
switched steps. Range settings: 300/3000W. (Mfr. Warranty: one-year.
Size: 3.5x5.3x5.75" (HWD). Weight: 1.2 lbs.)

[Rob Turk]

"Darrel Toepfer" > wrote in message
. ..
>
> Since you are hung up on RadioShack:
>
> Vectronics VHF/UHF SWR / WattMeter-BNC
> $89.95 Catalog #: 940-0595
> Model: VEC732B RSU #: 99400595
>
>
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F008%5F009%5F001%5F001&product%5Fid=940%2D0595
>
> Range settings: 300/3000W.

This may not be what he wants. Airband radio's have an output of only 4 -
10W. That may not be enough to get full-scale reference on the SWR meter,
making the SWR reading unreliable.

Rob

[Darrel Toepfer]

Rob Turk wrote:

>>Range settings: 300/3000W.
>
> This may not be what he wants. Airband radio's have an output of only 4 -
> 10W. That may not be enough to get full-scale reference on the SWR meter,
> making the SWR reading unreliable.

Point taken, but reflected power measurements are always on the low
side. This one would do as well, has lots more features, but with a
price penality and loss of forward power measurement:

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F008%5F009%5F001%5F005&product%5Fid=940%2D0683

[Howard Eisenhauer]

Paul, it will depend on your specific model of meter. If it's the
kind that reads SWR directly & has a "cal" knob for the meter no mods
are needed, just set your meter the same as you would for a CB, the
SWR measurment will be right.

If it's the "forward & reverse power" variety there should be trim
pot adjustments inside the case to adjust the meter to read watts
correctly but you'll need to lay your hands on an accurate meter (Bird
43 w/correct slugs recommended) for that frequency range to compare
yours against. Just hook them in series & adjust yours to read the
same as the "good" one.

Just for comparison, I've got a 30 year old RS CB
power-modulation-vswr combo meter that reads pretty much correctly at
148 mhz, so if yours is off it probably won't be by much.

Have fun, don't let the smoke out :).

Howard.

On 31 May 2004 22:31:31 -0700, (Paul Lee)
wrote:

>I just posted a question on the RS SWR meter and the thread
>dissapeared.
>
>Here is my question again. Is there some way of modifying
>the Radio Shack SWR meter (27MHZ) to make it work in the
>aircraft radio range (120MHZ)?
>
>I am not asking if I should use it or not but what circuit
>modification can be done so it centers in the aircraft VHF
>frequencies. SWR circuitry is usually simple and the RS
>SWR meter already's got the meter and knobs. Anybody's
>done that already?

[G. Burkhart]

"Darrel Toepfer" > wrote in message
...
> Rob Turk wrote:
>
> >>Range settings: 300/3000W.
> >
> > This may not be what he wants. Airband radio's have an output of only
4 -
> > 10W. That may not be enough to get full-scale reference on the SWR
meter,
> > making the SWR reading unreliable.
>
> Point taken, but reflected power measurements are always on the low
> side. This one would do as well, has lots more features, but with a
> price penality and loss of forward power measurement:
>
>
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F008%5F009%5F001%5F005&product%5Fid=940%2D0683

Same thing here on eBay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=48701&item=5702730845&rd=1&ssPageName=WDVW

[Paul Lee]

"Rob Turk" > wrote in message >...
> "Darrel Toepfer" > wrote in message
> . ..
> >
> > Since you are hung up on RadioShack:
> >
> > Vectronics VHF/UHF SWR / WattMeter-BNC
> > $89.95 Catalog #: 940-0595
> > Model: VEC732B RSU #: 99400595
> >
> >
> http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F008%5F009%5F001%5F001&product%5Fid=940%2D0595
> >
> > Range settings: 300/3000W.
>
> This may not be what he wants. Airband radio's have an output of only 4 -
> 10W. That may not be enough to get full-scale reference on the SWR meter,
> making the SWR reading unreliable.
>
> Rob

I think that is a misprint. It should be 30/300W. I just ordered the same thing
from another distributor and it said 30/300W - and about $10 cheaper.