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Author Topic: Moding a Regency RH 256 B VHF into 2meter?  (Read 4041 times)
KD0ILS
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Posts: 7




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« on: May 09, 2011, 11:07:30 AM »

I have a Regency RH 256 B radio, it works just fine, however i have no use for a radio in the business band.  I can tune it to local public works and emergency services and it can weakly receive them.  It transmits from 150-162mHz with 25w output.  The radio i have is the "Band B" radio, there is also a "Band A" radio that transmits from 134-150mHz and a "Band C" version that transmits from 162-174mHz.  I was wondering if anyone knew how to change the "Bands" or of any mods to transmit on the 2meter band with this radio.  Any help is Greatly appreciated!
73's
Peter 
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KF7PSM
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Posts: 1




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« Reply #1 on: June 21, 2011, 08:36:20 AM »

I have succesfully done this mod and it works great!!  Smiley The radio was actually designed for 3 bands and one of the bands was 134-150mhz (model a). I tried to retune the coils for receiveing on 2 meter but they just would not make it. Fortunately, the schematics show what parts differ from each version made! Basically I had to INCREASE the value of certain capacitors in the circuit to turn the unit into a model A. The great part about that is that capacitors in parallel add so I was able to just turn the unit over and just solder 1pf to 5pf capacitors where needed on the back of the circuit board in parallel with the current caps without having to desolder a single component. That made it very easy!! Once that was done, I followed the service manual's instructions for retuning the unit up completely from receiver to xmiter. I can get a full 40 watts out if I push it but I set it down to 25 because I wanted to have longer qso's without heating up the finals too much. If you want a photo of the back of my unit to show you where the caps I added went I can possibly do that as well.  Here is a list of the capacitors I modified by soldering ceramic
disc caps on the back of the circuit board in parallel. You don't need to match exactly just get close and
you'll be ok.
C208 from 6.8pf to 22pf
c210 from 8.2pf to 22pf
c303 from 82pf to 150pf
c414 from 6.8pf to 8.2pf
c416 from 8.2pf to 10pf
c419 from 5.6pf to 6.8pf
c421 from 8.2pf to 10pf
c426 from 6.8pf to 8.2pf
c428 from 6.8pf to 8.2pf
c526 from 3.3pf to 4.7pf
c528 from 6.8pf to 10pf
c529 from 3.8pf to 4.7pf
c534 from 6.8pf to 10pf
c537 from 22pf to 27pf

Once completed then tune per the service manual located here:
http://www.repeater-builder.com/relm-regency-wilson/pdfs/rh250-rh256-wh516-svc-manual.pdf

A WORD OF CAUTION: You may have to remove the front control head during tuning of the coils underneath. Try not to disconnect the thin membrane keypad connector. The others are hard wire
and they are fine but the thin membrane connector may get scraped or damaged by removing it
especially if it is old and it will not conduct properly anymore rendering the keypad useless. Trust
me I know!  Embarrassed

Hope this helps, it's a great unit. Next step for me is to figure out how data is clocked into the pll synthesizer chips and I'm going to make a new front end for the unit with a vfd display, tuning knob and other features I wanted rather than just the 10 selected freqs. BTW, the manual explains how to program the frequencies and you will need to program at least 3 144mhz 146mhz (center band) and 148mhz for proper tuning and alignment.
« Last Edit: June 21, 2011, 04:31:58 PM by KF7PSM » Logged
KD0ILS
Member

Posts: 7




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« Reply #2 on: January 10, 2012, 11:03:49 AM »

Did you replace all the capacitors with a 50V rating?  I noticed that C208 and C210 are 500V ratings and those capacitors seem to be hard to find
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KB1GTX
Member

Posts: 460




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« Reply #3 on: March 01, 2012, 09:46:48 PM »

I know this is old,,

But I've used many of these and they'll work quite well just with a proper tuning for the ham band,, They tune to at least .2 uv for 20dbq and will hit 25 watts,, but the draw back to not changing out the parts seems to be a narrowing of performance band width,, so It doesnt cover the whole band but is perfect for about 2mhz and does real well for 3mhz..

On the 606 60watt models the PA doest work at 148 mhz and needs some caps changed.
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